Adding upstream version 5.28.2+dfsg1+~cs23.11.12.3.upstream/5.28.2+dfsg1+_cs23.11.12.3upstream

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

168 files changed, 32627 insertions, 0 deletions

diff --git a/test/wpt/tests/resources/.htaccess b/test/wpt/tests/resources/.htaccess
new file mode 100644
index 0000000..fd46101
--- /dev/null
+++ b/test/wpt/tests/resources/.htaccess
@@ -0,0 +1,2 @@
+# make tests that use utf-16 not inherit the encoding for testharness.js et. al.
+AddCharset utf-8 .css .js
diff --git a/test/wpt/tests/resources/META.yml b/test/wpt/tests/resources/META.yml
new file mode 100644
index 0000000..64a240c
--- /dev/null
+++ b/test/wpt/tests/resources/META.yml
@@ -0,0 +1,2 @@
+suggested_reviewers:
+  - jgraham
diff --git a/test/wpt/tests/resources/SVGAnimationTestCase-testharness.js b/test/wpt/tests/resources/SVGAnimationTestCase-testharness.js
new file mode 100644
index 0000000..9ebaf68
--- /dev/null
+++ b/test/wpt/tests/resources/SVGAnimationTestCase-testharness.js
@@ -0,0 +1,102 @@
+// NOTE(edvardt):
+// This file is a slimmed down wrapper for the old SVGAnimationTestCase.js,
+// it has some convenience functions and should not be used for new tests.
+// New tests should not build on this API as it's just meant to keep things
+// working.
+
+// Helper functions
+const xlinkNS = "http://www.w3.org/1999/xlink"
+
+function expectFillColor(element, red, green, blue, message) {
+    let color = window.getComputedStyle(element, null).fill;
+    var re = new RegExp("rgba?\\(([^, ]*), ([^, ]*), ([^, ]*)(?:, )?([^, ]*)\\)");
+    rgb = re.exec(color);
+
+    assert_approx_equals(Number(rgb[1]), red, 2.0, message);
+    assert_approx_equals(Number(rgb[2]), green, 2.0, message);
+    assert_approx_equals(Number(rgb[3]), blue, 2.0, message);
+}
+
+function expectColor(element, red, green, blue, property) {
+    if (typeof property != "string")
+      color = getComputedStyle(element).getPropertyValue("color");
+    else
+      color = getComputedStyle(element).getPropertyValue(property);
+    var re = new RegExp("rgba?\\(([^, ]*), ([^, ]*), ([^, ]*)(?:, )?([^, ]*)\\)");
+    rgb = re.exec(color);
+    assert_approx_equals(Number(rgb[1]), red, 2.0);
+    assert_approx_equals(Number(rgb[2]), green, 2.0);
+    assert_approx_equals(Number(rgb[3]), blue, 2.0);
+}
+
+function createSVGElement(type) {
+  return document.createElementNS("http://www.w3.org/2000/svg", type);
+}
+
+// Inspired by Layoutests/animations/animation-test-helpers.js
+function moveAnimationTimelineAndSample(index) {
+    var animationId = expectedResults[index][0];
+    var time = expectedResults[index][1];
+    var sampleCallback = expectedResults[index][2];
+    var animation = rootSVGElement.ownerDocument.getElementById(animationId);
+
+    // If we want to sample the animation end, add a small delta, to reliable point past the end of the animation.
+    newTime = time;
+
+    // The sample time is relative to the start time of the animation, take that into account.
+    rootSVGElement.setCurrentTime(newTime);
+
+    // NOTE(edvardt):
+    // This is a dumb hack, some of the old tests sampled before the animation start, this
+    // isn't technically part of the animation tests and is "impossible" to translate since
+    // tests start automatically. Thus I solved it by skipping it.
+    if (time != 0.0)
+        sampleCallback();
+}
+
+var currentTest = 0;
+var expectedResults;
+
+function sampleAnimation(t) {
+    if (currentTest == expectedResults.length) {
+        t.done();
+        return;
+    }
+
+    moveAnimationTimelineAndSample(currentTest);
+    ++currentTest;
+
+    step_timeout(t.step_func(function () { sampleAnimation(t); }), 0);
+}
+
+function runAnimationTest(t, expected) {
+    if (!expected)
+        throw("Expected results are missing!");
+    if (currentTest > 0)
+        throw("Not allowed to call runAnimationTest() twice");
+
+    expectedResults = expected;
+    testCount = expectedResults.length;
+    currentTest = 0;
+
+    step_timeout(t.step_func(function () { sampleAnimation(this); }), 50);
+}
+
+function smil_async_test(func) {
+  async_test(t => {
+    window.onload = t.step_func(function () {
+      // Pause animations, we'll drive them manually.
+      // This also ensures that the timeline is paused before
+      // it starts. This should make the instance time of the below
+      // 'click' (for instance) 0, and hence minimize rounding
+      // errors for the addition in moveAnimationTimelineAndSample.
+      rootSVGElement.pauseAnimations();
+
+      // If eg. an animation is running with begin="0s", and
+      // we want to sample the first time, before the animation
+      // starts, then we can't delay the testing by using an
+      // onclick event, as the animation would be past start time.
+      func(t);
+    });
+  });
+}
diff --git a/test/wpt/tests/resources/accesskey.js b/test/wpt/tests/resources/accesskey.js
new file mode 100644
index 0000000..e95c9d2
--- /dev/null
+++ b/test/wpt/tests/resources/accesskey.js
@@ -0,0 +1,34 @@
+/*
+ * Function that sends an accesskey using the proper key combination depending on the browser and OS.
+ *
+ * This needs that the test imports the following scripts:
+ *     <script src="/resources/testdriver.js"></script>
+ *     <script src="/resources/testdriver-actions.js"></script>
+ *     <script src="/resources/testdriver-vendor.js"></script>
+*/
+function pressAccessKey(accessKey){
+  let controlKey = '\uE009'; // left Control key
+  let altKey = '\uE00A'; // left Alt key
+  let optionKey = altKey;  // left Option key
+  let shiftKey = '\uE008'; // left Shift key
+  // There are differences in using accesskey across browsers and OS's.
+  // See: // https://developer.mozilla.org/en-US/docs/Web/HTML/Global_attributes/accesskey
+  let isMacOSX = navigator.userAgent.indexOf("Mac") != -1;
+  let osAccessKey = isMacOSX ? [controlKey, optionKey] : [shiftKey, altKey];
+  let actions = new test_driver.Actions();
+  // Press keys.
+  for (let key of osAccessKey) {
+    actions = actions.keyDown(key);
+  }
+  actions = actions
+            .keyDown(accessKey)
+            .addTick()
+            .keyUp(accessKey);
+  osAccessKey.reverse();
+  for (let key of osAccessKey) {
+    actions = actions.keyUp(key);
+  }
+  return actions.send();
+}
+
+
diff --git a/test/wpt/tests/resources/blank.html b/test/wpt/tests/resources/blank.html
new file mode 100644
index 0000000..edeaa45
--- /dev/null
+++ b/test/wpt/tests/resources/blank.html
@@ -0,0 +1,16 @@
+<!DOCTYPE html>
+<html>
+  <head>
+    <meta charset="utf-8" />
+    <title>Blank Page</title>
+    <script>
+      window.onload = function(event) {
+        // This is needed to ensure the onload event fires when this page is
+        // opened as a popup.
+        // See https://github.com/web-platform-tests/wpt/pull/18157
+      };
+    </script>
+  </head>
+  <body>
+  </body>
+</html>
diff --git a/test/wpt/tests/resources/channel.sub.js b/test/wpt/tests/resources/channel.sub.js
new file mode 100644
index 0000000..370d4f5
--- /dev/null
+++ b/test/wpt/tests/resources/channel.sub.js
@@ -0,0 +1,1097 @@
+(function() {
+    function randInt(bits) {
+        if (bits < 1 || bits > 53) {
+            throw new TypeError();
+        } else {
+            if (bits >= 1 && bits <= 30) {
+                return 0 | ((1 << bits) * Math.random());
+            } else {
+                var high = (0 | ((1 << (bits - 30)) * Math.random())) * (1 << 30);
+                var low = 0 | ((1 << 30) * Math.random());
+                return  high + low;
+            }
+        }
+    }
+
+
+    function toHex(x, length) {
+        var rv = x.toString(16);
+        while (rv.length < length) {
+            rv = "0" + rv;
+        }
+        return rv;
+    }
+
+    function createUuid() {
+        return [toHex(randInt(32), 8),
+         toHex(randInt(16), 4),
+         toHex(0x4000 | randInt(12), 4),
+         toHex(0x8000 | randInt(14), 4),
+         toHex(randInt(48), 12)].join("-");
+    }
+
+
+    /**
+     * Cache of WebSocket instances per channel
+     *
+     * For reading there can only be one channel with each UUID, so we
+     * just have a simple map of {uuid: WebSocket}. The socket can be
+     * closed when the channel is closed.
+     *
+     * For writing there can be many channels for each uuid. Those can
+     * share a websocket (within a specific global), so we have a map
+     * of {uuid: [WebSocket, count]}.  Count is incremented when a
+     * channel is opened with a given uuid, and decremented when its
+     * closed. When the count reaches zero we can close the underlying
+     * socket.
+     */
+    class SocketCache {
+        constructor() {
+            this.readSockets = new Map();
+            this.writeSockets = new Map();
+        };
+
+        async getOrCreate(type, uuid, onmessage=null) {
+            function createSocket() {
+                let protocol = self.isSecureContext ? "wss" : "ws";
+                let port = self.isSecureContext? "{{ports[wss][0]}}" : "{{ports[ws][0]}}";
+                let url = `${protocol}://{{host}}:${port}/msg_channel?uuid=${uuid}&direction=${type}`;
+                let socket = new WebSocket(url);
+                if (onmessage !== null) {
+                    socket.onmessage = onmessage;
+                };
+                return new Promise(resolve => socket.addEventListener("open", () => resolve(socket)));
+            }
+
+            let socket;
+            if (type === "read") {
+                if (this.readSockets.has(uuid)) {
+                    throw new Error("Can't create multiple read sockets with same UUID");
+                }
+                socket = await createSocket();
+                // If the socket is closed by the server, ensure it's removed from the cache
+                socket.addEventListener("close", () => this.readSockets.delete(uuid));
+                this.readSockets.set(uuid, socket);
+            } else if (type === "write") {
+                let count;
+                if (onmessage !== null) {
+                    throw new Error("Can't set message handler for write sockets");
+                }
+                if (this.writeSockets.has(uuid)) {
+                    [socket, count] = this.writeSockets.get(uuid);
+                } else {
+                    socket = await createSocket();
+                    count = 0;
+                }
+                count += 1;
+                // If the socket is closed by the server, ensure it's removed from the cache
+                socket.addEventListener("close", () => this.writeSockets.delete(uuid));
+                this.writeSockets.set(uuid, [socket, count]);
+            } else {
+                throw new Error(`Unknown type ${type}`);
+            }
+            return socket;
+        };
+
+        async close(type, uuid) {
+            let target = type === "read" ? this.readSockets : this.writeSockets;
+            const data = target.get(uuid);
+            if (!data) {
+                return;
+            }
+            let count, socket;
+            if (type == "read") {
+                socket = data;
+                count = 0;
+            } else if (type === "write") {
+                [socket, count] = data;
+                count -= 1;
+                if (count > 0) {
+                    target.set(uuid, [socket, count]);
+                }
+            };
+            if (count <= 0 && socket) {
+                target.delete(uuid);
+                socket.close(1000);
+                await new Promise(resolve => socket.addEventListener("close", resolve));
+            }
+        };
+
+        async closeAll() {
+            let sockets = [];
+            this.readSockets.forEach(value => sockets.push(value));
+            this.writeSockets.forEach(value => sockets.push(value[0]));
+            let closePromises = sockets.map(socket =>
+                new Promise(resolve => socket.addEventListener("close", resolve)));
+            sockets.forEach(socket => socket.close(1000));
+            this.readSockets.clear();
+            this.writeSockets.clear();
+            await Promise.all(closePromises);
+        }
+    }
+
+    const socketCache = new SocketCache();
+
+    /**
+     * Abstract base class for objects that allow sending / receiving
+     * messages over a channel.
+     */
+    class Channel {
+        type = null;
+
+        constructor(uuid) {
+            /** UUID for the channel */
+            this.uuid = uuid;
+            this.socket = null;
+            this.eventListeners = {
+                connect: new Set(),
+                close: new Set()
+            };
+        }
+
+        hasConnection() {
+            return this.socket !== null && this.socket.readyState <= WebSocket.OPEN;
+        }
+
+        /**
+         * Connect to the channel.
+         *
+         * @param {Function} onmessage - Event handler function for
+         * the underlying websocket message.
+         */
+        async connect(onmessage) {
+            if (this.hasConnection()) {
+                return;
+            }
+            this.socket = await socketCache.getOrCreate(this.type, this.uuid, onmessage);
+            this._dispatch("connect");
+        }
+
+        /**
+         * Close the channel and underlying websocket connection
+         */
+        async close() {
+            this.socket = null;
+            await socketCache.close(this.type, this.uuid);
+            this._dispatch("close");
+        }
+
+        /**
+         * Add an event callback function. Supported message types are
+         * "connect", "close", and "message" (for ``RecvChannel``).
+         *
+         * @param {string} type - Message type.
+         * @param {Function} fn - Callback function. This is called
+         * with an event-like object, with ``type`` and ``data``
+         * properties.
+         */
+        addEventListener(type, fn) {
+            if (typeof type !== "string") {
+                throw new TypeError(`Expected string, got ${typeof type}`);
+            }
+            if (typeof fn !== "function") {
+                throw new TypeError(`Expected function, got ${typeof fn}`);
+            }
+            if (!this.eventListeners.hasOwnProperty(type)) {
+                throw new Error(`Unrecognised event type ${type}`);
+            }
+            this.eventListeners[type].add(fn);
+        };
+
+        /**
+         * Remove an event callback function.
+         *
+         * @param {string} type - Event type.
+         * @param {Function} fn - Callback function to remove.
+         */
+        removeEventListener(type, fn) {
+            if (!typeof type === "string") {
+                throw new TypeError(`Expected string, got ${typeof type}`);
+            }
+            if (typeof fn !== "function") {
+                throw new TypeError(`Expected function, got ${typeof fn}`);
+            }
+            let listeners = this.eventListeners[type];
+            if (listeners) {
+                listeners.delete(fn);
+            }
+        };
+
+        _dispatch(type, data) {
+            let listeners = this.eventListeners[type];
+            if (listeners) {
+                // If any listener throws we end up not calling the other
+                // listeners. This hopefully makes debugging easier, but
+                // is different to DOM event listeners.
+                listeners.forEach(fn => fn({type, data}));
+            }
+        };
+
+    }
+
+    /**
+     * Send messages over a channel
+     */
+    class SendChannel extends Channel {
+        type = "write";
+
+        /**
+         * Connect to the channel. Automatically called when sending the
+         * first message.
+         */
+        async connect() {
+            return super.connect(null);
+        }
+
+        async _send(cmd, body=null) {
+            if (!this.hasConnection()) {
+                await this.connect();
+            }
+            this.socket.send(JSON.stringify([cmd, body]));
+        }
+
+        /**
+         * Send a message. The message object must be JSON-serializable.
+         *
+         * @param {Object} msg - The message object to send.
+         */
+        async send(msg) {
+            await this._send("message", msg);
+        }
+
+        /**
+         * Disconnect the associated `RecvChannel <#RecvChannel>`_, if
+         * any, on the server side.
+         */
+        async disconnectReader() {
+            await this._send("disconnectReader");
+        }
+
+        /**
+         * Disconnect this channel on the server side.
+         */
+        async delete() {
+            await this._send("delete");
+        }
+    };
+    self.SendChannel = SendChannel;
+
+    const recvChannelsCreated = new Set();
+
+    /**
+     * Receive messages over a channel
+     */
+    class RecvChannel extends Channel {
+        type = "read";
+
+        constructor(uuid) {
+            if (recvChannelsCreated.has(uuid)) {
+                throw new Error(`Already created RecvChannel with id ${uuid}`);
+            }
+            super(uuid);
+            this.eventListeners.message = new Set();
+        }
+
+        async connect() {
+            if (this.hasConnection()) {
+                return;
+            }
+            await super.connect(event => this.readMessage(event.data));
+        }
+
+        readMessage(data) {
+            let msg = JSON.parse(data);
+            this._dispatch("message", msg);
+        }
+
+        /**
+         * Wait for the next message and return it (after passing it to
+         * existing handlers)
+         *
+         * @returns {Promise} - Promise that resolves to the message data.
+         */
+        nextMessage() {
+            return new Promise(resolve => {
+                let fn = ({data}) => {
+                    this.removeEventListener("message", fn);
+                    resolve(data);
+                };
+                this.addEventListener("message", fn);
+            });
+        }
+    }
+
+    /**
+     * Create a new channel pair
+     *
+     * @returns {Array} - Array of [RecvChannel, SendChannel] for the same channel.
+     */
+    self.channel = function() {
+        let uuid = createUuid();
+        let recvChannel = new RecvChannel(uuid);
+        let sendChannel = new SendChannel(uuid);
+        return [recvChannel, sendChannel];
+    };
+
+    /**
+     * Create an unconnected channel defined by a `uuid` in
+     * ``location.href`` for listening for `RemoteGlobal
+     * <#RemoteGlobal>`_ messages.
+     *
+     * @returns {RemoteGlobalCommandRecvChannel} - Disconnected channel
+     */
+    self.global_channel = function() {
+        let uuid = new URLSearchParams(location.search).get("uuid");
+        if (!uuid) {
+            throw new Error("URL must have a uuid parameter to use as a RemoteGlobal");
+        }
+        return new RemoteGlobalCommandRecvChannel(new RecvChannel(uuid));
+    };
+
+    /**
+     * Start listening for `RemoteGlobal <#RemoteGlobal>`_ messages on
+     * a channel defined by a `uuid` in `location.href`
+     *
+     * @returns {RemoteGlobalCommandRecvChannel} - Connected channel
+     */
+    self.start_global_channel = async function() {
+        let channel = self.global_channel();
+        await channel.connect();
+        return channel;
+    };
+
+    /**
+     * Close all WebSockets used by channels in the current realm.
+     *
+     */
+    self.close_all_channel_sockets = async function() {
+        await socketCache.closeAll();
+        // Spinning the event loop after the close events is necessary to
+        // ensure that the channels really are closed and don't affect
+        // bfcache behaviour in at least some implementations.
+        await new Promise(resolve => setTimeout(resolve, 0));
+    };
+
+    /**
+     * Handler for `RemoteGlobal <#RemoteGlobal>`_ commands.
+     *
+     * This can't be constructed directly but must be obtained from
+     * `global_channel() <#global_channel>`_ or
+     * `start_global_channel() <#start_global_channel>`_.
+     */
+    class RemoteGlobalCommandRecvChannel {
+        constructor(recvChannel) {
+            this.channel = recvChannel;
+            this.uuid = recvChannel.uuid;
+            this.channel.addEventListener("message", ({data}) => this.handleMessage(data));
+            this.messageHandlers = new Set();
+        };
+
+        /**
+         * Connect to the channel and start handling messages.
+         */
+        async connect() {
+            await this.channel.connect();
+        }
+
+        /**
+         * Close the channel and underlying websocket connection
+         */
+        async close() {
+            await this.channel.close();
+        }
+
+        async handleMessage(msg) {
+            const {id, command, params, respChannel} = msg;
+            let result = {};
+            let resp = {id, result};
+            if (command === "call") {
+                const fn = deserialize(params.fn);
+                const args = params.args.map(deserialize);
+                try {
+                    let resultValue = await fn(...args);
+                    result.result = serialize(resultValue);
+                } catch(e) {
+                    let exception = serialize(e);
+                    const getAsInt = (obj, prop) =>  {
+                        let value = prop in obj ? parseInt(obj[prop]) : 0;
+                        return Number.isNaN(value) ? 0 : value;
+                    };
+                    result.exceptionDetails = {
+                        text: e.toString(),
+                        lineNumber: getAsInt(e, "lineNumber"),
+                        columnNumber: getAsInt(e, "columnNumber"),
+                        exception
+                    };
+                }
+            } else if (command === "postMessage") {
+                this.messageHandlers.forEach(fn => fn(deserialize(params.msg)));
+            }
+            if (respChannel) {
+                let chan = deserialize(respChannel);
+                await chan.connect();
+                await chan.send(resp);
+            }
+        }
+
+        /**
+         * Add a handler for ``postMessage`` messages
+         *
+         * @param {Function} fn - Callback function that receives the
+         * message.
+         */
+        addMessageHandler(fn) {
+            this.messageHandlers.add(fn);
+        }
+
+        /**
+         * Remove a handler for ``postMessage`` messages
+         *
+         * @param {Function} fn - Callback function to remove
+         */
+        removeMessageHandler(fn) {
+            this.messageHandlers.delete(fn);
+        }
+
+        /**
+         * Wait for the next ``postMessage`` message and return it
+         * (after passing it to existing handlers)
+         *
+         * @returns {Promise} - Promise that resolves to the message.
+         */
+        nextMessage() {
+            return new Promise(resolve => {
+                let fn = (msg) => {
+                    this.removeMessageHandler(fn);
+                    resolve(msg);
+                };
+                this.addMessageHandler(fn);
+            });
+        }
+    }
+
+    class RemoteGlobalResponseRecvChannel {
+        constructor(recvChannel) {
+            this.channel = recvChannel;
+            this.channel.addEventListener("message", ({data}) => this.handleMessage(data));
+            this.responseHandlers = new Map();
+        }
+
+        setResponseHandler(commandId, fn) {
+            this.responseHandlers.set(commandId, fn);
+        }
+
+        handleMessage(msg) {
+            let {id, result} = msg;
+            let handler = this.responseHandlers.get(id);
+            if (handler) {
+                this.responseHandlers.delete(id);
+                handler(result);
+            }
+        }
+
+        close() {
+            return this.channel.close();
+        }
+    }
+
+    /**
+     * Object representing a remote global that has a
+     * `RemoteGlobalCommandRecvChannel
+     * <#RemoteGlobalCommandRecvChannel>`_
+     */
+    class RemoteGlobal {
+        /**
+         * Create a new RemoteGlobal object.
+         *
+         * This doesn't actually construct the global itself; that
+         * must be done elsewhere, with a ``uuid`` query parameter in
+         * its URL set to the same as the ``uuid`` property of this
+         * object.
+         *
+         * @param {SendChannel|string} [dest] - Either a SendChannel
+         * to the destination, or the UUID of the destination. If
+         * ommitted, a new UUID is generated, which can be used when
+         * constructing the URL for the global.
+         *
+         */
+        constructor(dest) {
+            if (dest === undefined || dest === null) {
+                dest = createUuid();
+            }
+            if (typeof dest == "string") {
+                /** UUID for the global */
+                this.uuid = dest;
+                this.sendChannel = new SendChannel(dest);
+            } else if (dest instanceof SendChannel) {
+                this.sendChannel = dest;
+                this.uuid = dest.uuid;
+            } else {
+                throw new TypeError("Unrecognised type, expected string or SendChannel");
+            }
+            this.recvChannel = null;
+            this.respChannel = null;
+            this.connected = false;
+            this.commandId = 0;
+        }
+
+        /**
+         * Connect to the channel. Automatically called when sending the
+         * first message
+         */
+        async connect() {
+            if (this.connected) {
+                return;
+            }
+            let [recvChannel, respChannel] = self.channel();
+            await Promise.all([this.sendChannel.connect(), recvChannel.connect()]);
+            this.recvChannel = new RemoteGlobalResponseRecvChannel(recvChannel);
+            this.respChannel = respChannel;
+            this.connected = true;
+        }
+
+        async sendMessage(command, params, hasResp=true) {
+            if (!this.connected) {
+                await this.connect();
+            }
+            let msg = {id: this.commandId++, command, params};
+            if (hasResp) {
+                msg.respChannel = serialize(this.respChannel);
+            }
+            let response;
+            if (hasResp) {
+                response = new Promise(resolve =>
+                    this.recvChannel.setResponseHandler(msg.id, resolve));
+            } else {
+                response = null;
+            }
+            this.sendChannel.send(msg);
+            return await response;
+        }
+
+        /**
+         * Run the function ``fn`` in the remote global, passing arguments
+         * ``args``, and return the result after awaiting any returned
+         * promise.
+         *
+         * @param {Function} fn - Function to run in the remote global.
+         * @param {...Any} args  - Arguments to pass to the function
+         * @returns {Promise} - Promise resolving to the return value
+         * of the function.
+         */
+        async call(fn, ...args) {
+            let result = await this.sendMessage("call", {fn: serialize(fn), args: args.map(x => serialize(x))}, true);
+            if (result.exceptionDetails) {
+                throw deserialize(result.exceptionDetails.exception);
+            }
+            return deserialize(result.result);
+        }
+
+        /**
+         * Post a message to the remote
+         *
+         * @param {Any} msg - The message to send.
+         */
+        async postMessage(msg) {
+            await this.sendMessage("postMessage", {msg: serialize(msg)}, false);
+        }
+
+        /**
+         * Disconnect the associated `RemoteGlobalCommandRecvChannel
+         * <#RemoteGlobalCommandRecvChannel>`_, if any, on the server
+         * side.
+         *
+         * @returns {Promise} - Resolved once the channel is disconnected.
+         */
+        disconnectReader() {
+            // This causes any readers to disconnect until they are explicitly reconnected
+            return this.sendChannel.disconnectReader();
+        }
+
+        /**
+         * Close the channel and underlying websocket connections
+         */
+        close() {
+            let closers = [this.sendChannel.close()];
+            if (this.recvChannel !== null) {
+                closers.push(this.recvChannel.close());
+            }
+            if (this.respChannel !== null) {
+                closers.push(this.respChannel.close());
+            }
+            return Promise.all(closers);
+        }
+    }
+
+    self.RemoteGlobal = RemoteGlobal;
+
+    function typeName(value) {
+        let type = typeof value;
+        if (type === "undefined" ||
+            type === "string" ||
+            type === "boolean" ||
+            type === "number" ||
+            type === "bigint" ||
+            type === "symbol" ||
+            type === "function") {
+            return type;
+        }
+
+        if (value === null) {
+            return "null";
+        }
+        // The handling of cross-global objects here is broken
+        if (value instanceof RemoteObject) {
+            return "remoteobject";
+        }
+        if (value instanceof SendChannel) {
+            return "sendchannel";
+        }
+        if (value instanceof RecvChannel) {
+            return "recvchannel";
+        }
+        if (value instanceof Error) {
+            return "error";
+        }
+        if (Array.isArray(value)) {
+            return "array";
+        }
+        let constructor = value.constructor && value.constructor.name;
+        if (constructor === "RegExp" ||
+            constructor === "Date" ||
+            constructor === "Map" ||
+            constructor === "Set" ||
+            constructor == "WeakMap" ||
+            constructor == "WeakSet") {
+            return constructor.toLowerCase();
+        }
+        // The handling of cross-global objects here is broken
+        if (typeof window == "object" && window === self) {
+            if (value instanceof Element) {
+                return "element";
+            }
+            if (value instanceof Document) {
+                return "document";
+            }
+            if (value instanceof Node) {
+                return "node";
+            }
+            if (value instanceof Window) {
+                return "window";
+            }
+        }
+        if (Promise.resolve(value) === value) {
+            return "promise";
+        }
+        return "object";
+    }
+
+    let remoteObjectsById = new Map();
+
+    function remoteId(obj) {
+        let rv;
+        rv = createUuid();
+        remoteObjectsById.set(rv, obj);
+        return rv;
+    }
+
+    /**
+     * Representation of a non-primitive type passed through a channel
+     */
+    class RemoteObject {
+        constructor(type, objectId) {
+            this.type = type;
+            this.objectId = objectId;
+        }
+
+        /**
+         * Create a RemoteObject containing a handle to reference obj
+         *
+         * @param {Any} obj - The object to reference.
+         */
+        static from(obj) {
+            let type = typeName(obj);
+            let id = remoteId(obj);
+            return new RemoteObject(type, id);
+        }
+
+        /**
+         * Return the local object referenced by the ``objectId`` of
+         * this ``RemoteObject``, or ``null`` if there isn't a such an
+         * object in this realm.
+         */
+        toLocal() {
+            if (remoteObjectsById.has(this.objectId)) {
+                return remoteObjectsById.get(this.objectId);
+            }
+            return null;
+        }
+
+        /**
+         * Remove the object from the local cache. This means that future
+         * calls to ``toLocal`` with the same objectId will always return
+         * ``null``.
+         */
+        delete() {
+            remoteObjectsById.delete(this.objectId);
+        }
+    }
+
+    self.RemoteObject = RemoteObject;
+
+    /**
+     * Serialize an object as a JSON-compatible representation.
+     *
+     * The format used is similar (but not identical to)
+     * `WebDriver-BiDi
+     * <https://w3c.github.io/webdriver-bidi/#data-types-protocolValue>`_.
+     *
+     * Each item to be serialized can have the following fields:
+     *
+     * type - The name of the type being represented e.g. "string", or
+     *  "map". For primitives this matches ``typeof``, but for
+     *  ``object`` types that have particular support in the protocol
+     *  e.g. arrays and maps, it is a custom value.
+     *
+     * value - A serialized representation of the object value. For
+     * container types this is a JSON container (i.e. an object or an
+     * array) containing a serialized representation of the child
+     * values.
+     *
+     * objectId - An integer used to handle object graphs. Where
+     * an object is present more than once in the serialization, the
+     * first instance has both ``value`` and ``objectId`` fields, but
+     * when encountered again, only ``objectId`` is present, with the
+     * same value as the first instance of the object.
+     *
+     * @param {Any} inValue - The value to be serialized.
+     * @returns {Object} - The serialized object value.
+     */
+    function serialize(inValue) {
+        const queue = [{item: inValue}];
+        let outValue = null;
+
+        // Map from container object input to output value
+        let objectsSeen = new Map();
+        let lastObjectId = 0;
+
+        /* Instead of making this recursive, use a queue holding the objects to be
+         * serialized. Each item in the queue can have the following properties:
+         *
+         * item (required) - the input item to be serialized
+         *
+         * target - For collections, the output serialized object to
+         * which the serialization of the current item will be added.
+         *
+         * targetName - For serializing object members, the name of
+         * the property. For serializing maps either "key" or "value",
+         * depending on whether the item represents a key or a value
+         * in the map.
+         */
+        while (queue.length > 0) {
+            const {item, target, targetName} = queue.shift();
+            let type = typeName(item);
+
+            let serialized = {type};
+
+            if (objectsSeen.has(item)) {
+                let outputValue = objectsSeen.get(item);
+                if (!outputValue.hasOwnProperty("objectId")) {
+                    outputValue.objectId = lastObjectId++;
+                }
+                serialized.objectId = outputValue.objectId;
+            } else {
+                switch (type) {
+                case "undefined":
+                case "null":
+                    break;
+                case "string":
+                case "boolean":
+                    serialized.value = item;
+                    break;
+                case "number":
+                    if (item !== item) {
+                        serialized.value = "NaN";
+                    } else if (item === 0 && 1/item == Number.NEGATIVE_INFINITY) {
+                        serialized.value = "-0";
+                    } else if (item === Number.POSITIVE_INFINITY) {
+                        serialized.value = "+Infinity";
+                    } else if (item === Number.NEGATIVE_INFINITY) {
+                        serialized.value = "-Infinity";
+                    } else {
+                        serialized.value = item;
+                    }
+                    break;
+                case "bigint":
+                case "function":
+                    serialized.value = item.toString();
+                    break;
+                case "remoteobject":
+                    serialized.value = {
+                        type: item.type,
+                        objectId: item.objectId
+                    };
+                    break;
+                case "sendchannel":
+                    serialized.value = item.uuid;
+                    break;
+                case "regexp":
+                    serialized.value = {
+                        pattern: item.source,
+                        flags: item.flags
+                    };
+                    break;
+                case "date":
+                    serialized.value = Date.prototype.toJSON.call(item);
+                    break;
+                case "error":
+                    serialized.value = {
+                        type: item.constructor.name,
+                        name: item.name,
+                        message: item.message,
+                        lineNumber: item.lineNumber,
+                        columnNumber: item.columnNumber,
+                        fileName: item.fileName,
+                        stack: item.stack,
+                    };
+                    break;
+                case "array":
+                case "set":
+                    serialized.value = [];
+                    for (let child of item) {
+                        queue.push({item: child, target: serialized});
+                    }
+                    break;
+                case "object":
+                    serialized.value = {};
+                    for (let [targetName, child] of Object.entries(item)) {
+                        queue.push({item: child, target: serialized, targetName});
+                    }
+                    break;
+                case "map":
+                    serialized.value = [];
+                    for (let [childKey, childValue] of item.entries()) {
+                        queue.push({item: childKey, target: serialized, targetName: "key"});
+                        queue.push({item: childValue, target: serialized, targetName: "value"});
+                    }
+                    break;
+                default:
+                    throw new TypeError(`Can't serialize value of type ${type}; consider using RemoteObject.from() to wrap the object`);
+                };
+            }
+            if (serialized.objectId === undefined) {
+                objectsSeen.set(item, serialized);
+            }
+
+            if (target === undefined) {
+                if (outValue !== null) {
+                    throw new Error("Tried to create multiple output values");
+                }
+                outValue = serialized;
+            } else {
+                switch (target.type) {
+                case "array":
+                case "set":
+                    target.value.push(serialized);
+                    break;
+                case "object":
+                    target.value[targetName] = serialized;
+                    break;
+                case "map":
+                    // We always serialize key and value as adjacent items in the queue,
+                    // so when we get the key push a new output array and then the value will
+                    // be added on the next iteration.
+                    if (targetName === "key") {
+                        target.value.push([]);
+                    }
+                    target.value[target.value.length - 1].push(serialized);
+                    break;
+                default:
+                    throw new Error(`Unknown collection target type ${target.type}`);
+                }
+            }
+        }
+        return outValue;
+    }
+
+    /**
+     * Deserialize an object from a JSON-compatible representation.
+     *
+     * For details on the serialized representation see serialize().
+     *
+     * @param {Object} obj - The value to be deserialized.
+     * @returns {Any} - The deserialized value.
+     */
+    function deserialize(obj) {
+        let deserialized = null;
+        let queue = [{item: obj, target: null}];
+        let objectMap = new Map();
+
+        /* Instead of making this recursive, use a queue holding the objects to be
+         * deserialized. Each item in the queue has the following properties:
+         *
+         * item - The input item to be deserialised.
+         *
+         * target - For members of a collection, a wrapper around the
+         * output collection. This has a ``type`` field which is the
+         * name of the collection type, and a ``value`` field which is
+         * the actual output collection. For primitives, this is null.
+         *
+         * targetName - For object members, the property name on the
+         * output object. For maps, "key" if the item is a key in the output map,
+         * or "value" if it's a value in the output map.
+         */
+        while (queue.length > 0) {
+            const {item, target, targetName} = queue.shift();
+            const {type, value, objectId} = item;
+            let result;
+            let newTarget;
+            if (objectId !== undefined && value === undefined) {
+                result = objectMap.get(objectId);
+            } else {
+                switch(type) {
+                case "undefined":
+                    result = undefined;
+                    break;
+                case "null":
+                    result = null;
+                    break;
+                case "string":
+                case "boolean":
+                    result = value;
+                    break;
+                case "number":
+                    if (typeof value === "string") {
+                        switch(value) {
+                        case "NaN":
+                            result = NaN;
+                            break;
+                        case "-0":
+                            result = -0;
+                            break;
+                        case "+Infinity":
+                            result = Number.POSITIVE_INFINITY;
+                            break;
+                        case "-Infinity":
+                            result = Number.NEGATIVE_INFINITY;
+                            break;
+                        default:
+                            throw new Error(`Unexpected number value "${value}"`);
+                        }
+                    } else {
+                        result = value;
+                    }
+                    break;
+                case "bigint":
+                    result = BigInt(value);
+                    break;
+                case "function":
+                    result = new Function("...args", `return (${value}).apply(null, args)`);
+                    break;
+                case "remoteobject":
+                    let remote = new RemoteObject(value.type, value.objectId);
+                    let local = remote.toLocal();
+                    if (local !== null) {
+                        result = local;
+                    } else {
+                        result = remote;
+                    }
+                    break;
+                case "sendchannel":
+                    result = new SendChannel(value);
+                    break;
+                case "regexp":
+                    result = new RegExp(value.pattern, value.flags);
+                    break;
+                case "date":
+                    result = new Date(value);
+                    break;
+                case "error":
+                    // The item.value.type property is the name of the error constructor.
+                    // If we have a constructor with the same name in the current realm,
+                    // construct an instance of that type, otherwise use a generic Error
+                    // type.
+                    if (item.value.type in self &&
+                        typeof self[item.value.type] === "function") {
+                        result = new self[item.value.type](item.value.message);
+                    } else {
+                        result = new Error(item.value.message);
+                    }
+                    result.name = item.value.name;
+                    result.lineNumber = item.value.lineNumber;
+                    result.columnNumber = item.value.columnNumber;
+                    result.fileName = item.value.fileName;
+                    result.stack = item.value.stack;
+                    break;
+                case "array":
+                    result = [];
+                    newTarget = {type, value: result};
+                    for (let child of value) {
+                        queue.push({item: child, target: newTarget});
+                    }
+                    break;
+                case "set":
+                    result = new Set();
+                    newTarget = {type, value: result};
+                    for (let child of value) {
+                        queue.push({item: child, target: newTarget});
+                    }
+                    break;
+                case "object":
+                    result = {};
+                    newTarget = {type, value: result};
+                    for (let [targetName, child] of Object.entries(value)) {
+                        queue.push({item: child, target: newTarget, targetName});
+                    }
+                    break;
+                case "map":
+                    result = new Map();
+                    newTarget = {type, value: result};
+                    for (let [key, child] of value) {
+                        queue.push({item: key, target: newTarget, targetName: "key"});
+                        queue.push({item: child, target: newTarget, targetName: "value"});
+                    }
+                    break;
+                default:
+                    throw new TypeError(`Can't deserialize object of type ${type}`);
+                }
+                if (objectId !== undefined) {
+                    objectMap.set(objectId, result);
+                }
+            }
+
+            if (target === null) {
+                if (deserialized !== null) {
+                    throw new Error(`Tried to deserialized a non-root output value without a target`
+                                    ` container object.`);
+                }
+                deserialized = result;
+            } else {
+                switch(target.type) {
+                case "array":
+                    target.value.push(result);
+                    break;
+                case "set":
+                    target.value.add(result);
+                    break;
+                case "object":
+                    target.value[targetName] = result;
+                    break;
+                case "map":
+                    // For maps the same target wrapper is shared between key and value.
+                    // After deserializing the key, set the `key` property on the target
+                    // until we come to the value.
+                    if (targetName === "key") {
+                        target.key = result;
+                    } else {
+                        target.value.set(target.key, result);
+                    }
+                    break;
+                default:
+                    throw new Error(`Unknown target type ${target.type}`);
+                }
+            }
+        }
+        return deserialized;
+    }
+})();
diff --git a/test/wpt/tests/resources/check-layout-th.js b/test/wpt/tests/resources/check-layout-th.js
new file mode 100644
index 0000000..f14ca32
--- /dev/null
+++ b/test/wpt/tests/resources/check-layout-th.js
@@ -0,0 +1,252 @@
+(function() {
+// Test is initiated from body.onload, so explicit done() call is required.
+setup({ explicit_done: true });
+
+function checkSubtreeExpectedValues(t, parent, prefix)
+{
+    var checkedLayout = checkExpectedValues(t, parent, prefix);
+    Array.prototype.forEach.call(parent.childNodes, function(node) {
+        checkedLayout |= checkSubtreeExpectedValues(t, node, prefix);
+    });
+    return checkedLayout;
+}
+
+function checkAttribute(output, node, attribute)
+{
+    var result = node.getAttribute && node.getAttribute(attribute);
+    output.checked |= !!result;
+    return result;
+}
+
+function assert_tolerance(actual, expected, message)
+{
+    if (isNaN(expected) || isNaN(actual) || Math.abs(actual - expected) >= 1) {
+        assert_equals(actual, Number(expected), message);
+    }
+}
+
+function checkDataKeys(node) {
+  // The purpose of this list of data-* attributes is simply to ensure typos
+  // in tests are caught. It is therefore "ok" to add to this list for
+  // specific tests.
+    var validData = new Set([
+        "data-anchor-polyfill",
+        "data-expected-width",
+        "data-expected-height",
+        "data-offset-x",
+        "data-offset-y",
+        "data-expected-client-width",
+        "data-expected-client-height",
+        "data-expected-scroll-width",
+        "data-expected-scroll-height",
+        "data-expected-bounding-client-rect-width",
+        "data-expected-bounding-client-rect-height",
+        "data-total-x",
+        "data-total-y",
+        "data-expected-display",
+        "data-expected-padding-top",
+        "data-expected-padding-bottom",
+        "data-expected-padding-left",
+        "data-expected-padding-right",
+        "data-expected-margin-top",
+        "data-expected-margin-bottom",
+        "data-expected-margin-left",
+        "data-expected-margin-right"
+    ]);
+    if (!node || !node.getAttributeNames)
+        return;
+    // Use "data-test" prefix if you need custom-named data elements.
+    for (let name of node.getAttributeNames()) {
+        if (name.startsWith("data-") && !name.startsWith("data-test"))
+            assert_true(validData.has(name), name + " is a valid data attribute");
+    }
+}
+
+function checkExpectedValues(t, node, prefix)
+{
+    checkDataKeys(node);
+    var output = { checked: false };
+
+    var expectedWidth = checkAttribute(output, node, "data-expected-width");
+    if (expectedWidth) {
+        assert_tolerance(node.offsetWidth, expectedWidth, prefix + "width");
+    }
+
+    var expectedHeight = checkAttribute(output, node, "data-expected-height");
+    if (expectedHeight) {
+        assert_tolerance(node.offsetHeight, expectedHeight, prefix + "height");
+    }
+
+    var expectedOffset = checkAttribute(output, node, "data-offset-x");
+    if (expectedOffset) {
+        assert_tolerance(node.offsetLeft, expectedOffset, prefix + "offsetLeft");
+    }
+
+    var expectedOffset = checkAttribute(output, node, "data-offset-y");
+    if (expectedOffset) {
+        assert_tolerance(node.offsetTop, expectedOffset, prefix + "offsetTop");
+    }
+
+    var expectedWidth = checkAttribute(output, node, "data-expected-client-width");
+    if (expectedWidth) {
+        assert_tolerance(node.clientWidth, expectedWidth, prefix + "clientWidth");
+    }
+
+    var expectedHeight = checkAttribute(output, node, "data-expected-client-height");
+    if (expectedHeight) {
+        assert_tolerance(node.clientHeight, expectedHeight, prefix + "clientHeight");
+    }
+
+    var expectedWidth = checkAttribute(output, node, "data-expected-scroll-width");
+    if (expectedWidth) {
+        assert_tolerance(node.scrollWidth, expectedWidth, prefix + "scrollWidth");
+    }
+
+    var expectedHeight = checkAttribute(output, node, "data-expected-scroll-height");
+    if (expectedHeight) {
+        assert_tolerance(node.scrollHeight, expectedHeight, prefix + "scrollHeight");
+    }
+
+    var expectedWidth = checkAttribute(output, node, "data-expected-bounding-client-rect-width");
+    if (expectedWidth) {
+        assert_tolerance(node.getBoundingClientRect().width, expectedWidth, prefix + "getBoundingClientRect().width");
+    }
+
+    var expectedHeight = checkAttribute(output, node, "data-expected-bounding-client-rect-height");
+    if (expectedHeight) {
+        assert_tolerance(node.getBoundingClientRect().height, expectedHeight, prefix + "getBoundingClientRect().height");
+    }
+
+    var expectedOffset = checkAttribute(output, node, "data-total-x");
+    if (expectedOffset) {
+        var totalLeft = node.clientLeft + node.offsetLeft;
+        assert_tolerance(totalLeft, expectedOffset, prefix +
+                         "clientLeft+offsetLeft (" + node.clientLeft + " + " + node.offsetLeft + ")");
+    }
+
+    var expectedOffset = checkAttribute(output, node, "data-total-y");
+    if (expectedOffset) {
+        var totalTop = node.clientTop + node.offsetTop;
+        assert_tolerance(totalTop, expectedOffset, prefix +
+                         "clientTop+offsetTop (" + node.clientTop + " + " + node.offsetTop + ")");
+    }
+
+    var expectedDisplay = checkAttribute(output, node, "data-expected-display");
+    if (expectedDisplay) {
+        var actualDisplay = getComputedStyle(node).display;
+        assert_equals(actualDisplay, expectedDisplay, prefix + "display");
+    }
+
+    var expectedPaddingTop = checkAttribute(output, node, "data-expected-padding-top");
+    if (expectedPaddingTop) {
+        var actualPaddingTop = getComputedStyle(node).paddingTop;
+        // Trim the unit "px" from the output.
+        actualPaddingTop = actualPaddingTop.slice(0, -2);
+        assert_equals(actualPaddingTop, expectedPaddingTop, prefix + "padding-top");
+    }
+
+    var expectedPaddingBottom = checkAttribute(output, node, "data-expected-padding-bottom");
+    if (expectedPaddingBottom) {
+        var actualPaddingBottom = getComputedStyle(node).paddingBottom;
+        // Trim the unit "px" from the output.
+        actualPaddingBottom = actualPaddingBottom.slice(0, -2);
+        assert_equals(actualPaddingBottom, expectedPaddingBottom, prefix + "padding-bottom");
+    }
+
+    var expectedPaddingLeft = checkAttribute(output, node, "data-expected-padding-left");
+    if (expectedPaddingLeft) {
+        var actualPaddingLeft = getComputedStyle(node).paddingLeft;
+        // Trim the unit "px" from the output.
+        actualPaddingLeft = actualPaddingLeft.slice(0, -2);
+        assert_equals(actualPaddingLeft, expectedPaddingLeft, prefix + "padding-left");
+    }
+
+    var expectedPaddingRight = checkAttribute(output, node, "data-expected-padding-right");
+    if (expectedPaddingRight) {
+        var actualPaddingRight = getComputedStyle(node).paddingRight;
+        // Trim the unit "px" from the output.
+        actualPaddingRight = actualPaddingRight.slice(0, -2);
+        assert_equals(actualPaddingRight, expectedPaddingRight, prefix + "padding-right");
+    }
+
+    var expectedMarginTop = checkAttribute(output, node, "data-expected-margin-top");
+    if (expectedMarginTop) {
+        var actualMarginTop = getComputedStyle(node).marginTop;
+        // Trim the unit "px" from the output.
+        actualMarginTop = actualMarginTop.slice(0, -2);
+        assert_equals(actualMarginTop, expectedMarginTop, prefix + "margin-top");
+    }
+
+    var expectedMarginBottom = checkAttribute(output, node, "data-expected-margin-bottom");
+    if (expectedMarginBottom) {
+        var actualMarginBottom = getComputedStyle(node).marginBottom;
+        // Trim the unit "px" from the output.
+        actualMarginBottom = actualMarginBottom.slice(0, -2);
+        assert_equals(actualMarginBottom, expectedMarginBottom, prefix + "margin-bottom");
+    }
+
+    var expectedMarginLeft = checkAttribute(output, node, "data-expected-margin-left");
+    if (expectedMarginLeft) {
+        var actualMarginLeft = getComputedStyle(node).marginLeft;
+        // Trim the unit "px" from the output.
+        actualMarginLeft = actualMarginLeft.slice(0, -2);
+        assert_equals(actualMarginLeft, expectedMarginLeft, prefix + "margin-left");
+    }
+
+    var expectedMarginRight = checkAttribute(output, node, "data-expected-margin-right");
+    if (expectedMarginRight) {
+        var actualMarginRight = getComputedStyle(node).marginRight;
+        // Trim the unit "px" from the output.
+        actualMarginRight = actualMarginRight.slice(0, -2);
+        assert_equals(actualMarginRight, expectedMarginRight, prefix + "margin-right");
+    }
+
+    return output.checked;
+}
+
+var testNumber = 0;
+var highlightError = false; // displays outline around failed test element.
+var printDomOnError = true; // prints dom when test fails.
+
+window.checkLayout = function(selectorList, callDone = true)
+{
+    if (!selectorList) {
+        console.error("You must provide a CSS selector of nodes to check.");
+        return;
+    }
+    var nodes = document.querySelectorAll(selectorList);
+    nodes = Array.prototype.slice.call(nodes);
+    var checkedLayout = false;
+    Array.prototype.forEach.call(nodes, function(node) {
+        test(function(t) {
+            var container = node.parentNode.className == 'container' ? node.parentNode : node;
+            var prefix =
+                printDomOnError ? '\n' + container.outerHTML + '\n' : '';
+            var passed = false;
+            try {
+                checkedLayout |= checkExpectedValues(t, node.parentNode, prefix);
+                checkedLayout |= checkSubtreeExpectedValues(t, node, prefix);
+                passed = true;
+            } finally {
+              if (!passed && highlightError) {
+                if (!document.getElementById('testharness_error_css')) {
+                  var style = document.createElement('style');
+                  style.id = 'testharness_error_css';
+                  style.textContent = '.testharness_error { outline: red dotted 2px !important; }';
+                  document.body.appendChild(style);
+                }
+                if (node)
+                  node.classList.add('testharness_error');
+              }
+                checkedLayout |= !passed;
+            }
+        }, selectorList + ' ' + String(++testNumber));
+    });
+    if (!checkedLayout) {
+        console.error("No valid data-* attributes found in selector list : " + selectorList);
+    }
+    if (callDone)
+        done();
+};
+
+})();
diff --git a/test/wpt/tests/resources/check-layout.js b/test/wpt/tests/resources/check-layout.js
new file mode 100644
index 0000000..8634481
--- /dev/null
+++ b/test/wpt/tests/resources/check-layout.js
@@ -0,0 +1,245 @@
+(function() {
+
+function insertAfter(nodeToAdd, referenceNode)
+{
+    if (referenceNode == document.body) {
+        document.body.appendChild(nodeToAdd);
+        return;
+    }
+
+    if (referenceNode.nextSibling)
+        referenceNode.parentNode.insertBefore(nodeToAdd, referenceNode.nextSibling);
+    else
+        referenceNode.parentNode.appendChild(nodeToAdd);
+}
+
+function positionedAncestor(node)
+{
+    var ancestor = node.parentNode;
+    while (getComputedStyle(ancestor).position == 'static')
+        ancestor = ancestor.parentNode;
+    return ancestor;
+}
+
+function checkSubtreeExpectedValues(parent, failures)
+{
+    var checkedLayout = checkExpectedValues(parent, failures);
+    Array.prototype.forEach.call(parent.childNodes, function(node) {
+        checkedLayout |= checkSubtreeExpectedValues(node, failures);
+    });
+    return checkedLayout;
+}
+
+function checkAttribute(output, node, attribute)
+{
+    var result = node.getAttribute && node.getAttribute(attribute);
+    output.checked |= !!result;
+    return result;
+}
+
+function checkExpectedValues(node, failures)
+{
+    var output = { checked: false };
+    var expectedWidth = checkAttribute(output, node, "data-expected-width");
+    if (expectedWidth) {
+        if (isNaN(expectedWidth) || Math.abs(node.offsetWidth - expectedWidth) >= 1)
+            failures.push("Expected " + expectedWidth + " for width, but got " + node.offsetWidth + ". ");
+    }
+
+    var expectedHeight = checkAttribute(output, node, "data-expected-height");
+    if (expectedHeight) {
+        if (isNaN(expectedHeight) || Math.abs(node.offsetHeight - expectedHeight) >= 1)
+            failures.push("Expected " + expectedHeight + " for height, but got " + node.offsetHeight + ". ");
+    }
+
+    var expectedOffset = checkAttribute(output, node, "data-offset-x");
+    if (expectedOffset) {
+        if (isNaN(expectedOffset) || Math.abs(node.offsetLeft - expectedOffset) >= 1)
+            failures.push("Expected " + expectedOffset + " for offsetLeft, but got " + node.offsetLeft + ". ");
+    }
+
+    var expectedOffset = checkAttribute(output, node, "data-offset-y");
+    if (expectedOffset) {
+        if (isNaN(expectedOffset) || Math.abs(node.offsetTop - expectedOffset) >= 1)
+            failures.push("Expected " + expectedOffset + " for offsetTop, but got " + node.offsetTop + ". ");
+    }
+
+    var expectedOffset = checkAttribute(output, node, "data-positioned-offset-x");
+    if (expectedOffset) {
+        var actualOffset = node.getBoundingClientRect().left - positionedAncestor(node).getBoundingClientRect().left;
+        if (isNaN(expectedOffset) || Math.abs(actualOffset - expectedOffset) >= 1)
+            failures.push("Expected " + expectedOffset + " for getBoundingClientRect().left offset, but got " + actualOffset + ". ");
+    }
+
+    var expectedOffset = checkAttribute(output, node, "data-positioned-offset-y");
+    if (expectedOffset) {
+        var actualOffset = node.getBoundingClientRect().top - positionedAncestor(node).getBoundingClientRect().top;
+        if (isNaN(expectedOffset) || Math.abs(actualOffset - expectedOffset) >= 1)
+            failures.push("Expected " + expectedOffset + " for getBoundingClientRect().top offset, but got " + actualOffset + ". ");
+    }
+
+    var expectedWidth = checkAttribute(output, node, "data-expected-client-width");
+    if (expectedWidth) {
+        if (isNaN(expectedWidth) || Math.abs(node.clientWidth - expectedWidth) >= 1)
+            failures.push("Expected " + expectedWidth + " for clientWidth, but got " + node.clientWidth + ". ");
+    }
+
+    var expectedHeight = checkAttribute(output, node, "data-expected-client-height");
+    if (expectedHeight) {
+        if (isNaN(expectedHeight) || Math.abs(node.clientHeight - expectedHeight) >= 1)
+            failures.push("Expected " + expectedHeight + " for clientHeight, but got " + node.clientHeight + ". ");
+    }
+
+    var expectedWidth = checkAttribute(output, node, "data-expected-scroll-width");
+    if (expectedWidth) {
+        if (isNaN(expectedWidth) || Math.abs(node.scrollWidth - expectedWidth) >= 1)
+            failures.push("Expected " + expectedWidth + " for scrollWidth, but got " + node.scrollWidth + ". ");
+    }
+
+    var expectedHeight = checkAttribute(output, node, "data-expected-scroll-height");
+    if (expectedHeight) {
+        if (isNaN(expectedHeight) || Math.abs(node.scrollHeight - expectedHeight) >= 1)
+            failures.push("Expected " + expectedHeight + " for scrollHeight, but got " + node.scrollHeight + ". ");
+    }
+
+    var expectedOffset = checkAttribute(output, node, "data-total-x");
+    if (expectedOffset) {
+        var totalLeft = node.clientLeft + node.offsetLeft;
+        if (isNaN(expectedOffset) || Math.abs(totalLeft - expectedOffset) >= 1)
+            failures.push("Expected " + expectedOffset + " for clientLeft+offsetLeft, but got " + totalLeft + ", clientLeft: " + node.clientLeft + ", offsetLeft: " + node.offsetLeft + ". ");
+    }
+
+    var expectedOffset = checkAttribute(output, node, "data-total-y");
+    if (expectedOffset) {
+        var totalTop = node.clientTop + node.offsetTop;
+        if (isNaN(expectedOffset) || Math.abs(totalTop - expectedOffset) >= 1)
+            failures.push("Expected " + expectedOffset + " for clientTop+offsetTop, but got " + totalTop + ", clientTop: " + node.clientTop + ", + offsetTop: " + node.offsetTop + ". ");
+    }
+
+    var expectedDisplay = checkAttribute(output, node, "data-expected-display");
+    if (expectedDisplay) {
+        var actualDisplay = getComputedStyle(node).display;
+        if (actualDisplay != expectedDisplay)
+            failures.push("Expected " + expectedDisplay + " for display, but got " + actualDisplay + ". ");
+    }
+
+    var expectedPaddingTop = checkAttribute(output, node, "data-expected-padding-top");
+    if (expectedPaddingTop) {
+        var actualPaddingTop = getComputedStyle(node).paddingTop;
+        // Trim the unit "px" from the output.
+        actualPaddingTop = actualPaddingTop.substring(0, actualPaddingTop.length - 2);
+        if (actualPaddingTop != expectedPaddingTop)
+            failures.push("Expected " + expectedPaddingTop + " for padding-top, but got " + actualPaddingTop + ". ");
+    }
+
+    var expectedPaddingBottom = checkAttribute(output, node, "data-expected-padding-bottom");
+    if (expectedPaddingBottom) {
+        var actualPaddingBottom = getComputedStyle(node).paddingBottom;
+        // Trim the unit "px" from the output.
+        actualPaddingBottom = actualPaddingBottom.substring(0, actualPaddingBottom.length - 2);
+        if (actualPaddingBottom != expectedPaddingBottom)
+            failures.push("Expected " + expectedPaddingBottom + " for padding-bottom, but got " + actualPaddingBottom + ". ");
+    }
+
+    var expectedPaddingLeft = checkAttribute(output, node, "data-expected-padding-left");
+    if (expectedPaddingLeft) {
+        var actualPaddingLeft = getComputedStyle(node).paddingLeft;
+        // Trim the unit "px" from the output.
+        actualPaddingLeft = actualPaddingLeft.substring(0, actualPaddingLeft.length - 2);
+        if (actualPaddingLeft != expectedPaddingLeft)
+            failures.push("Expected " + expectedPaddingLeft + " for padding-left, but got " + actualPaddingLeft + ". ");
+    }
+
+    var expectedPaddingRight = checkAttribute(output, node, "data-expected-padding-right");
+    if (expectedPaddingRight) {
+        var actualPaddingRight = getComputedStyle(node).paddingRight;
+        // Trim the unit "px" from the output.
+        actualPaddingRight = actualPaddingRight.substring(0, actualPaddingRight.length - 2);
+        if (actualPaddingRight != expectedPaddingRight)
+            failures.push("Expected " + expectedPaddingRight + " for padding-right, but got " + actualPaddingRight + ". ");
+    }
+
+    var expectedMarginTop = checkAttribute(output, node, "data-expected-margin-top");
+    if (expectedMarginTop) {
+        var actualMarginTop = getComputedStyle(node).marginTop;
+        // Trim the unit "px" from the output.
+        actualMarginTop = actualMarginTop.substring(0, actualMarginTop.length - 2);
+        if (actualMarginTop != expectedMarginTop)
+            failures.push("Expected " + expectedMarginTop + " for margin-top, but got " + actualMarginTop + ". ");
+    }
+
+    var expectedMarginBottom = checkAttribute(output, node, "data-expected-margin-bottom");
+    if (expectedMarginBottom) {
+        var actualMarginBottom = getComputedStyle(node).marginBottom;
+        // Trim the unit "px" from the output.
+        actualMarginBottom = actualMarginBottom.substring(0, actualMarginBottom.length - 2);
+        if (actualMarginBottom != expectedMarginBottom)
+            failures.push("Expected " + expectedMarginBottom + " for margin-bottom, but got " + actualMarginBottom + ". ");
+    }
+
+    var expectedMarginLeft = checkAttribute(output, node, "data-expected-margin-left");
+    if (expectedMarginLeft) {
+        var actualMarginLeft = getComputedStyle(node).marginLeft;
+        // Trim the unit "px" from the output.
+        actualMarginLeft = actualMarginLeft.substring(0, actualMarginLeft.length - 2);
+        if (actualMarginLeft != expectedMarginLeft)
+            failures.push("Expected " + expectedMarginLeft + " for margin-left, but got " + actualMarginLeft + ". ");
+    }
+
+    var expectedMarginRight = checkAttribute(output, node, "data-expected-margin-right");
+    if (expectedMarginRight) {
+        var actualMarginRight = getComputedStyle(node).marginRight;
+        // Trim the unit "px" from the output.
+        actualMarginRight = actualMarginRight.substring(0, actualMarginRight.length - 2);
+        if (actualMarginRight != expectedMarginRight)
+            failures.push("Expected " + expectedMarginRight + " for margin-right, but got " + actualMarginRight + ". ");
+    }
+
+    return output.checked;
+}
+
+window.checkLayout = function(selectorList, outputContainer)
+{
+    var result = true;
+    if (!selectorList) {
+        document.body.appendChild(document.createTextNode("You must provide a CSS selector of nodes to check."));
+        return;
+    }
+    var nodes = document.querySelectorAll(selectorList);
+    nodes = Array.prototype.slice.call(nodes);
+    nodes.reverse();
+    var checkedLayout = false;
+    Array.prototype.forEach.call(nodes, function(node) {
+        var failures = [];
+        checkedLayout |= checkExpectedValues(node.parentNode, failures);
+        checkedLayout |= checkSubtreeExpectedValues(node, failures);
+
+        var container = node.parentNode.className == 'container' ? node.parentNode : node;
+
+        var pre = document.createElement('pre');
+        if (failures.length) {
+            pre.className = 'FAIL';
+            result = false;
+        }
+        pre.appendChild(document.createTextNode(failures.length ? "FAIL:\n" + failures.join('\n') + '\n\n' + container.outerHTML : "PASS"));
+
+        var referenceNode = container;
+        if (outputContainer) {
+            if (!outputContainer.lastChild) {
+                // Inserting a text node so we have something to insertAfter.
+                outputContainer.textContent = " ";
+            }
+            referenceNode = outputContainer.lastChild;
+        }
+        insertAfter(pre, referenceNode);
+    });
+
+    if (!checkedLayout) {
+        document.body.appendChild(document.createTextNode("FAIL: No valid data-* attributes found in selector list : " + selectorList));
+        return false;
+    }
+
+    return result;
+}
+
+})();
diff --git a/test/wpt/tests/resources/chromium/README.md b/test/wpt/tests/resources/chromium/README.md
new file mode 100644
index 0000000..be090b3
--- /dev/null
+++ b/test/wpt/tests/resources/chromium/README.md
@@ -0,0 +1,7 @@
+This directory contains Chromium-specific test resources, including mocks for
+test-only APIs implemented with
+[MojoJS](https://chromium.googlesource.com/chromium/src/+/main/mojo/public/js/README.md).
+
+Please do **not** copy `*.mojom.m.js` into this directory. Follow this doc if you
+want to add new MojoJS-backed mocks:
+https://chromium.googlesource.com/chromium/src/+/main/docs/testing/web_platform_tests.md#mojojs
diff --git a/test/wpt/tests/resources/chromium/contacts_manager_mock.js b/test/wpt/tests/resources/chromium/contacts_manager_mock.js
new file mode 100644
index 0000000..0496852
--- /dev/null
+++ b/test/wpt/tests/resources/chromium/contacts_manager_mock.js
@@ -0,0 +1,90 @@
+// Copyright 2018 The Chromium Authors
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+import {ContactsManager, ContactsManagerReceiver} from '/gen/third_party/blink/public/mojom/contacts/contacts_manager.mojom.m.js';
+
+self.WebContactsTest = (() => {
+  class MockContacts {
+    constructor() {
+      this.receiver_ = new ContactsManagerReceiver(this);
+
+      this.interceptor_ =
+          new MojoInterfaceInterceptor(ContactsManager.$interfaceName);
+      this.interceptor_.oninterfacerequest =
+          e => this.receiver_.$.bindHandle(e.handle);
+      this.interceptor_.start();
+
+      this.selectedContacts_ = [];
+    }
+
+    formatAddress_(address) {
+      // These are all required fields in the mojo definition.
+      return {
+        country: address.country || '',
+        addressLine: address.addressLine || [],
+        region: address.region || '',
+        city: address.city || '',
+        dependentLocality: address.dependentLocality || '',
+        postalCode: address.postCode || '',
+        sortingCode: address.sortingCode || '',
+        organization: address.organization || '',
+        recipient: address.recipient || '',
+        phone: address.phone || '',
+      };
+    }
+
+    async select(multiple, includeNames, includeEmails, includeTel, includeAddresses, includeIcons) {
+      if (this.selectedContacts_ === null)
+        return {contacts: null};
+
+      const contactInfos = await Promise.all(this.selectedContacts_.map(async contact => {
+        const contactInfo = {};
+        if (includeNames)
+          contactInfo.name = contact.name || [];
+        if (includeEmails)
+          contactInfo.email = contact.email || [];
+        if (includeTel)
+          contactInfo.tel = contact.tel || [];
+        if (includeAddresses) {
+          contactInfo.address = (contact.address || []).map(address => this.formatAddress_(address));
+        }
+        if (includeIcons) {
+          contactInfo.icon = await Promise.all(
+            (contact.icon || []).map(async blob => ({
+              mimeType: blob.type,
+              data: (await blob.text()).split('').map(s => s.charCodeAt(0)),
+            })));
+        }
+        return contactInfo;
+      }));
+
+      if (!contactInfos.length) return {contacts: []};
+      if (!multiple) return {contacts: [contactInfos[0]]};
+      return {contacts: contactInfos};
+    }
+
+    setSelectedContacts(contacts) {
+      this.selectedContacts_ = contacts;
+    }
+
+    reset() {
+      this.receiver_.$.close();
+      this.interceptor_.stop();
+    }
+  }
+
+  const mockContacts = new MockContacts();
+
+  class ContactsTestChromium {
+    constructor() {
+      Object.freeze(this); // Make it immutable.
+    }
+
+    setSelectedContacts(contacts) {
+      mockContacts.setSelectedContacts(contacts);
+    }
+  }
+
+  return ContactsTestChromium;
+})();
diff --git a/test/wpt/tests/resources/chromium/content-index-helpers.js b/test/wpt/tests/resources/chromium/content-index-helpers.js
new file mode 100644
index 0000000..936fe84
--- /dev/null
+++ b/test/wpt/tests/resources/chromium/content-index-helpers.js
@@ -0,0 +1,9 @@
+import {ContentIndexService} from '/gen/third_party/blink/public/mojom/content_index/content_index.mojom.m.js';
+
+// Returns a promise if the chromium based browser fetches icons for
+// content-index.
+export async function fetchesIcons() {
+  const remote = ContentIndexService.getRemote();
+  const {iconSizes} = await remote.getIconSizes();
+  return iconSizes.length > 0;
+};
diff --git a/test/wpt/tests/resources/chromium/enable-hyperlink-auditing.js b/test/wpt/tests/resources/chromium/enable-hyperlink-auditing.js
new file mode 100644
index 0000000..263f651
--- /dev/null
+++ b/test/wpt/tests/resources/chromium/enable-hyperlink-auditing.js
@@ -0,0 +1,2 @@
+if (window.testRunner)
+  testRunner.overridePreference("WebKitHyperlinkAuditingEnabled", 1);
diff --git a/test/wpt/tests/resources/chromium/fake-hid.js b/test/wpt/tests/resources/chromium/fake-hid.js
new file mode 100644
index 0000000..70a0149
--- /dev/null
+++ b/test/wpt/tests/resources/chromium/fake-hid.js
@@ -0,0 +1,297 @@
+import {HidConnectionReceiver, HidDeviceInfo} from '/gen/services/device/public/mojom/hid.mojom.m.js';
+import {HidService, HidServiceReceiver} from '/gen/third_party/blink/public/mojom/hid/hid.mojom.m.js';
+
+// Fake implementation of device.mojom.HidConnection. HidConnection represents
+// an open connection to a HID device and can be used to send and receive
+// reports.
+class FakeHidConnection {
+  constructor(client) {
+    this.client_ = client;
+    this.receiver_ = new HidConnectionReceiver(this);
+    this.expectedWrites_ = [];
+    this.expectedGetFeatureReports_ = [];
+    this.expectedSendFeatureReports_ = [];
+  }
+
+  bindNewPipeAndPassRemote() {
+    return this.receiver_.$.bindNewPipeAndPassRemote();
+  }
+
+  // Simulate an input report sent from the device to the host. The connection
+  // client's onInputReport method will be called with the provided |reportId|
+  // and |buffer|.
+  simulateInputReport(reportId, reportData) {
+    if (this.client_) {
+      this.client_.onInputReport(reportId, reportData);
+    }
+  }
+
+  // Specify the result for an expected call to write. If |success| is true the
+  // write will be successful, otherwise it will simulate a failure. The
+  // parameters of the next write call must match |reportId| and |buffer|.
+  queueExpectedWrite(success, reportId, reportData) {
+    this.expectedWrites_.push({
+      params: {reportId, data: reportData},
+      result: {success},
+    });
+  }
+
+  // Specify the result for an expected call to getFeatureReport. If |success|
+  // is true the operation is successful, otherwise it will simulate a failure.
+  // The parameter of the next getFeatureReport call must match |reportId|.
+  queueExpectedGetFeatureReport(success, reportId, reportData) {
+    this.expectedGetFeatureReports_.push({
+      params: {reportId},
+      result: {success, buffer: reportData},
+    });
+  }
+
+  // Specify the result for an expected call to sendFeatureReport. If |success|
+  // is true the operation is successful, otherwise it will simulate a failure.
+  // The parameters of the next sendFeatureReport call must match |reportId| and
+  // |buffer|.
+  queueExpectedSendFeatureReport(success, reportId, reportData) {
+    this.expectedSendFeatureReports_.push({
+      params: {reportId, data: reportData},
+      result: {success},
+    });
+  }
+
+  // Asserts that there are no more expected operations.
+  assertExpectationsMet() {
+    assert_equals(this.expectedWrites_.length, 0);
+    assert_equals(this.expectedGetFeatureReports_.length, 0);
+    assert_equals(this.expectedSendFeatureReports_.length, 0);
+  }
+
+  read() {}
+
+  // Implementation of HidConnection::Write. Causes an assertion failure if
+  // there are no expected write operations, or if the parameters do not match
+  // the expected call.
+  async write(reportId, buffer) {
+    let expectedWrite = this.expectedWrites_.shift();
+    assert_not_equals(expectedWrite, undefined);
+    assert_equals(reportId, expectedWrite.params.reportId);
+    let actual = new Uint8Array(buffer);
+    compareDataViews(
+        new DataView(actual.buffer, actual.byteOffset),
+        new DataView(
+            expectedWrite.params.data.buffer,
+            expectedWrite.params.data.byteOffset));
+    return expectedWrite.result;
+  }
+
+  // Implementation of HidConnection::GetFeatureReport. Causes an assertion
+  // failure if there are no expected write operations, or if the parameters do
+  // not match the expected call.
+  async getFeatureReport(reportId) {
+    let expectedGetFeatureReport = this.expectedGetFeatureReports_.shift();
+    assert_not_equals(expectedGetFeatureReport, undefined);
+    assert_equals(reportId, expectedGetFeatureReport.params.reportId);
+    return expectedGetFeatureReport.result;
+  }
+
+  // Implementation of HidConnection::SendFeatureReport. Causes an assertion
+  // failure if there are no expected write operations, or if the parameters do
+  // not match the expected call.
+  async sendFeatureReport(reportId, buffer) {
+    let expectedSendFeatureReport = this.expectedSendFeatureReports_.shift();
+    assert_not_equals(expectedSendFeatureReport, undefined);
+    assert_equals(reportId, expectedSendFeatureReport.params.reportId);
+    let actual = new Uint8Array(buffer);
+    compareDataViews(
+        new DataView(actual.buffer, actual.byteOffset),
+        new DataView(
+            expectedSendFeatureReport.params.data.buffer,
+            expectedSendFeatureReport.params.data.byteOffset));
+    return expectedSendFeatureReport.result;
+  }
+}
+
+
+// A fake implementation of the HidService mojo interface. HidService manages
+// HID device access for clients in the render process. Typically, when a client
+// requests access to a HID device a chooser dialog is shown with a list of
+// available HID devices. Selecting a device from the chooser also grants
+// permission for the client to access that device.
+//
+// The fake implementation allows tests to simulate connected devices. It also
+// skips the chooser dialog and instead allows tests to specify which device
+// should be selected. All devices are treated as if the user had already
+// granted permission. It is possible to revoke permission with forget() later.
+class FakeHidService {
+  constructor() {
+    this.interceptor_ = new MojoInterfaceInterceptor(HidService.$interfaceName);
+    this.interceptor_.oninterfacerequest = e => this.bind(e.handle);
+    this.receiver_ = new HidServiceReceiver(this);
+    this.nextGuidValue_ = 0;
+    this.simulateConnectFailure_ = false;
+    this.reset();
+  }
+
+  start() {
+    this.interceptor_.start();
+  }
+
+  stop() {
+    this.interceptor_.stop();
+  }
+
+  reset() {
+    this.devices_ = new Map();
+    this.allowedDevices_ = new Map();
+    this.fakeConnections_ = new Map();
+    this.selectedDevices_ = [];
+  }
+
+  // Creates and returns a HidDeviceInfo with the specified device IDs.
+  makeDevice(vendorId, productId) {
+    let guidValue = ++this.nextGuidValue_;
+    let info = new HidDeviceInfo();
+    info.guid = 'guid-' + guidValue.toString();
+    info.physicalDeviceId = 'physical-device-id-' + guidValue.toString();
+    info.vendorId = vendorId;
+    info.productId = productId;
+    info.productName = 'product name';
+    info.serialNumber = '0';
+    info.reportDescriptor = new Uint8Array();
+    info.collections = [];
+    info.deviceNode = 'device node';
+    return info;
+  }
+
+  // Simulates a connected device the client has already been granted permission
+  // to. Returns the key used to store the device in the map. The key is either
+  // the physical device ID, or the device GUID if it has no physical device ID.
+  addDevice(deviceInfo, grantPermission = true) {
+    let key = deviceInfo.physicalDeviceId;
+    if (key.length === 0)
+      key = deviceInfo.guid;
+
+    let devices = this.devices_.get(key) || [];
+    devices.push(deviceInfo);
+    this.devices_.set(key, devices);
+
+    if (grantPermission) {
+      let allowedDevices = this.allowedDevices_.get(key) || [];
+      allowedDevices.push(deviceInfo);
+      this.allowedDevices_.set(key, allowedDevices);
+    }
+
+    if (this.client_)
+      this.client_.deviceAdded(deviceInfo);
+    return key;
+  }
+
+  // Simulates disconnecting a connected device.
+  removeDevice(key) {
+    let devices = this.devices_.get(key);
+    this.devices_.delete(key);
+    if (this.client_ && devices) {
+      devices.forEach(deviceInfo => {
+        this.client_.deviceRemoved(deviceInfo);
+      });
+    }
+  }
+
+  // Simulates updating the device information for a connected device.
+  changeDevice(deviceInfo) {
+    let key = deviceInfo.physicalDeviceId;
+    if (key.length === 0)
+      key = deviceInfo.guid;
+
+    let devices = this.devices_.get(key) || [];
+    let i = devices.length;
+    while (i--) {
+      if (devices[i].guid == deviceInfo.guid)
+        devices.splice(i, 1);
+    }
+    devices.push(deviceInfo);
+    this.devices_.set(key, devices);
+
+    let allowedDevices = this.allowedDevices_.get(key) || [];
+    let j = allowedDevices.length;
+    while (j--) {
+      if (allowedDevices[j].guid == deviceInfo.guid)
+        allowedDevices.splice(j, 1);
+    }
+    allowedDevices.push(deviceInfo);
+    this.allowedDevices_.set(key, allowedDevices);
+
+    if (this.client_)
+      this.client_.deviceChanged(deviceInfo);
+    return key;
+  }
+
+  // Sets a flag that causes the next call to connect() to fail.
+  simulateConnectFailure() {
+    this.simulateConnectFailure_ = true;
+  }
+
+  // Sets the key of the device that will be returned as the selected item the
+  // next time requestDevice is called. The device with this key must have been
+  // previously added with addDevice.
+  setSelectedDevice(key) {
+    this.selectedDevices_ = this.devices_.get(key);
+  }
+
+  // Returns the fake HidConnection object for this device, if there is one. A
+  // connection is created once the device is opened.
+  getFakeConnection(guid) {
+    return this.fakeConnections_.get(guid);
+  }
+
+  bind(handle) {
+    this.receiver_.$.bindHandle(handle);
+  }
+
+  registerClient(client) {
+    this.client_ = client;
+  }
+
+  // Returns an array of connected devices the client has already been granted
+  // permission to access.
+  async getDevices() {
+    let devices = [];
+    this.allowedDevices_.forEach((value) => {
+      devices = devices.concat(value);
+    });
+    return {devices};
+  }
+
+  // Simulates a device chooser prompt, returning |selectedDevices_| as the
+  // simulated selection. |options| is ignored.
+  async requestDevice(options) {
+    return {devices: this.selectedDevices_};
+  }
+
+  // Returns a fake connection to the device with the specified GUID. If
+  // |connectionClient| is not null, its onInputReport method will be called
+  // when input reports are received. If simulateConnectFailure() was called
+  // then a null connection is returned instead, indicating failure.
+  async connect(guid, connectionClient) {
+    if (this.simulateConnectFailure_) {
+      this.simulateConnectFailure_ = false;
+      return {connection: null};
+    }
+    const fakeConnection = new FakeHidConnection(connectionClient);
+    this.fakeConnections_.set(guid, fakeConnection);
+    return {connection: fakeConnection.bindNewPipeAndPassRemote()};
+  }
+
+  // Removes the allowed device.
+  async forget(deviceInfo) {
+    for (const [key, value] of this.allowedDevices_) {
+      for (const device of value) {
+        if (device.guid == deviceInfo.guid) {
+          this.allowedDevices_.delete(key);
+          break;
+        }
+      }
+    }
+    return {success: true};
+  }
+}
+
+export const fakeHidService = new FakeHidService();
diff --git a/test/wpt/tests/resources/chromium/fake-serial.js b/test/wpt/tests/resources/chromium/fake-serial.js
new file mode 100644
index 0000000..e1e4d57
--- /dev/null
+++ b/test/wpt/tests/resources/chromium/fake-serial.js
@@ -0,0 +1,443 @@
+import {SerialPortFlushMode, SerialPortRemote, SerialReceiveError, SerialPortReceiver, SerialSendError} from '/gen/services/device/public/mojom/serial.mojom.m.js';
+import {SerialService, SerialServiceReceiver} from '/gen/third_party/blink/public/mojom/serial/serial.mojom.m.js';
+
+// Implementation of an UnderlyingSource to create a ReadableStream from a Mojo
+// data pipe consumer handle.
+class DataPipeSource {
+  constructor(consumer) {
+    this.consumer_ = consumer;
+  }
+
+  async pull(controller) {
+    let chunk = new ArrayBuffer(64);
+    let {result, numBytes} = this.consumer_.readData(chunk);
+    if (result == Mojo.RESULT_OK) {
+      controller.enqueue(new Uint8Array(chunk, 0, numBytes));
+      return;
+    } else if (result == Mojo.RESULT_FAILED_PRECONDITION) {
+      controller.close();
+      return;
+    } else if (result == Mojo.RESULT_SHOULD_WAIT) {
+      await this.readable();
+      return this.pull(controller);
+    }
+  }
+
+  cancel() {
+    if (this.watcher_)
+      this.watcher_.cancel();
+    this.consumer_.close();
+  }
+
+  readable() {
+    return new Promise((resolve) => {
+      this.watcher_ =
+          this.consumer_.watch({ readable: true, peerClosed: true }, () => {
+            this.watcher_.cancel();
+            this.watcher_ = undefined;
+            resolve();
+          });
+    });
+  }
+}
+
+// Implementation of an UnderlyingSink to create a WritableStream from a Mojo
+// data pipe producer handle.
+class DataPipeSink {
+  constructor(producer) {
+    this._producer = producer;
+  }
+
+  async write(chunk, controller) {
+    while (true) {
+      let {result, numBytes} = this._producer.writeData(chunk);
+      if (result == Mojo.RESULT_OK) {
+        if (numBytes == chunk.byteLength) {
+          return;
+        }
+        chunk = chunk.slice(numBytes);
+      } else if (result == Mojo.RESULT_FAILED_PRECONDITION) {
+        throw new DOMException('The pipe is closed.', 'InvalidStateError');
+      } else if (result == Mojo.RESULT_SHOULD_WAIT) {
+        await this.writable();
+      }
+    }
+  }
+
+  close() {
+    assert_equals(undefined, this._watcher);
+    this._producer.close();
+  }
+
+  abort(reason) {
+    if (this._watcher)
+      this._watcher.cancel();
+    this._producer.close();
+  }
+
+  writable() {
+    return new Promise((resolve) => {
+      this._watcher =
+          this._producer.watch({ writable: true, peerClosed: true }, () => {
+            this._watcher.cancel();
+            this._watcher = undefined;
+            resolve();
+          });
+    });
+  }
+}
+
+// Implementation of device.mojom.SerialPort.
+class FakeSerialPort {
+  constructor() {
+    this.inputSignals_ = {
+      dataCarrierDetect: false,
+      clearToSend: false,
+      ringIndicator: false,
+      dataSetReady: false
+    };
+    this.inputSignalFailure_ = false;
+    this.outputSignals_ = {
+      dataTerminalReady: false,
+      requestToSend: false,
+      break: false
+    };
+    this.outputSignalFailure_ = false;
+  }
+
+  open(options, client) {
+    if (this.receiver_ !== undefined) {
+      // Port already open.
+      return null;
+    }
+
+    let port = new SerialPortRemote();
+    this.receiver_ = new SerialPortReceiver(this);
+    this.receiver_.$.bindHandle(port.$.bindNewPipeAndPassReceiver().handle);
+
+    this.options_ = options;
+    this.client_ = client;
+    // OS typically sets DTR on open.
+    this.outputSignals_.dataTerminalReady = true;
+
+    return port;
+  }
+
+  write(data) {
+    return this.writer_.write(data);
+  }
+
+  read() {
+    return this.reader_.read();
+  }
+
+  // Reads from the port until at least |targetLength| is read or the stream is
+  // closed. The data is returned as a combined Uint8Array.
+  readWithLength(targetLength) {
+    return readWithLength(this.reader_, targetLength);
+  }
+
+  simulateReadError(error) {
+    this.writer_.close();
+    this.writer_.releaseLock();
+    this.writer_ = undefined;
+    this.writable_ = undefined;
+    this.client_.onReadError(error);
+  }
+
+  simulateParityError() {
+    this.simulateReadError(SerialReceiveError.PARITY_ERROR);
+  }
+
+  simulateDisconnectOnRead() {
+    this.simulateReadError(SerialReceiveError.DISCONNECTED);
+  }
+
+  simulateWriteError(error) {
+    this.reader_.cancel();
+    this.reader_ = undefined;
+    this.readable_ = undefined;
+    this.client_.onSendError(error);
+  }
+
+  simulateSystemErrorOnWrite() {
+    this.simulateWriteError(SerialSendError.SYSTEM_ERROR);
+  }
+
+  simulateDisconnectOnWrite() {
+    this.simulateWriteError(SerialSendError.DISCONNECTED);
+  }
+
+  simulateInputSignals(signals) {
+    this.inputSignals_ = signals;
+  }
+
+  simulateInputSignalFailure(fail) {
+    this.inputSignalFailure_ = fail;
+  }
+
+  get outputSignals() {
+    return this.outputSignals_;
+  }
+
+  simulateOutputSignalFailure(fail) {
+    this.outputSignalFailure_ = fail;
+  }
+
+  writable() {
+    if (this.writable_)
+      return Promise.resolve();
+
+    if (!this.writablePromise_) {
+      this.writablePromise_ = new Promise((resolve) => {
+        this.writableResolver_ = resolve;
+      });
+    }
+
+    return this.writablePromise_;
+  }
+
+  readable() {
+    if (this.readable_)
+      return Promise.resolve();
+
+    if (!this.readablePromise_) {
+      this.readablePromise_ = new Promise((resolve) => {
+        this.readableResolver_ = resolve;
+      });
+    }
+
+    return this.readablePromise_;
+  }
+
+  async startWriting(in_stream) {
+    this.readable_ = new ReadableStream(new DataPipeSource(in_stream));
+    this.reader_ = this.readable_.getReader();
+    if (this.readableResolver_) {
+      this.readableResolver_();
+      this.readableResolver_ = undefined;
+      this.readablePromise_ = undefined;
+    }
+  }
+
+  async startReading(out_stream) {
+    this.writable_ = new WritableStream(new DataPipeSink(out_stream));
+    this.writer_ = this.writable_.getWriter();
+    if (this.writableResolver_) {
+      this.writableResolver_();
+      this.writableResolver_ = undefined;
+      this.writablePromise_ = undefined;
+    }
+  }
+
+  async flush(mode) {
+    switch (mode) {
+      case SerialPortFlushMode.kReceive:
+        this.writer_.abort();
+        this.writer_.releaseLock();
+        this.writer_ = undefined;
+        this.writable_ = undefined;
+        break;
+      case SerialPortFlushMode.kTransmit:
+        this.reader_.cancel();
+        this.reader_ = undefined;
+        this.readable_ = undefined;
+        break;
+    }
+  }
+
+  async drain() {
+    await this.reader_.closed;
+  }
+
+  async getControlSignals() {
+    if (this.inputSignalFailure_) {
+      return {signals: null};
+    }
+
+    const signals = {
+      dcd: this.inputSignals_.dataCarrierDetect,
+      cts: this.inputSignals_.clearToSend,
+      ri: this.inputSignals_.ringIndicator,
+      dsr: this.inputSignals_.dataSetReady
+    };
+    return {signals};
+  }
+
+  async setControlSignals(signals) {
+    if (this.outputSignalFailure_) {
+      return {success: false};
+    }
+
+    if (signals.hasDtr) {
+      this.outputSignals_.dataTerminalReady = signals.dtr;
+    }
+    if (signals.hasRts) {
+      this.outputSignals_.requestToSend = signals.rts;
+    }
+    if (signals.hasBrk) {
+      this.outputSignals_.break = signals.brk;
+    }
+    return { success: true };
+  }
+
+  async configurePort(options) {
+    this.options_ = options;
+    return { success: true };
+  }
+
+  async getPortInfo() {
+    return {
+      bitrate: this.options_.bitrate,
+      dataBits: this.options_.datBits,
+      parityBit: this.options_.parityBit,
+      stopBits: this.options_.stopBits,
+      ctsFlowControl:
+          this.options_.hasCtsFlowControl && this.options_.ctsFlowControl,
+    };
+  }
+
+  async close() {
+    // OS typically clears DTR on close.
+    this.outputSignals_.dataTerminalReady = false;
+    if (this.writer_) {
+      this.writer_.close();
+      this.writer_.releaseLock();
+      this.writer_ = undefined;
+    }
+    this.writable_ = undefined;
+
+    // Close the receiver asynchronously so the reply to this message can be
+    // sent first.
+    const receiver = this.receiver_;
+    this.receiver_ = undefined;
+    setTimeout(() => {
+      receiver.$.close();
+    }, 0);
+
+    return {};
+  }
+}
+
+// Implementation of blink.mojom.SerialService.
+class FakeSerialService {
+  constructor() {
+    this.interceptor_ =
+        new MojoInterfaceInterceptor(SerialService.$interfaceName);
+    this.interceptor_.oninterfacerequest = e => this.bind(e.handle);
+    this.receiver_ = new SerialServiceReceiver(this);
+    this.clients_ = [];
+    this.nextToken_ = 0;
+    this.reset();
+  }
+
+  start() {
+    this.interceptor_.start();
+  }
+
+  stop() {
+    this.interceptor_.stop();
+  }
+
+  reset() {
+    this.ports_ = new Map();
+    this.selectedPort_ = null;
+  }
+
+  addPort(info) {
+    let portInfo = {};
+    if (info?.usbVendorId !== undefined) {
+      portInfo.hasUsbVendorId = true;
+      portInfo.usbVendorId = info.usbVendorId;
+    }
+    if (info?.usbProductId !== undefined) {
+      portInfo.hasUsbProductId = true;
+      portInfo.usbProductId = info.usbProductId;
+    }
+
+    let token = ++this.nextToken_;
+    portInfo.token = {high: 0n, low: BigInt(token)};
+
+    let record = {
+      portInfo: portInfo,
+      fakePort: new FakeSerialPort(),
+    };
+    this.ports_.set(token, record);
+
+    for (let client of this.clients_) {
+      client.onPortAdded(portInfo);
+    }
+
+    return token;
+  }
+
+  removePort(token) {
+    let record = this.ports_.get(token);
+    if (record === undefined) {
+      return;
+    }
+
+    this.ports_.delete(token);
+
+    for (let client of this.clients_) {
+      client.onPortRemoved(record.portInfo);
+    }
+  }
+
+  setSelectedPort(token) {
+    this.selectedPort_ = this.ports_.get(token);
+  }
+
+  getFakePort(token) {
+    let record = this.ports_.get(token);
+    if (record === undefined)
+      return undefined;
+    return record.fakePort;
+  }
+
+  bind(handle) {
+    this.receiver_.$.bindHandle(handle);
+  }
+
+  async setClient(client_remote) {
+    this.clients_.push(client_remote);
+  }
+
+  async getPorts() {
+    return {
+      ports: Array.from(this.ports_, ([token, record]) => record.portInfo)
+    };
+  }
+
+  async requestPort(filters) {
+    if (this.selectedPort_)
+      return { port: this.selectedPort_.portInfo };
+    else
+      return { port: null };
+  }
+
+  async openPort(token, options, client) {
+    let record = this.ports_.get(Number(token.low));
+    if (record !== undefined) {
+      return {port: record.fakePort.open(options, client)};
+    } else {
+      return {port: null};
+    }
+  }
+
+  async forgetPort(token) {
+    let record = this.ports_.get(Number(token.low));
+    if (record === undefined) {
+      return {success: false};
+    }
+
+    this.ports_.delete(Number(token.low));
+    if (record.fakePort.receiver_) {
+      record.fakePort.receiver_.$.close();
+      record.fakePort.receiver_ = undefined;
+    }
+    return {success: true};
+  }
+}
+
+export const fakeSerialService = new FakeSerialService();
diff --git a/test/wpt/tests/resources/chromium/generic_sensor_mocks.js b/test/wpt/tests/resources/chromium/generic_sensor_mocks.js
new file mode 100644
index 0000000..98a29c2
--- /dev/null
+++ b/test/wpt/tests/resources/chromium/generic_sensor_mocks.js
@@ -0,0 +1,519 @@
+import {ReportingMode, Sensor, SensorClientRemote, SensorReceiver, SensorRemote, SensorType} from '/gen/services/device/public/mojom/sensor.mojom.m.js';
+import {SensorCreationResult, SensorInitParams_READ_BUFFER_SIZE_FOR_TESTS, SensorProvider, SensorProviderReceiver} from '/gen/services/device/public/mojom/sensor_provider.mojom.m.js';
+
+// A "sliding window" that iterates over |data| and returns one item at a
+// time, advancing and wrapping around as needed. |data| must be an array of
+// arrays.
+self.RingBuffer = class {
+  constructor(data) {
+    this.bufferPosition_ = 0;
+    // Validate |data|'s format and deep-copy every element.
+    this.data_ = Array.from(data, element => {
+      if (!Array.isArray(element)) {
+        throw new TypeError('Every |data| element must be an array.');
+      }
+      return Array.from(element);
+    })
+  }
+
+  next() {
+    const value = this.data_[this.bufferPosition_];
+    this.bufferPosition_ = (this.bufferPosition_ + 1) % this.data_.length;
+    return { done: false, value: value };
+  }
+
+  value() {
+    return this.data_[this.bufferPosition_];
+  }
+
+  [Symbol.iterator]() {
+    return this;
+  }
+};
+
+class DefaultSensorTraits {
+  // https://w3c.github.io/sensors/#threshold-check-algorithm
+  static isSignificantlyDifferent(reading1, reading2) {
+    return true;
+  }
+
+  // https://w3c.github.io/sensors/#reading-quantization-algorithm
+  static roundToMultiple(reading) {
+    return reading;
+  }
+
+  // https://w3c.github.io/ambient-light/#ambient-light-threshold-check-algorithm
+  static areReadingsEqual(reading1, reading2) {
+    return false;
+  }
+}
+
+class AmbientLightSensorTraits extends DefaultSensorTraits {
+  // https://w3c.github.io/ambient-light/#reduce-sensor-accuracy
+  static #ROUNDING_MULTIPLE = 50;
+  static #SIGNIFICANCE_THRESHOLD = 25;
+
+  // https://w3c.github.io/ambient-light/#ambient-light-threshold-check-algorithm
+  static isSignificantlyDifferent([illuminance1], [illuminance2]) {
+    return Math.abs(illuminance1 - illuminance2) >=
+        this.#SIGNIFICANCE_THRESHOLD;
+  }
+
+  // https://w3c.github.io/ambient-light/#ambient-light-reading-quantization-algorithm
+  static roundToMultiple(reading) {
+    const illuminance = reading[0];
+    const scaledValue =
+        illuminance / AmbientLightSensorTraits.#ROUNDING_MULTIPLE;
+    let roundedReading = reading.splice();
+
+    if (illuminance < 0.0) {
+      roundedReading[0] = -AmbientLightSensorTraits.#ROUNDING_MULTIPLE *
+          Math.floor(-scaledValue + 0.5);
+    } else {
+      roundedReading[0] = AmbientLightSensorTraits.#ROUNDING_MULTIPLE *
+          Math.floor(scaledValue + 0.5);
+    }
+
+    return roundedReading;
+  }
+
+  // https://w3c.github.io/ambient-light/#ambient-light-threshold-check-algorithm
+  static areReadingsEqual([illuminance1], [illuminance2]) {
+    return illuminance1 === illuminance2;
+  }
+}
+
+self.GenericSensorTest = (() => {
+  // Default sensor frequency in default configurations.
+  const DEFAULT_FREQUENCY = 5;
+
+  // Class that mocks Sensor interface defined in
+  // https://cs.chromium.org/chromium/src/services/device/public/mojom/sensor.mojom
+  class MockSensor {
+    static #BUFFER_OFFSET_TIMESTAMP = 1;
+    static #BUFFER_OFFSET_READINGS = 2;
+
+    constructor(sensorRequest, buffer, reportingMode, sensorType) {
+      this.client_ = null;
+      this.startShouldFail_ = false;
+      this.notifyOnReadingChange_ = true;
+      this.reportingMode_ = reportingMode;
+      this.sensorType_ = sensorType;
+      this.sensorReadingTimerId_ = null;
+      this.readingData_ = null;
+      this.requestedFrequencies_ = [];
+      // The Blink implementation (third_party/blink/renderer/modules/sensor/sensor.cc)
+      // sets a timestamp by creating a DOMHighResTimeStamp from a given platform timestamp.
+      // In this mock implementation we use a starting value
+      // and an increment step value that resemble a platform timestamp reasonably enough.
+      this.timestamp_ = window.performance.timeOrigin;
+      // |buffer| represents a SensorReadingSharedBuffer on the C++ side in
+      // Chromium. It consists, in this order, of a
+      // SensorReadingField<OneWriterSeqLock> (an 8-byte union that includes
+      // 32-bit integer used by the lock class), and a SensorReading consisting
+      // of an 8-byte timestamp and 4 8-byte reading fields.
+      //
+      // |this.buffer_[0]| is zeroed by default, which allows OneWriterSeqLock
+      // to work with our custom memory buffer that did not actually create a
+      // OneWriterSeqLock instance. It is never changed manually here.
+      //
+      // Use MockSensor.#BUFFER_OFFSET_TIMESTAMP and
+      // MockSensor.#BUFFER_OFFSET_READINGS to access the other positions in
+      // |this.buffer_| without having to hardcode magic numbers in the code.
+      this.buffer_ = buffer;
+      this.buffer_.fill(0);
+      this.receiver_ = new SensorReceiver(this);
+      this.receiver_.$.bindHandle(sensorRequest.handle);
+      this.lastRawReading_ = null;
+      this.lastRoundedReading_ = null;
+
+      if (sensorType == SensorType.AMBIENT_LIGHT) {
+        this.sensorTraits = AmbientLightSensorTraits;
+      } else {
+        this.sensorTraits = DefaultSensorTraits;
+      }
+    }
+
+    // Returns default configuration.
+    async getDefaultConfiguration() {
+      return { frequency: DEFAULT_FREQUENCY };
+    }
+
+    // Adds configuration for the sensor and starts reporting fake data
+    // through setSensorReading function.
+    async addConfiguration(configuration) {
+      this.requestedFrequencies_.push(configuration.frequency);
+      // Sort using descending order.
+      this.requestedFrequencies_.sort(
+          (first, second) => { return second - first });
+
+      if (!this.startShouldFail_ )
+        this.startReading();
+
+      return { success: !this.startShouldFail_ };
+    }
+
+    // Removes sensor configuration from the list of active configurations and
+    // stops notification about sensor reading changes if
+    // requestedFrequencies_ is empty.
+    removeConfiguration(configuration) {
+      const index = this.requestedFrequencies_.indexOf(configuration.frequency);
+      if (index == -1)
+        return;
+
+      this.requestedFrequencies_.splice(index, 1);
+      if (this.requestedFrequencies_.length === 0)
+        this.stopReading();
+    }
+
+    // ConfigureReadingChangeNotifications(bool enabled)
+    // Configures whether to report a reading change when in ON_CHANGE
+    // reporting mode.
+    configureReadingChangeNotifications(notifyOnReadingChange) {
+      this.notifyOnReadingChange_ = notifyOnReadingChange;
+    }
+
+    resume() {
+      this.startReading();
+    }
+
+    suspend() {
+      this.stopReading();
+    }
+
+    // Mock functions
+
+    // Resets mock Sensor state.
+    reset() {
+      this.stopReading();
+      this.startShouldFail_ = false;
+      this.requestedFrequencies_ = [];
+      this.notifyOnReadingChange_ = true;
+      this.readingData_ = null;
+      this.buffer_.fill(0);
+      this.receiver_.$.close();
+      this.lastRawReading_ = null;
+      this.lastRoundedReading_ = null;
+    }
+
+    // Sets fake data that is used to deliver sensor reading updates.
+    setSensorReading(readingData) {
+      this.readingData_ = new RingBuffer(readingData);
+    }
+
+    // This is a workaround to accommodate Blink's Device Orientation
+    // implementation. In general, all tests should use setSensorReading()
+    // instead.
+    setSensorReadingImmediately(readingData) {
+      this.setSensorReading(readingData);
+
+      const reading = this.readingData_.value();
+      this.buffer_.set(reading, MockSensor.#BUFFER_OFFSET_READINGS);
+      this.buffer_[MockSensor.#BUFFER_OFFSET_TIMESTAMP] = this.timestamp_++;
+    }
+
+    // Sets flag that forces sensor to fail when addConfiguration is invoked.
+    setStartShouldFail(shouldFail) {
+      this.startShouldFail_ = shouldFail;
+    }
+
+    startReading() {
+      if (this.readingData_ != null) {
+        this.stopReading();
+      }
+      let maxFrequencyUsed = this.requestedFrequencies_[0];
+      let timeout = (1 / maxFrequencyUsed) * 1000;
+      this.sensorReadingTimerId_ = window.setInterval(() => {
+        if (this.readingData_) {
+          // |buffer_| is a TypedArray, so we need to make sure pass an
+          // array to set().
+          const reading = this.readingData_.next().value;
+          if (!Array.isArray(reading)) {
+            throw new TypeError("startReading(): The readings passed to " +
+              "setSensorReading() must be arrays");
+          }
+
+          if (this.reportingMode_ == ReportingMode.ON_CHANGE &&
+              this.lastRawReading_ !== null &&
+              !this.sensorTraits.isSignificantlyDifferent(
+                  this.lastRawReading_, reading)) {
+            // In case new value is not significantly different compared to
+            // old value, new value is not sent.
+            return;
+          }
+
+          this.lastRawReading_ = reading.slice();
+          const roundedReading = this.sensorTraits.roundToMultiple(reading);
+
+          if (this.reportingMode_ == ReportingMode.ON_CHANGE &&
+              this.lastRoundedReading_ !== null &&
+              this.sensorTraits.areReadingsEqual(
+                roundedReading, this.lastRoundedReading_)) {
+            // In case new rounded value is not different compared to old
+            // value, new value is not sent.
+            return;
+          }
+          this.buffer_.set(roundedReading, MockSensor.#BUFFER_OFFSET_READINGS);
+          this.lastRoundedReading_ = roundedReading;
+        }
+
+        // For all tests sensor reading should have monotonically
+        // increasing timestamp.
+        this.buffer_[MockSensor.#BUFFER_OFFSET_TIMESTAMP] = this.timestamp_++;
+
+        if (this.reportingMode_ === ReportingMode.ON_CHANGE &&
+            this.notifyOnReadingChange_) {
+          this.client_.sensorReadingChanged();
+        }
+      }, timeout);
+    }
+
+    stopReading() {
+      if (this.sensorReadingTimerId_ != null) {
+        window.clearInterval(this.sensorReadingTimerId_);
+        this.sensorReadingTimerId_ = null;
+      }
+    }
+
+    getSamplingFrequency() {
+      if (this.requestedFrequencies_.length == 0) {
+        throw new Error("getSamplingFrequency(): No configured frequency");
+      }
+       return this.requestedFrequencies_[0];
+    }
+
+    isReadingData() {
+      return this.sensorReadingTimerId_ != null;
+    }
+  }
+
+  // Class that mocks SensorProvider interface defined in
+  // https://cs.chromium.org/chromium/src/services/device/public/mojom/sensor_provider.mojom
+  class MockSensorProvider {
+    constructor() {
+      this.readingSizeInBytes_ =
+          Number(SensorInitParams_READ_BUFFER_SIZE_FOR_TESTS);
+      this.sharedBufferSizeInBytes_ =
+          this.readingSizeInBytes_ * (SensorType.MAX_VALUE + 1);
+      let rv = Mojo.createSharedBuffer(this.sharedBufferSizeInBytes_);
+      if (rv.result != Mojo.RESULT_OK) {
+        throw new Error('MockSensorProvider: Failed to create shared buffer');
+      }
+      const handle = rv.handle;
+      rv = handle.mapBuffer(0, this.sharedBufferSizeInBytes_);
+      if (rv.result != Mojo.RESULT_OK) {
+        throw new Error("MockSensorProvider: Failed to map shared buffer");
+      }
+      this.shmemArrayBuffer_ = rv.buffer;
+      rv = handle.duplicateBufferHandle({readOnly: true});
+      if (rv.result != Mojo.RESULT_OK) {
+        throw new Error(
+            'MockSensorProvider: failed to duplicate shared buffer');
+      }
+      this.readOnlySharedBufferHandle_ = rv.handle;
+      this.activeSensors_ = new Map();
+      this.resolveFuncs_ = new Map();
+      this.getSensorShouldFail_ = new Map();
+      this.permissionsDenied_ = new Map();
+      this.maxFrequency_ = 60;
+      this.minFrequency_ = 1;
+      this.mojomSensorType_ = new Map([
+        ['Accelerometer', SensorType.ACCELEROMETER],
+        ['LinearAccelerationSensor', SensorType.LINEAR_ACCELERATION],
+        ['GravitySensor', SensorType.GRAVITY],
+        ['AmbientLightSensor', SensorType.AMBIENT_LIGHT],
+        ['Gyroscope', SensorType.GYROSCOPE],
+        ['Magnetometer', SensorType.MAGNETOMETER],
+        ['AbsoluteOrientationSensor',
+            SensorType.ABSOLUTE_ORIENTATION_QUATERNION],
+        ['AbsoluteOrientationEulerAngles',
+            SensorType.ABSOLUTE_ORIENTATION_EULER_ANGLES],
+        ['RelativeOrientationSensor',
+            SensorType.RELATIVE_ORIENTATION_QUATERNION],
+        ['RelativeOrientationEulerAngles',
+            SensorType.RELATIVE_ORIENTATION_EULER_ANGLES],
+        ['ProximitySensor', SensorType.PROXIMITY]
+      ]);
+      this.receiver_ = new SensorProviderReceiver(this);
+
+      this.interceptor_ =
+          new MojoInterfaceInterceptor(SensorProvider.$interfaceName);
+      this.interceptor_.oninterfacerequest = e => {
+        this.bindToPipe(e.handle);
+      };
+      this.interceptor_.start();
+    }
+
+    // Returns initialized Sensor proxy to the client.
+    async getSensor(type) {
+      if (this.getSensorShouldFail_.get(type)) {
+        return {result: SensorCreationResult.ERROR_NOT_AVAILABLE,
+                initParams: null};
+      }
+      if (this.permissionsDenied_.get(type)) {
+        return {result: SensorCreationResult.ERROR_NOT_ALLOWED,
+                initParams: null};
+      }
+
+      const offset = type * this.readingSizeInBytes_;
+      const reportingMode = ReportingMode.ON_CHANGE;
+
+      const sensor = new SensorRemote();
+      if (!this.activeSensors_.has(type)) {
+        const shmemView = new Float64Array(
+            this.shmemArrayBuffer_, offset,
+            this.readingSizeInBytes_ / Float64Array.BYTES_PER_ELEMENT);
+        const mockSensor = new MockSensor(
+            sensor.$.bindNewPipeAndPassReceiver(), shmemView, reportingMode,
+            type);
+        this.activeSensors_.set(type, mockSensor);
+        this.activeSensors_.get(type).client_ = new SensorClientRemote();
+      }
+
+      const rv = this.readOnlySharedBufferHandle_.duplicateBufferHandle(
+          {readOnly: true});
+      if (rv.result != Mojo.RESULT_OK) {
+        throw new Error('getSensor(): failed to duplicate shared buffer');
+      }
+
+      const defaultConfig = { frequency: DEFAULT_FREQUENCY };
+      // Consider sensor traits to meet assertions in C++ code (see
+      // services/device/public/cpp/generic_sensor/sensor_traits.h)
+      if (type == SensorType.AMBIENT_LIGHT || type == SensorType.MAGNETOMETER) {
+        this.maxFrequency_ = Math.min(10, this.maxFrequency_);
+      }
+
+      const client = this.activeSensors_.get(type).client_;
+      const initParams = {
+        sensor,
+        clientReceiver: client.$.bindNewPipeAndPassReceiver(),
+        memory: {buffer: rv.handle},
+        bufferOffset: BigInt(offset),
+        mode: reportingMode,
+        defaultConfiguration: defaultConfig,
+        minimumFrequency: this.minFrequency_,
+        maximumFrequency: this.maxFrequency_
+      };
+
+      if (this.resolveFuncs_.has(type)) {
+        for (let resolveFunc of this.resolveFuncs_.get(type)) {
+          resolveFunc(this.activeSensors_.get(type));
+        }
+        this.resolveFuncs_.delete(type);
+      }
+
+      return {result: SensorCreationResult.SUCCESS, initParams};
+    }
+
+    // Binds object to mojo message pipe
+    bindToPipe(pipe) {
+      this.receiver_.$.bindHandle(pipe);
+    }
+
+    // Mock functions
+
+    // Resets state of mock SensorProvider between test runs.
+    reset() {
+      for (const sensor of this.activeSensors_.values()) {
+        sensor.reset();
+      }
+      this.activeSensors_.clear();
+      this.resolveFuncs_.clear();
+      this.getSensorShouldFail_.clear();
+      this.permissionsDenied_.clear();
+      this.maxFrequency_ = 60;
+      this.minFrequency_ = 1;
+      this.receiver_.$.close();
+      this.interceptor_.stop();
+    }
+
+    // Sets flag that forces mock SensorProvider to fail when getSensor() is
+    // invoked.
+    setGetSensorShouldFail(sensorType, shouldFail) {
+      this.getSensorShouldFail_.set(this.mojomSensorType_.get(sensorType),
+          shouldFail);
+    }
+
+    setPermissionsDenied(sensorType, permissionsDenied) {
+      this.permissionsDenied_.set(this.mojomSensorType_.get(sensorType),
+          permissionsDenied);
+    }
+
+    // Returns mock sensor that was created in getSensor to the layout test.
+    getCreatedSensor(sensorType) {
+      const type = this.mojomSensorType_.get(sensorType);
+      if (typeof type != "number") {
+        throw new TypeError(`getCreatedSensor(): Invalid sensor type ${sensorType}`);
+      }
+
+      if (this.activeSensors_.has(type)) {
+        return Promise.resolve(this.activeSensors_.get(type));
+      }
+
+      return new Promise(resolve => {
+        if (!this.resolveFuncs_.has(type)) {
+          this.resolveFuncs_.set(type, []);
+        }
+        this.resolveFuncs_.get(type).push(resolve);
+      });
+    }
+
+    // Sets the maximum frequency for a concrete sensor.
+    setMaximumSupportedFrequency(frequency) {
+      this.maxFrequency_ = frequency;
+    }
+
+    // Sets the minimum frequency for a concrete sensor.
+    setMinimumSupportedFrequency(frequency) {
+      this.minFrequency_ = frequency;
+    }
+  }
+
+  let testInternal = {
+    initialized: false,
+    sensorProvider: null
+  }
+
+  class GenericSensorTestChromium {
+    constructor() {
+      Object.freeze(this); // Make it immutable.
+    }
+
+    async initialize() {
+      if (testInternal.initialized)
+        throw new Error('Call reset() before initialize().');
+
+      // Grant sensor permissions for Chromium testdriver.
+      // testdriver.js only works in the top-level browsing context, so do
+      // nothing if we're in e.g. an iframe.
+      if (window.parent === window) {
+        for (const entry
+                 of ['accelerometer', 'gyroscope', 'magnetometer',
+                     'ambient-light-sensor']) {
+          await test_driver.set_permission({name: entry}, 'granted');
+        }
+      }
+
+      testInternal.sensorProvider = new MockSensorProvider;
+      testInternal.initialized = true;
+    }
+    // Resets state of sensor mocks between test runs.
+    async reset() {
+      if (!testInternal.initialized)
+        throw new Error('Call initialize() before reset().');
+      testInternal.sensorProvider.reset();
+      testInternal.sensorProvider = null;
+      testInternal.initialized = false;
+
+      // Wait for an event loop iteration to let any pending mojo commands in
+      // the sensor provider finish.
+      await new Promise(resolve => setTimeout(resolve, 0));
+    }
+
+    getSensorProvider() {
+      return testInternal.sensorProvider;
+    }
+  }
+
+  return GenericSensorTestChromium;
+})();
diff --git a/test/wpt/tests/resources/chromium/generic_sensor_mocks.js.headers b/test/wpt/tests/resources/chromium/generic_sensor_mocks.js.headers
new file mode 100644
index 0000000..6805c32
--- /dev/null
+++ b/test/wpt/tests/resources/chromium/generic_sensor_mocks.js.headers
@@ -0,0 +1 @@
+Content-Type: text/javascript; charset=utf-8
diff --git a/test/wpt/tests/resources/chromium/mock-barcodedetection.js b/test/wpt/tests/resources/chromium/mock-barcodedetection.js
new file mode 100644
index 0000000..b0d2e0a
--- /dev/null
+++ b/test/wpt/tests/resources/chromium/mock-barcodedetection.js
@@ -0,0 +1,136 @@
+import {BarcodeDetectionReceiver, BarcodeFormat} from '/gen/services/shape_detection/public/mojom/barcodedetection.mojom.m.js';
+import {BarcodeDetectionProvider, BarcodeDetectionProviderReceiver} from '/gen/services/shape_detection/public/mojom/barcodedetection_provider.mojom.m.js';
+
+self.BarcodeDetectionTest = (() => {
+  // Class that mocks BarcodeDetectionProvider interface defined in
+  // https://cs.chromium.org/chromium/src/services/shape_detection/public/mojom/barcodedetection_provider.mojom
+  class MockBarcodeDetectionProvider {
+    constructor() {
+      this.receiver_ = new BarcodeDetectionProviderReceiver(this);
+
+      this.interceptor_ = new MojoInterfaceInterceptor(
+          BarcodeDetectionProvider.$interfaceName);
+      this.interceptor_.oninterfacerequest = e => {
+        if (this.should_close_pipe_on_request_)
+          e.handle.close();
+        else
+          this.receiver_.$.bindHandle(e.handle);
+      }
+      this.interceptor_.start();
+      this.should_close_pipe_on_request_ = false;
+    }
+
+    createBarcodeDetection(request, options) {
+      this.mockService_ = new MockBarcodeDetection(request, options);
+    }
+
+    enumerateSupportedFormats() {
+      return {
+        supportedFormats: [
+          BarcodeFormat.AZTEC,
+          BarcodeFormat.DATA_MATRIX,
+          BarcodeFormat.QR_CODE,
+        ]
+      };
+    }
+
+    getFrameData() {
+      return this.mockService_.bufferData_;
+    }
+
+    getFormats() {
+     return this.mockService_.options_.formats;
+    }
+
+    reset() {
+      this.mockService_ = null;
+      this.should_close_pipe_on_request_ = false;
+      this.receiver_.$.close();
+      this.interceptor_.stop();
+    }
+
+    // simulate a 'no implementation available' case
+    simulateNoImplementation() {
+      this.should_close_pipe_on_request_ = true;
+    }
+  }
+
+  // Class that mocks BarcodeDetection interface defined in
+  // https://cs.chromium.org/chromium/src/services/shape_detection/public/mojom/barcodedetection.mojom
+  class MockBarcodeDetection {
+    constructor(request, options) {
+      this.options_ = options;
+      this.receiver_ = new BarcodeDetectionReceiver(this);
+      this.receiver_.$.bindHandle(request.handle);
+    }
+
+    detect(bitmapData) {
+      this.bufferData_ =
+          new Uint32Array(getArrayBufferFromBigBuffer(bitmapData.pixelData));
+      return {
+        results: [
+          {
+            rawValue : "cats",
+            boundingBox: { x: 1.0, y: 1.0, width: 100.0, height: 100.0 },
+            format: BarcodeFormat.QR_CODE,
+            cornerPoints: [
+              { x: 1.0, y: 1.0 },
+              { x: 101.0, y: 1.0 },
+              { x: 101.0, y: 101.0 },
+              { x: 1.0, y: 101.0 }
+            ],
+          },
+          {
+            rawValue : "dogs",
+            boundingBox: { x: 2.0, y: 2.0, width: 50.0, height: 50.0 },
+            format: BarcodeFormat.CODE_128,
+            cornerPoints: [
+              { x: 2.0, y: 2.0 },
+              { x: 52.0, y: 2.0 },
+              { x: 52.0, y: 52.0 },
+              { x: 2.0, y: 52.0 }
+            ],
+          },
+        ],
+      };
+    }
+  }
+
+  let testInternal = {
+    initialized: false,
+    MockBarcodeDetectionProvider: null
+  }
+
+  class BarcodeDetectionTestChromium {
+    constructor() {
+      Object.freeze(this); // Make it immutable.
+    }
+
+    initialize() {
+      if (testInternal.initialized)
+        throw new Error('Call reset() before initialize().');
+
+      testInternal.MockBarcodeDetectionProvider = new MockBarcodeDetectionProvider;
+      testInternal.initialized = true;
+    }
+
+    // Resets state of barcode detection mocks between test runs.
+    async reset() {
+      if (!testInternal.initialized)
+        throw new Error('Call initialize() before reset().');
+      testInternal.MockBarcodeDetectionProvider.reset();
+      testInternal.MockBarcodeDetectionProvider = null;
+      testInternal.initialized = false;
+
+      await new Promise(resolve => setTimeout(resolve, 0));
+    }
+
+    MockBarcodeDetectionProvider() {
+      return testInternal.MockBarcodeDetectionProvider;
+    }
+  }
+
+  return BarcodeDetectionTestChromium;
+})();
+
+self.BarcodeFormat = BarcodeFormat;
diff --git a/test/wpt/tests/resources/chromium/mock-barcodedetection.js.headers b/test/wpt/tests/resources/chromium/mock-barcodedetection.js.headers
new file mode 100644
index 0000000..6c61a34
--- /dev/null
+++ b/test/wpt/tests/resources/chromium/mock-barcodedetection.js.headers
@@ -0,0 +1 @@
+Content-Type: text/javascript; charset=utf-8
\ No newline at end of file
diff --git a/test/wpt/tests/resources/chromium/mock-battery-monitor.headers b/test/wpt/tests/resources/chromium/mock-battery-monitor.headers
new file mode 100644
index 0000000..6805c32
--- /dev/null
+++ b/test/wpt/tests/resources/chromium/mock-battery-monitor.headers
@@ -0,0 +1 @@
+Content-Type: text/javascript; charset=utf-8
diff --git a/test/wpt/tests/resources/chromium/mock-battery-monitor.js b/test/wpt/tests/resources/chromium/mock-battery-monitor.js
new file mode 100644
index 0000000..8fa27bc
--- /dev/null
+++ b/test/wpt/tests/resources/chromium/mock-battery-monitor.js
@@ -0,0 +1,61 @@
+import {BatteryMonitor, BatteryMonitorReceiver} from '/gen/services/device/public/mojom/battery_monitor.mojom.m.js';
+
+class MockBatteryMonitor {
+  constructor() {
+    this.receiver_ = new BatteryMonitorReceiver(this);
+    this.interceptor_ =
+        new MojoInterfaceInterceptor(BatteryMonitor.$interfaceName);
+    this.interceptor_.oninterfacerequest = e =>
+        this.receiver_.$.bindHandle(e.handle);
+    this.reset();
+  }
+
+  start() {
+    this.interceptor_.start();
+  }
+
+  stop() {
+    this.interceptor_.stop();
+  }
+
+  reset() {
+    this.pendingRequests_ = [];
+    this.status_ = null;
+    this.lastKnownStatus_ = null;
+  }
+
+  queryNextStatus() {
+    const result = new Promise(resolve => this.pendingRequests_.push(resolve));
+    this.runCallbacks_();
+    return result;
+  }
+
+  setBatteryStatus(charging, chargingTime, dischargingTime, level) {
+    this.status_ = {charging, chargingTime, dischargingTime, level};
+    this.lastKnownStatus_ = this.status_;
+    this.runCallbacks_();
+  }
+
+  verifyBatteryStatus(manager) {
+    assert_not_equals(manager, undefined);
+    assert_not_equals(this.lastKnownStatus_, null);
+    assert_equals(manager.charging, this.lastKnownStatus_.charging);
+    assert_equals(manager.chargingTime, this.lastKnownStatus_.chargingTime);
+    assert_equals(
+        manager.dischargingTime, this.lastKnownStatus_.dischargingTime);
+    assert_equals(manager.level, this.lastKnownStatus_.level);
+  }
+
+  runCallbacks_() {
+    if (!this.status_ || !this.pendingRequests_.length)
+      return;
+
+    let result = {status: this.status_};
+    while (this.pendingRequests_.length) {
+      this.pendingRequests_.pop()(result);
+    }
+    this.status_ = null;
+  }
+}
+
+export const mockBatteryMonitor = new MockBatteryMonitor();
diff --git a/test/wpt/tests/resources/chromium/mock-direct-sockets.js b/test/wpt/tests/resources/chromium/mock-direct-sockets.js
new file mode 100644
index 0000000..6d557f7
--- /dev/null
+++ b/test/wpt/tests/resources/chromium/mock-direct-sockets.js
@@ -0,0 +1,94 @@
+'use strict';
+
+import {DirectSocketsService, DirectSocketsServiceReceiver} from '/gen/third_party/blink/public/mojom/direct_sockets/direct_sockets.mojom.m.js';
+
+self.DirectSocketsServiceTest = (() => {
+  // Class that mocks DirectSocketsService interface defined in
+  // https://source.chromium.org/chromium/chromium/src/third_party/blink/public/mojom/direct_sockets/direct_sockets.mojom
+  class MockDirectSocketsService {
+    constructor() {
+      this.interceptor_ = new MojoInterfaceInterceptor(DirectSocketsService.$interfaceName);
+      this.receiver_ = new DirectSocketsServiceReceiver(this);
+      this.interceptor_.oninterfacerequest = e =>
+          this.receiver_.$.bindHandle(e.handle);
+      this.interceptor_.start();
+    }
+
+    reset() {
+      this.receiver_.$.close();
+      this.interceptor_.stop();
+    }
+
+    openTCPSocket(
+      options,
+      receiver,
+      observer) {
+      return Promise.resolve({
+        // return result = net:Error::NOT_IMPLEMENTED (code -11)
+        result: -11
+      });
+    }
+
+    openConnectedUDPSocket(
+      options,
+      receiver,
+      listener) {
+      return Promise.resolve({
+        // return result = net:Error::NOT_IMPLEMENTED (code -11)
+        result: -11
+      });
+    }
+
+    openBoundUDPSocket(
+      options,
+      receiver,
+      listener) {
+      return Promise.resolve({
+        // return result = net:Error::NOT_IMPLEMENTED (code -11)
+        result: -11
+      });
+    }
+
+    openTCPServerSocket(
+      options,
+      receiver) {
+      return Promise.resolve({
+        // return result = net:Error::NOT_IMPLEMENTED (code -11)
+        result: -11
+      });
+    }
+  }
+
+  let testInternal = {
+    initialized: false,
+    mockDirectSocketsService: null
+  }
+
+  class DirectSocketsServiceTestChromium {
+    constructor() {
+      Object.freeze(this);  // Make it immutable.
+    }
+
+    initialize() {
+      if (!testInternal.initialized) {
+        testInternal = {
+          mockDirectSocketsService: new MockDirectSocketsService(),
+          initialized: true
+        };
+      }
+    }
+
+    async reset() {
+      if (testInternal.initialized) {
+        testInternal.mockDirectSocketsService.reset();
+        testInternal = {
+          mockDirectSocketsService: null,
+          initialized: false
+        };
+        await new Promise(resolve => setTimeout(resolve, 0));
+      }
+    }
+  }
+
+  return DirectSocketsServiceTestChromium;
+})();
diff --git a/test/wpt/tests/resources/chromium/mock-facedetection.js b/test/wpt/tests/resources/chromium/mock-facedetection.js
new file mode 100644
index 0000000..7ae6586
--- /dev/null
+++ b/test/wpt/tests/resources/chromium/mock-facedetection.js
@@ -0,0 +1,130 @@
+import {FaceDetectionReceiver, LandmarkType} from '/gen/services/shape_detection/public/mojom/facedetection.mojom.m.js';
+import {FaceDetectionProvider, FaceDetectionProviderReceiver} from '/gen/services/shape_detection/public/mojom/facedetection_provider.mojom.m.js';
+
+self.FaceDetectionTest = (() => {
+  // Class that mocks FaceDetectionProvider interface defined in
+  // https://cs.chromium.org/chromium/src/services/shape_detection/public/mojom/facedetection_provider.mojom
+  class MockFaceDetectionProvider {
+    constructor() {
+      this.receiver_ = new FaceDetectionProviderReceiver(this);
+
+      this.interceptor_ = new MojoInterfaceInterceptor(
+          FaceDetectionProvider.$interfaceName);
+      this.interceptor_.oninterfacerequest =
+         e => this.receiver_.$.bindHandle(e.handle);
+      this.interceptor_.start();
+    }
+
+    createFaceDetection(request, options) {
+      this.mockService_ = new MockFaceDetection(request, options);
+    }
+
+    getFrameData() {
+      return this.mockService_.bufferData_;
+    }
+
+    getMaxDetectedFaces() {
+     return this.mockService_.maxDetectedFaces_;
+    }
+
+    getFastMode () {
+      return this.mockService_.fastMode_;
+    }
+
+    reset() {
+      this.mockService_ = null;
+      this.receiver_.$.close();
+      this.interceptor_.stop();
+    }
+  }
+
+  // Class that mocks FaceDetection interface defined in
+  // https://cs.chromium.org/chromium/src/services/shape_detection/public/mojom/facedetection.mojom
+  class MockFaceDetection {
+    constructor(request, options) {
+      this.maxDetectedFaces_ = options.maxDetectedFaces;
+      this.fastMode_ = options.fastMode;
+      this.receiver_ = new FaceDetectionReceiver(this);
+      this.receiver_.$.bindHandle(request.handle);
+    }
+
+    detect(bitmapData) {
+      this.bufferData_ =
+          new Uint32Array(getArrayBufferFromBigBuffer(bitmapData.pixelData));
+      return Promise.resolve({
+        results: [
+          {
+            boundingBox: {x: 1.0, y: 1.0, width: 100.0, height: 100.0},
+            landmarks: [{
+              type: LandmarkType.EYE,
+              locations: [{x: 4.0, y: 5.0}]
+            },
+            {
+              type: LandmarkType.EYE,
+              locations: [
+                {x: 4.0, y: 5.0}, {x: 5.0, y: 4.0}, {x: 6.0, y: 3.0},
+                {x: 7.0, y: 4.0}, {x: 8.0, y: 5.0}, {x: 7.0, y: 6.0},
+                {x: 6.0, y: 7.0}, {x: 5.0, y: 6.0}
+              ]
+            }]
+          },
+          {
+            boundingBox: {x: 2.0, y: 2.0, width: 200.0, height: 200.0},
+            landmarks: [{
+              type: LandmarkType.NOSE,
+              locations: [{x: 100.0, y: 50.0}]
+            },
+            {
+              type: LandmarkType.NOSE,
+              locations: [
+                {x: 80.0, y: 50.0}, {x: 70.0, y: 60.0}, {x: 60.0, y: 70.0},
+                {x: 70.0, y: 60.0}, {x: 80.0, y: 70.0}, {x: 90.0, y: 80.0},
+                {x: 100.0, y: 70.0}, {x: 90.0, y: 60.0}, {x: 80.0, y: 50.0}
+              ]
+            }]
+          },
+          {
+            boundingBox: {x: 3.0, y: 3.0, width: 300.0, height: 300.0},
+            landmarks: []
+          },
+        ]
+      });
+    }
+  }
+
+  let testInternal = {
+    initialized: false,
+    MockFaceDetectionProvider: null
+  }
+
+  class FaceDetectionTestChromium {
+    constructor() {
+      Object.freeze(this); // Make it immutable.
+    }
+
+    initialize() {
+      if (testInternal.initialized)
+        throw new Error('Call reset() before initialize().');
+
+      testInternal.MockFaceDetectionProvider = new MockFaceDetectionProvider;
+      testInternal.initialized = true;
+    }
+
+    // Resets state of face detection mocks between test runs.
+    async reset() {
+      if (!testInternal.initialized)
+        throw new Error('Call initialize() before reset().');
+      testInternal.MockFaceDetectionProvider.reset();
+      testInternal.MockFaceDetectionProvider = null;
+      testInternal.initialized = false;
+
+      await new Promise(resolve => setTimeout(resolve, 0));
+    }
+
+    MockFaceDetectionProvider() {
+      return testInternal.MockFaceDetectionProvider;
+    }
+  }
+
+  return FaceDetectionTestChromium;
+})();
diff --git a/test/wpt/tests/resources/chromium/mock-facedetection.js.headers b/test/wpt/tests/resources/chromium/mock-facedetection.js.headers
new file mode 100644
index 0000000..6c61a34
--- /dev/null
+++ b/test/wpt/tests/resources/chromium/mock-facedetection.js.headers
@@ -0,0 +1 @@
+Content-Type: text/javascript; charset=utf-8
\ No newline at end of file
diff --git a/test/wpt/tests/resources/chromium/mock-idle-detection.js b/test/wpt/tests/resources/chromium/mock-idle-detection.js
new file mode 100644
index 0000000..54fe5dd
--- /dev/null
+++ b/test/wpt/tests/resources/chromium/mock-idle-detection.js
@@ -0,0 +1,80 @@
+import {IdleManager, IdleManagerError, IdleManagerReceiver} from '/gen/third_party/blink/public/mojom/idle/idle_manager.mojom.m.js';
+
+/**
+ * This is a testing framework that enables us to test the user idle detection
+ * by intercepting the connection between the renderer and the browser and
+ * exposing a mocking API for tests.
+ *
+ * Usage:
+ *
+ * 1) Include <script src="mock.js"></script> in your file.
+ * 2) Set expectations
+ *   expect(addMonitor).andReturn((threshold, monitorPtr, callback) => {
+ *     // mock behavior
+ *   })
+ * 3) Call navigator.idle.query()
+ *
+ * The mocking API is blink agnostic and is designed such that other engines
+ * could implement it too. Here are the symbols that are exposed to tests:
+ *
+ * - function addMonitor(): the main/only function that can be mocked.
+ * - function expect(): the main/only function that enables us to mock it.
+ * - function close(): disconnects the interceptor.
+ * - enum UserIdleState {IDLE, ACTIVE}: blink agnostic constants.
+ * - enum ScreenIdleState {LOCKED, UNLOCKED}: blink agnostic constants.
+ */
+
+class FakeIdleMonitor {
+  addMonitor(threshold, monitorPtr, callback) {
+    return this.handler.addMonitor(threshold, monitorPtr);
+  }
+  setHandler(handler) {
+    this.handler = handler;
+    return this;
+  }
+  setBinding(binding) {
+    this.binding = binding;
+    return this;
+  }
+  close() {
+    this.binding.$.close();
+  }
+}
+
+self.IdleDetectorError = {};
+
+self.addMonitor = function addMonitor(threshold, monitorPtr, callback) {
+  throw new Error("expected to be overriden by tests");
+}
+
+async function close() {
+  interceptor.close();
+}
+
+self.expect = function(call) {
+  return {
+    andReturn(callback) {
+      let handler = {};
+      handler[call.name] = callback;
+      interceptor.setHandler(handler);
+    }
+  };
+};
+
+function intercept() {
+  let result = new FakeIdleMonitor();
+
+  let binding = new IdleManagerReceiver(result);
+  let interceptor = new MojoInterfaceInterceptor(IdleManager.$interfaceName);
+  interceptor.oninterfacerequest = e => binding.$.bindHandle(e.handle);
+  interceptor.start();
+
+  self.IdleDetectorError.SUCCESS = IdleManagerError.kSuccess;
+  self.IdleDetectorError.PERMISSION_DISABLED =
+      IdleManagerError.kPermissionDisabled;
+
+  result.setBinding(binding);
+  return result;
+}
+
+const interceptor = intercept();
diff --git a/test/wpt/tests/resources/chromium/mock-imagecapture.js b/test/wpt/tests/resources/chromium/mock-imagecapture.js
new file mode 100644
index 0000000..8424e1e
--- /dev/null
+++ b/test/wpt/tests/resources/chromium/mock-imagecapture.js
@@ -0,0 +1,309 @@
+import {BackgroundBlurMode, FillLightMode, ImageCapture, ImageCaptureReceiver, MeteringMode, RedEyeReduction} from '/gen/media/capture/mojom/image_capture.mojom.m.js';
+
+self.ImageCaptureTest = (() => {
+  // Class that mocks ImageCapture interface defined in
+  // https://cs.chromium.org/chromium/src/media/capture/mojom/image_capture.mojom
+  class MockImageCapture {
+    constructor() {
+      this.interceptor_ =
+          new MojoInterfaceInterceptor(ImageCapture.$interfaceName);
+      this.interceptor_.oninterfacerequest =
+        e => this.receiver_.$.bindHandle(e.handle);
+      this.interceptor_.start();
+
+      this.state_ = {
+        state: {
+          supportedWhiteBalanceModes: [
+            MeteringMode.SINGLE_SHOT,
+            MeteringMode.CONTINUOUS
+          ],
+          currentWhiteBalanceMode: MeteringMode.CONTINUOUS,
+          supportedExposureModes: [
+            MeteringMode.MANUAL,
+            MeteringMode.SINGLE_SHOT,
+            MeteringMode.CONTINUOUS
+          ],
+          currentExposureMode: MeteringMode.MANUAL,
+          supportedFocusModes: [
+            MeteringMode.MANUAL,
+            MeteringMode.SINGLE_SHOT
+          ],
+          currentFocusMode: MeteringMode.MANUAL,
+          pointsOfInterest: [{
+            x: 0.4,
+            y: 0.6
+          }],
+
+          exposureCompensation: {
+            min: -200.0,
+            max: 200.0,
+            current: 33.0,
+            step: 33.0
+          },
+          exposureTime: {
+            min: 100.0,
+            max: 100000.0,
+            current: 1000.0,
+            step: 100.0
+          },
+          colorTemperature: {
+            min: 2500.0,
+            max: 6500.0,
+            current: 6000.0,
+            step: 1000.0
+          },
+          iso: {
+            min: 100.0,
+            max: 12000.0,
+            current: 400.0,
+            step: 1.0
+          },
+
+          brightness: {
+            min: 1.0,
+            max: 10.0,
+            current: 5.0,
+            step: 1.0
+          },
+          contrast: {
+            min: 2.0,
+            max: 9.0,
+            current: 5.0,
+            step: 1.0
+          },
+          saturation: {
+            min: 3.0,
+            max: 8.0,
+            current: 6.0,
+            step: 1.0
+          },
+          sharpness: {
+            min: 4.0,
+            max: 7.0,
+            current: 7.0,
+            step: 1.0
+          },
+
+          focusDistance: {
+            min: 1.0,
+            max: 10.0,
+            current: 3.0,
+            step: 1.0
+          },
+
+          pan: {
+            min: 0.0,
+            max: 10.0,
+            current: 5.0,
+            step: 2.0
+          },
+
+          tilt: {
+            min: 0.0,
+            max: 10.0,
+            current: 5.0,
+            step: 2.0
+          },
+
+          zoom: {
+            min: 0.0,
+            max: 10.0,
+            current: 5.0,
+            step: 5.0
+          },
+
+          supportsTorch: true,
+          torch: false,
+
+          redEyeReduction: RedEyeReduction.CONTROLLABLE,
+          height: {
+            min: 240.0,
+            max: 2448.0,
+            current: 240.0,
+            step: 2.0
+          },
+          width: {
+            min: 320.0,
+            max: 3264.0,
+            current: 320.0,
+            step: 3.0
+          },
+          fillLightMode: [FillLightMode.AUTO, FillLightMode.FLASH],
+
+          supportedBackgroundBlurModes: [
+              BackgroundBlurMode.OFF,
+              BackgroundBlurMode.BLUR
+          ],
+          backgroundBlurMode: BackgroundBlurMode.OFF,
+        }
+      };
+      this.panTiltZoomPermissionStatus_ = null;
+      this.settings_ = null;
+      this.receiver_ = new ImageCaptureReceiver(this);
+    }
+
+    reset() {
+      this.receiver_.$.close();
+      this.interceptor_.stop();
+    }
+
+    async getPhotoState(source_id) {
+      const shouldKeepPanTiltZoom = await this.isPanTiltZoomPermissionGranted();
+      if (shouldKeepPanTiltZoom)
+        return Promise.resolve(this.state_);
+
+      const newState = {...this.state_};
+      newState.state.pan = {};
+      newState.state.tilt = {};
+      newState.state.zoom = {};
+      return Promise.resolve(newState);
+    }
+
+    async setPhotoOptions(source_id, settings) {
+      const isAllowedToControlPanTiltZoom = await this.isPanTiltZoomPermissionGranted();
+      if (!isAllowedToControlPanTiltZoom &&
+          (settings.hasPan || settings.hasTilt || settings.hasZoom)) {
+        return Promise.resolve({ success: false });
+      }
+      this.settings_ = settings;
+      if (settings.hasIso)
+        this.state_.state.iso.current = settings.iso;
+      if (settings.hasHeight)
+        this.state_.state.height.current = settings.height;
+      if (settings.hasWidth)
+        this.state_.state.width.current = settings.width;
+      if (settings.hasPan)
+        this.state_.state.pan.current = settings.pan;
+      if (settings.hasTilt)
+        this.state_.state.tilt.current = settings.tilt;
+      if (settings.hasZoom)
+        this.state_.state.zoom.current = settings.zoom;
+      if (settings.hasFocusMode)
+        this.state_.state.currentFocusMode = settings.focusMode;
+      if (settings.hasFocusDistance)
+        this.state_.state.focusDistance.current = settings.focusDistance;
+
+      if (settings.pointsOfInterest.length > 0) {
+        this.state_.state.pointsOfInterest =
+          settings.pointsOfInterest;
+      }
+
+      if (settings.hasExposureMode)
+        this.state_.state.currentExposureMode = settings.exposureMode;
+
+      if (settings.hasExposureCompensation) {
+        this.state_.state.exposureCompensation.current =
+          settings.exposureCompensation;
+      }
+      if (settings.hasExposureTime) {
+        this.state_.state.exposureTime.current =
+          settings.exposureTime;
+      }
+      if (settings.hasWhiteBalanceMode) {
+        this.state_.state.currentWhiteBalanceMode =
+          settings.whiteBalanceMode;
+      }
+      if (settings.hasFillLightMode)
+        this.state_.state.fillLightMode = [settings.fillLightMode];
+      if (settings.hasRedEyeReduction)
+        this.state_.state.redEyeReduction = settings.redEyeReduction;
+      if (settings.hasColorTemperature) {
+        this.state_.state.colorTemperature.current =
+          settings.colorTemperature;
+      }
+      if (settings.hasBrightness)
+        this.state_.state.brightness.current = settings.brightness;
+      if (settings.hasContrast)
+        this.state_.state.contrast.current = settings.contrast;
+      if (settings.hasSaturation)
+        this.state_.state.saturation.current = settings.saturation;
+      if (settings.hasSharpness)
+        this.state_.state.sharpness.current = settings.sharpness;
+
+      if (settings.hasTorch)
+        this.state_.state.torch = settings.torch;
+
+      if (settings.hasBackgroundBlurMode)
+        this.state_.state.backgroundBlurMode = [settings.backgroundBlurMode];
+
+      return Promise.resolve({
+        success: true
+      });
+    }
+
+    takePhoto(source_id) {
+      return Promise.resolve({
+        blob: {
+          mimeType: 'image/cat',
+          data: new Array(2)
+        }
+      });
+    }
+
+    async isPanTiltZoomPermissionGranted() {
+      if (!this.panTiltZoomPermissionStatus_) {
+        this.panTiltZoomPermissionStatus_ = await navigator.permissions.query({
+          name: "camera",
+          panTiltZoom: true
+        });
+      }
+      return this.panTiltZoomPermissionStatus_.state == "granted";
+    }
+
+    state() {
+      return this.state_.state;
+    }
+
+    turnOffBackgroundBlurMode() {
+      this.state_.state.backgroundBlurMode = BackgroundBlurMode.OFF;
+    }
+    turnOnBackgroundBlurMode() {
+      this.state_.state.backgroundBlurMode = BackgroundBlurMode.BLUR;
+    }
+    turnOffSupportedBackgroundBlurModes() {
+      this.state_.state.supportedBackgroundBlurModes = [BackgroundBlurMode.OFF];
+    }
+    turnOnSupportedBackgroundBlurModes() {
+      this.state_.state.supportedBackgroundBlurModes = [BackgroundBlurMode.BLUR];
+    }
+
+    options() {
+      return this.settings_;
+    }
+  }
+
+  let testInternal = {
+    initialized: false,
+    mockImageCapture: null
+  }
+
+  class ImageCaptureTestChromium {
+
+    constructor() {
+      Object.freeze(this); // Make it immutable.
+    }
+
+    initialize() {
+      if (testInternal.initialized)
+        throw new Error('Call reset() before initialize().');
+
+      testInternal.mockImageCapture = new MockImageCapture;
+      testInternal.initialized = true;
+    }
+    // Resets state of image capture mocks between test runs.
+    async reset() {
+      if (!testInternal.initialized)
+        throw new Error('Call initialize() before reset().');
+      testInternal.mockImageCapture.reset();
+      testInternal.mockImageCapture = null;
+      testInternal.initialized = false;
+
+      await new Promise(resolve => setTimeout(resolve, 0));
+    }
+    mockImageCapture() {
+      return testInternal.mockImageCapture;
+    }
+  }
+
+  return ImageCaptureTestChromium;
+})();
diff --git a/test/wpt/tests/resources/chromium/mock-managed-config.js b/test/wpt/tests/resources/chromium/mock-managed-config.js
new file mode 100644
index 0000000..c9980e1
--- /dev/null
+++ b/test/wpt/tests/resources/chromium/mock-managed-config.js
@@ -0,0 +1,91 @@
+'use strict'
+
+import{ManagedConfigurationObserverRemote, ManagedConfigurationService, ManagedConfigurationServiceReceiver} from '/gen/third_party/blink/public/mojom/device/device.mojom.m.js';
+
+
+self.ManagedConfigTest = (() => {
+  // Class that mocks ManagedConfigurationService interface defined in
+  // https://source.chromium.org/chromium/chromium/src/third_party/blink/public/mojom/device/device.mojom
+  class MockManagedConfig {
+    constructor() {
+      this.receiver_ = new ManagedConfigurationServiceReceiver(this);
+      this.interceptor_ = new MojoInterfaceInterceptor(
+          ManagedConfigurationService.$interfaceName);
+      this.interceptor_.oninterfacerequest = e =>
+          this.receiver_.$.bindHandle(e.handle);
+      this.interceptor_.start();
+      this.subscription_ = null;
+      this.reset();
+    }
+
+    reset() {
+      this.configuration_ = null;
+      this.onObserverAdd_ = null;
+    }
+
+    async getManagedConfiguration(keys) {
+      if (this.configuration_ === null) {
+        return {};
+      }
+
+      return {
+        configurations: Object.keys(this.configuration_)
+                            .filter(key => keys.includes(key))
+                            .reduce(
+                                (obj, key) => {
+                                  obj[key] =
+                                      JSON.stringify(this.configuration_[key]);
+                                  return obj;
+                                },
+                                {})
+      };
+    }
+
+    subscribeToManagedConfiguration(remote) {
+      this.subscription_ = remote;
+      if (this.onObserverAdd_ !== null) {
+        this.onObserverAdd_();
+      }
+    }
+
+    setManagedConfig(value) {
+      this.configuration_ = value;
+      if (this.subscription_ !== null) {
+        this.subscription_.onConfigurationChanged();
+      }
+    }
+  }
+
+  let testInternal = {
+    initialized: false,
+    mockManagedConfig: null
+  }
+
+  class ManagedConfigTestChromium {
+    constructor() {
+      Object.freeze(this);  // Make it immutable.
+    }
+
+    initialize() {
+      if (testInternal.mockManagedConfig !== null) {
+        testInternal.mockManagedConfig.reset();
+        return;
+      }
+
+      testInternal.mockManagedConfig = new MockManagedConfig;
+      testInternal.initialized = true;
+    }
+
+    setManagedConfig(config) {
+      testInternal.mockManagedConfig.setManagedConfig(config);
+    }
+
+    async nextObserverAdded() {
+      await new Promise(resolve => {
+        testInternal.mockManagedConfig.onObserverAdd_ = resolve;
+      });
+    }
+  }
+
+  return ManagedConfigTestChromium;
+})();
diff --git a/test/wpt/tests/resources/chromium/mock-pressure-service.js b/test/wpt/tests/resources/chromium/mock-pressure-service.js
new file mode 100644
index 0000000..02d10f8
--- /dev/null
+++ b/test/wpt/tests/resources/chromium/mock-pressure-service.js
@@ -0,0 +1,134 @@
+import {PressureManager, PressureManagerReceiver, PressureStatus} from '/gen/services/device/public/mojom/pressure_manager.mojom.m.js'
+import {PressureSource, PressureState} from '/gen/services/device/public/mojom/pressure_update.mojom.m.js'
+
+class MockPressureService {
+  constructor() {
+    this.receiver_ = new PressureManagerReceiver(this);
+    this.interceptor_ =
+        new MojoInterfaceInterceptor(PressureManager.$interfaceName);
+    this.interceptor_.oninterfacerequest = e => {
+      this.receiver_.$.bindHandle(e.handle);
+    };
+    this.reset();
+    this.mojomSourceType_ = new Map([['cpu', PressureSource.kCpu]]);
+    this.mojomStateType_ = new Map([
+      ['nominal', PressureState.kNominal], ['fair', PressureState.kFair],
+      ['serious', PressureState.kSerious], ['critical', PressureState.kCritical]
+    ]);
+    this.pressureServiceReadingTimerId_ = null;
+  }
+
+  start() {
+    this.interceptor_.start();
+  }
+
+  stop() {
+    this.stopPlatformCollector();
+    this.receiver_.$.close();
+    this.interceptor_.stop();
+
+    // Wait for an event loop iteration to let any pending mojo commands in
+    // the pressure service finish.
+    return new Promise(resolve => setTimeout(resolve, 0));
+  }
+
+  reset() {
+    this.observers_ = [];
+    this.pressureUpdate_ = null;
+    this.pressureServiceReadingTimerId_ = null;
+    this.pressureStatus_ = PressureStatus.kOk;
+    this.updatesDelivered_ = 0;
+  }
+
+  async addClient(observer, source) {
+    if (this.observers_.indexOf(observer) >= 0)
+      throw new Error('addClient() has already been called');
+
+    // TODO(crbug.com/1342184): Consider other sources.
+    // For now, "cpu" is the only source.
+    if (source !== PressureSource.kCpu)
+      throw new Error('Call addClient() with a wrong PressureSource');
+
+    observer.onConnectionError.addListener(() => {
+      // Remove this observer from observer array.
+      this.observers_.splice(this.observers_.indexOf(observer), 1);
+    });
+    this.observers_.push(observer);
+
+    return {status: this.pressureStatus_};
+  }
+
+  startPlatformCollector(sampleRate) {
+    if (sampleRate === 0)
+      return;
+
+    if (this.pressureServiceReadingTimerId_ != null)
+      this.stopPlatformCollector();
+
+    // The following code for calculating the timestamp was taken from
+    // https://source.chromium.org/chromium/chromium/src/+/main:third_party/
+    // blink/web_tests/http/tests/resources/
+    // geolocation-mock.js;l=131;drc=37a9b6c03b9bda9fcd62fc0e5e8016c278abd31f
+
+    // The new Date().getTime() returns the number of milliseconds since the
+    // UNIX epoch (1970-01-01 00::00:00 UTC), while |internalValue| of the
+    // device.mojom.PressureUpdate represents the value of microseconds since
+    // the Windows FILETIME epoch (1601-01-01 00:00:00 UTC). So add the delta
+    // when sets the |internalValue|. See more info in //base/time/time.h.
+    const windowsEpoch = Date.UTC(1601, 0, 1, 0, 0, 0, 0);
+    const unixEpoch = Date.UTC(1970, 0, 1, 0, 0, 0, 0);
+    // |epochDeltaInMs| equals to base::Time::kTimeTToMicrosecondsOffset.
+    const epochDeltaInMs = unixEpoch - windowsEpoch;
+
+    const timeout = (1 / sampleRate) * 1000;
+    this.pressureServiceReadingTimerId_ = self.setInterval(() => {
+      if (this.pressureUpdate_ === null || this.observers_.length === 0)
+        return;
+      this.pressureUpdate_.timestamp = {
+        internalValue: BigInt((new Date().getTime() + epochDeltaInMs) * 1000)
+      };
+      for (let observer of this.observers_)
+        observer.onPressureUpdated(this.pressureUpdate_);
+      this.updatesDelivered_++;
+    }, timeout);
+  }
+
+  stopPlatformCollector() {
+    if (this.pressureServiceReadingTimerId_ != null) {
+      self.clearInterval(this.pressureServiceReadingTimerId_);
+      this.pressureServiceReadingTimerId_ = null;
+    }
+    this.updatesDelivered_ = 0;
+  }
+
+  updatesDelivered() {
+    return this.updatesDelivered_;
+  }
+
+  setPressureUpdate(source, state) {
+    if (!this.mojomSourceType_.has(source))
+      throw new Error(`PressureSource '${source}' is invalid`);
+
+    if (!this.mojomStateType_.has(state))
+      throw new Error(`PressureState '${state}' is invalid`);
+
+    this.pressureUpdate_ = {
+      source: this.mojomSourceType_.get(source),
+      state: this.mojomStateType_.get(state),
+    };
+  }
+
+  setExpectedFailure(expectedException) {
+    assert_true(
+        expectedException instanceof DOMException,
+        'setExpectedFailure() expects a DOMException instance');
+    if (expectedException.name === 'NotSupportedError') {
+      this.pressureStatus_ = PressureStatus.kNotSupported;
+    } else {
+      throw new TypeError(
+          `Unexpected DOMException '${expectedException.name}'`);
+    }
+  }
+}
+
+export const mockPressureService = new MockPressureService();
diff --git a/test/wpt/tests/resources/chromium/mock-pressure-service.js.headers b/test/wpt/tests/resources/chromium/mock-pressure-service.js.headers
new file mode 100644
index 0000000..6805c32
--- /dev/null
+++ b/test/wpt/tests/resources/chromium/mock-pressure-service.js.headers
@@ -0,0 +1 @@
+Content-Type: text/javascript; charset=utf-8
diff --git a/test/wpt/tests/resources/chromium/mock-subapps.js b/test/wpt/tests/resources/chromium/mock-subapps.js
new file mode 100644
index 0000000..b819367
--- /dev/null
+++ b/test/wpt/tests/resources/chromium/mock-subapps.js
@@ -0,0 +1,89 @@
+'use strict';
+
+import {SubAppsService, SubAppsServiceReceiver, SubAppsServiceResultCode} from '/gen/third_party/blink/public/mojom/subapps/sub_apps_service.mojom.m.js';
+
+self.SubAppsServiceTest = (() => {
+  // Class that mocks SubAppsService interface defined in /third_party/blink/public/mojom/subapps/sub_apps_service.mojom
+
+  class MockSubAppsService {
+    constructor() {
+      this.interceptor_ =
+        new MojoInterfaceInterceptor(SubAppsService.$interfaceName);
+      this.receiver_ = new SubAppsServiceReceiver(this);
+      this.interceptor_.oninterfacerequest =
+        e => this.receiver_.$.bindHandle(e.handle);
+      this.interceptor_.start();
+    }
+
+    reset() {
+      this.interceptor_.stop();
+      this.receiver_.$.close();
+    }
+
+    add(sub_apps) {
+      return Promise.resolve({
+        result: testInternal.addCallReturnValue,
+      });
+    }
+
+    list() {
+      return Promise.resolve({
+        result: {
+          resultCode: testInternal.serviceResultCode,
+          subAppsList: testInternal.listCallReturnValue,
+        }
+      });
+    }
+
+    remove() {
+      return Promise.resolve({
+        result: testInternal.removeCallReturnValue,
+      });
+    }
+  }
+
+  let testInternal = {
+    initialized: false,
+    mockSubAppsService: null,
+    serviceResultCode: 0,
+    addCallReturnValue: [],
+    listCallReturnValue: [],
+    removeCallReturnValue: [],
+  }
+
+  class SubAppsServiceTestChromium {
+    constructor() {
+      Object.freeze(this);  // Make it immutable.
+    }
+
+    initialize(service_result_code, add_call_return_value, list_call_return_value, remove_call_return_value) {
+      if (!testInternal.initialized) {
+        testInternal = {
+          mockSubAppsService: new MockSubAppsService(),
+          initialized: true,
+          serviceResultCode: service_result_code,
+          addCallReturnValue: add_call_return_value,
+          listCallReturnValue: list_call_return_value,
+          removeCallReturnValue: remove_call_return_value,
+        };
+      };
+    }
+
+    async reset() {
+      if (testInternal.initialized) {
+        testInternal.mockSubAppsService.reset();
+        testInternal = {
+          mockSubAppsService: null,
+          initialized: false,
+          serviceResultCode: 0,
+          addCallReturnValue: [],
+          listCallReturnValue: [],
+          removeCallReturnValue: [],
+        };
+        await new Promise(resolve => setTimeout(resolve, 0));
+      }
+    }
+  }
+
+  return SubAppsServiceTestChromium;
+})();
diff --git a/test/wpt/tests/resources/chromium/mock-textdetection.js b/test/wpt/tests/resources/chromium/mock-textdetection.js
new file mode 100644
index 0000000..52ca987
--- /dev/null
+++ b/test/wpt/tests/resources/chromium/mock-textdetection.js
@@ -0,0 +1,92 @@
+import {TextDetection, TextDetectionReceiver} from '/gen/services/shape_detection/public/mojom/textdetection.mojom.m.js';
+
+self.TextDetectionTest = (() => {
+  // Class that mocks TextDetection interface defined in
+  // https://cs.chromium.org/chromium/src/services/shape_detection/public/mojom/textdetection.mojom
+  class MockTextDetection {
+    constructor() {
+      this.receiver_ = new TextDetectionReceiver(this);
+      this.interceptor_ =
+          new MojoInterfaceInterceptor(TextDetection.$interfaceName);
+      this.interceptor_.oninterfacerequest =
+          e => this.receiver_.$.bindHandle(e.handle);
+      this.interceptor_.start();
+    }
+
+    detect(bitmapData) {
+      this.bufferData_ =
+          new Uint32Array(getArrayBufferFromBigBuffer(bitmapData.pixelData));
+      return Promise.resolve({
+        results: [
+          {
+            rawValue : "cats",
+            boundingBox: { x: 1.0, y: 1.0, width: 100.0, height: 100.0 },
+            cornerPoints: [
+              { x: 1.0, y: 1.0 },
+              { x: 101.0, y: 1.0 },
+              { x: 101.0, y: 101.0 },
+              { x: 1.0, y: 101.0 }
+            ]
+          },
+          {
+            rawValue : "dogs",
+            boundingBox: { x: 2.0, y: 2.0, width: 50.0, height: 50.0 },
+            cornerPoints: [
+              { x: 2.0, y: 2.0 },
+              { x: 52.0, y: 2.0 },
+              { x: 52.0, y: 52.0 },
+              { x: 2.0, y: 52.0 }
+            ]
+          },
+        ],
+      });
+    }
+
+    getFrameData() {
+      return this.bufferData_;
+    }
+
+    reset() {
+      this.receiver_.$.close();
+      this.interceptor_.stop();
+    }
+
+  }
+
+  let testInternal = {
+    initialized: false,
+    MockTextDetection: null
+  }
+
+  class TextDetectionTestChromium {
+    constructor() {
+      Object.freeze(this); // Make it immutable.
+    }
+
+    initialize() {
+      if (testInternal.initialized)
+        throw new Error('Call reset() before initialize().');
+
+      testInternal.MockTextDetection = new MockTextDetection;
+      testInternal.initialized = true;
+    }
+
+    // Resets state of text detection mocks between test runs.
+    async reset() {
+      if (!testInternal.initialized)
+        throw new Error('Call initialize() before reset().');
+      testInternal.MockTextDetection.reset();
+      testInternal.MockTextDetection = null;
+      testInternal.initialized = false;
+
+      await new Promise(resolve => setTimeout(resolve, 0));
+    }
+
+    MockTextDetection() {
+      return testInternal.MockTextDetection;
+    }
+  }
+
+  return TextDetectionTestChromium;
+
+})();
diff --git a/test/wpt/tests/resources/chromium/mock-textdetection.js.headers b/test/wpt/tests/resources/chromium/mock-textdetection.js.headers
new file mode 100644
index 0000000..6c61a34
--- /dev/null
+++ b/test/wpt/tests/resources/chromium/mock-textdetection.js.headers
@@ -0,0 +1 @@
+Content-Type: text/javascript; charset=utf-8
\ No newline at end of file
diff --git a/test/wpt/tests/resources/chromium/nfc-mock.js b/test/wpt/tests/resources/chromium/nfc-mock.js
new file mode 100644
index 0000000..31a71b9
--- /dev/null
+++ b/test/wpt/tests/resources/chromium/nfc-mock.js
@@ -0,0 +1,437 @@
+import {NDEFErrorType, NDEFRecordTypeCategory, NFC, NFCReceiver} from '/gen/services/device/public/mojom/nfc.mojom.m.js';
+
+// Converts between NDEFMessageInit https://w3c.github.io/web-nfc/#dom-ndefmessage
+// and mojom.NDEFMessage structure, so that watch function can be tested.
+function toMojoNDEFMessage(message) {
+  let ndefMessage = {data: []};
+  for (let record of message.records) {
+    ndefMessage.data.push(toMojoNDEFRecord(record));
+  }
+  return ndefMessage;
+}
+
+function toMojoNDEFRecord(record) {
+  let nfcRecord = {};
+  // Simply checks the existence of ':' to decide whether it's an external
+  // type or a local type. As a mock, no need to really implement the validation
+  // algorithms for them.
+  if (record.recordType.startsWith(':')) {
+    nfcRecord.category = NDEFRecordTypeCategory.kLocal;
+  } else if (record.recordType.search(':') != -1) {
+    nfcRecord.category = NDEFRecordTypeCategory.kExternal;
+  } else {
+    nfcRecord.category = NDEFRecordTypeCategory.kStandardized;
+  }
+  nfcRecord.recordType = record.recordType;
+  nfcRecord.mediaType = record.mediaType;
+  nfcRecord.id = record.id;
+  if (record.recordType == 'text') {
+    nfcRecord.encoding = record.encoding == null? 'utf-8': record.encoding;
+    nfcRecord.lang = record.lang == null? 'en': record.lang;
+  }
+  nfcRecord.data = toByteArray(record.data);
+  if (record.data != null && record.data.records !== undefined) {
+    // |record.data| may be an NDEFMessageInit, i.e. the payload is a message.
+    nfcRecord.payloadMessage = toMojoNDEFMessage(record.data);
+  }
+  return nfcRecord;
+}
+
+// Converts JS objects to byte array.
+function toByteArray(data) {
+  if (data instanceof ArrayBuffer)
+    return new Uint8Array(data);
+  else if (ArrayBuffer.isView(data))
+    return new Uint8Array(data.buffer, data.byteOffset, data.byteLength);
+
+  let byteArray = new Uint8Array(0);
+  let tmpData = data;
+  if (typeof tmpData === 'object' || typeof tmpData === 'number')
+    tmpData = JSON.stringify(tmpData);
+
+  if (typeof tmpData === 'string')
+    byteArray = new TextEncoder().encode(tmpData);
+
+  return byteArray;
+}
+
+// Compares NDEFRecords that were provided / received by the mock service.
+// TODO: Use different getters to get received record data,
+// see spec changes at https://github.com/w3c/web-nfc/pull/243.
+self.compareNDEFRecords = function(providedRecord, receivedRecord) {
+  assert_equals(providedRecord.recordType, receivedRecord.recordType);
+
+  if (providedRecord.id === undefined) {
+    assert_equals(null, receivedRecord.id);
+  } else {
+    assert_equals(providedRecord.id, receivedRecord.id);
+  }
+
+  if (providedRecord.mediaType === undefined) {
+    assert_equals(null, receivedRecord.mediaType);
+  } else {
+    assert_equals(providedRecord.mediaType, receivedRecord.mediaType);
+  }
+
+  assert_not_equals(providedRecord.recordType, 'empty');
+
+  if (providedRecord.recordType == 'text') {
+    assert_equals(
+        providedRecord.encoding == null? 'utf-8': providedRecord.encoding,
+        receivedRecord.encoding);
+    assert_equals(providedRecord.lang == null? 'en': providedRecord.lang,
+                  receivedRecord.lang);
+  } else {
+    assert_equals(null, receivedRecord.encoding);
+    assert_equals(null, receivedRecord.lang);
+  }
+
+  assert_array_equals(toByteArray(providedRecord.data),
+                      new Uint8Array(receivedRecord.data));
+}
+
+// Compares NDEFWriteOptions structures that were provided to API and
+// received by the mock mojo service.
+self.assertNDEFWriteOptionsEqual = function(provided, received) {
+  if (provided.overwrite !== undefined)
+    assert_equals(provided.overwrite, !!received.overwrite);
+  else
+    assert_equals(!!received.overwrite, true);
+}
+
+// Compares NDEFReaderOptions structures that were provided to API and
+// received by the mock mojo service.
+self.assertNDEFReaderOptionsEqual = function(provided, received) {
+  if (provided.url !== undefined)
+    assert_equals(provided.url, received.url);
+  else
+    assert_equals(received.url, '');
+
+  if (provided.mediaType !== undefined)
+    assert_equals(provided.mediaType, received.mediaType);
+  else
+    assert_equals(received.mediaType, '');
+
+  if (provided.recordType !== undefined) {
+    assert_equals(provided.recordType, received.recordType);
+  }
+}
+
+function createNDEFError(type) {
+  return {error: (type != null ? {errorType: type, errorMessage: ''} : null)};
+}
+
+self.WebNFCTest = (() => {
+  class MockNFC {
+    constructor() {
+      this.receiver_ = new NFCReceiver(this);
+
+      this.interceptor_ = new MojoInterfaceInterceptor(NFC.$interfaceName);
+      this.interceptor_.oninterfacerequest = e => {
+        if (this.should_close_pipe_on_request_)
+          e.handle.close();
+        else
+          this.receiver_.$.bindHandle(e.handle);
+      }
+
+      this.interceptor_.start();
+
+      this.hw_status_ = NFCHWStatus.ENABLED;
+      this.pushed_message_ = null;
+      this.pending_write_options_ = null;
+      this.pending_push_promise_func_ = null;
+      this.push_completed_ = true;
+      this.pending_make_read_only_promise_func_ = null;
+      this.make_read_only_completed_ = true;
+      this.client_ = null;
+      this.watchers_ = [];
+      this.reading_messages_ = [];
+      this.operations_suspended_ = false;
+      this.is_formatted_tag_ = false;
+      this.data_transfer_failed_ = false;
+      this.should_close_pipe_on_request_ = false;
+    }
+
+    // NFC delegate functions.
+    async push(message, options) {
+      const error = this.getHWError();
+      if (error)
+        return error;
+      // Cancels previous pending push operation.
+      if (this.pending_push_promise_func_) {
+        this.cancelPendingPushOperation();
+      }
+
+      this.pushed_message_ = message;
+      this.pending_write_options_ = options;
+      return new Promise(resolve => {
+        if (this.operations_suspended_ || !this.push_completed_) {
+          // Leaves the push pending.
+          this.pending_push_promise_func_ = resolve;
+        } else if (this.is_formatted_tag_ && !options.overwrite) {
+          // Resolves with NotAllowedError if there are NDEF records on the device
+          // and overwrite is false.
+          resolve(createNDEFError(NDEFErrorType.NOT_ALLOWED));
+        } else if (this.data_transfer_failed_) {
+          // Resolves with NetworkError if data transfer fails.
+          resolve(createNDEFError(NDEFErrorType.IO_ERROR));
+        } else {
+          resolve(createNDEFError(null));
+        }
+      });
+    }
+
+    async cancelPush() {
+      this.cancelPendingPushOperation();
+      return createNDEFError(null);
+    }
+
+    async makeReadOnly(options) {
+      const error = this.getHWError();
+      if (error)
+        return error;
+      // Cancels previous pending makeReadOnly operation.
+      if (this.pending_make_read_only_promise_func_) {
+        this.cancelPendingMakeReadOnlyOperation();
+      }
+
+      if (this.operations_suspended_ || !this.make_read_only_completed_) {
+        // Leaves the makeReadOnly pending.
+        return new Promise(resolve => {
+          this.pending_make_read_only_promise_func_ = resolve;
+        });
+      } else if (this.data_transfer_failed_) {
+        // Resolves with NetworkError if data transfer fails.
+        return createNDEFError(NDEFErrorType.IO_ERROR);
+      } else {
+        return createNDEFError(null);
+      }
+    }
+
+    async cancelMakeReadOnly() {
+      this.cancelPendingMakeReadOnlyOperation();
+      return createNDEFError(null);
+    }
+
+    setClient(client) {
+      this.client_ = client;
+    }
+
+    async watch(id) {
+      assert_true(id > 0);
+      const error = this.getHWError();
+      if (error) {
+        return error;
+      }
+
+      this.watchers_.push({id: id});
+      // Ignores reading if NFC operation is suspended
+      // or the NFC tag does not expose NDEF technology.
+      if (!this.operations_suspended_) {
+        // Triggers onWatch if the new watcher matches existing messages.
+        for (let message of this.reading_messages_) {
+          this.client_.onWatch(
+              [id], fake_tag_serial_number, toMojoNDEFMessage(message));
+        }
+      }
+
+      return createNDEFError(null);
+    }
+
+    cancelWatch(id) {
+      let index = this.watchers_.findIndex(value => value.id === id);
+      if (index !== -1) {
+        this.watchers_.splice(index, 1);
+      }
+    }
+
+    getHWError() {
+      if (this.hw_status_ === NFCHWStatus.DISABLED)
+        return createNDEFError(NDEFErrorType.NOT_READABLE);
+      if (this.hw_status_ === NFCHWStatus.NOT_SUPPORTED)
+        return createNDEFError(NDEFErrorType.NOT_SUPPORTED);
+      return null;
+    }
+
+    setHWStatus(status) {
+      this.hw_status_ = status;
+    }
+
+    pushedMessage() {
+      return this.pushed_message_;
+    }
+
+    writeOptions() {
+      return this.pending_write_options_;
+    }
+
+    watchOptions() {
+      assert_not_equals(this.watchers_.length, 0);
+      return this.watchers_[this.watchers_.length - 1].options;
+    }
+
+    setPendingPushCompleted(result) {
+      this.push_completed_ = result;
+    }
+
+    setPendingMakeReadOnlyCompleted(result) {
+      this.make_read_only_completed_ = result;
+    }
+
+    reset() {
+      this.hw_status_ = NFCHWStatus.ENABLED;
+      this.watchers_ = [];
+      this.reading_messages_ = [];
+      this.operations_suspended_ = false;
+      this.cancelPendingPushOperation();
+      this.cancelPendingMakeReadOnlyOperation();
+      this.is_formatted_tag_ = false;
+      this.data_transfer_failed_ = false;
+      this.should_close_pipe_on_request_ = false;
+    }
+
+    cancelPendingPushOperation() {
+      if (this.pending_push_promise_func_) {
+        this.pending_push_promise_func_(
+            createNDEFError(NDEFErrorType.OPERATION_CANCELLED));
+        this.pending_push_promise_func_ = null;
+      }
+
+      this.pushed_message_ = null;
+      this.pending_write_options_ = null;
+      this.push_completed_ = true;
+    }
+
+    cancelPendingMakeReadOnlyOperation() {
+      if (this.pending_make_read_only_promise_func_) {
+        this.pending_make_read_only_promise_func_(
+            createNDEFError(NDEFErrorType.OPERATION_CANCELLED));
+        this.pending_make_read_only_promise_func_ = null;
+      }
+
+      this.make_read_only_completed_ = true;
+    }
+
+    // Sets message that is used to deliver NFC reading updates.
+    setReadingMessage(message) {
+      this.reading_messages_.push(message);
+      // Ignores reading if NFC operation is suspended.
+      if(this.operations_suspended_) return;
+      // when overwrite is false, the write algorithm will read the NFC tag
+      // to determine if it has NDEF records on it.
+      if (this.pending_write_options_ && this.pending_write_options_.overwrite)
+        return;
+      // Triggers onWatch if the new message matches existing watchers.
+      for (let watcher of this.watchers_) {
+        this.client_.onWatch(
+            [watcher.id], fake_tag_serial_number,
+            toMojoNDEFMessage(message));
+      }
+    }
+
+    // Suspends all pending NFC operations. Could be used when web page
+    // visibility is lost.
+    suspendNFCOperations() {
+      this.operations_suspended_ = true;
+    }
+
+    // Resumes all suspended NFC operations.
+    resumeNFCOperations() {
+      this.operations_suspended_ = false;
+      // Resumes pending NFC reading.
+      for (let watcher of this.watchers_) {
+        for (let message of this.reading_messages_) {
+          this.client_.onWatch(
+              [watcher.id], fake_tag_serial_number,
+              toMojoNDEFMessage(message));
+        }
+      }
+      // Resumes pending push operation.
+      if (this.pending_push_promise_func_ && this.push_completed_) {
+        this.pending_push_promise_func_(createNDEFError(null));
+        this.pending_push_promise_func_ = null;
+      }
+      // Resumes pending makeReadOnly operation.
+      if (this.pending_make_read_only_promise_func_ &&
+          this.make_read_only_completed_) {
+        this.pending_make_read_only_promise_func_(createNDEFError(null));
+        this.pending_make_read_only_promise_func_ = null;
+      }
+    }
+
+    // Simulates the device coming in proximity does not expose NDEF technology.
+    simulateNonNDEFTagDiscovered() {
+      // Notify NotSupportedError to all active readers.
+      if (this.watchers_.length != 0) {
+        this.client_.onError({
+          errorType: NDEFErrorType.NOT_SUPPORTED,
+          errorMessage: ''
+        });
+      }
+      // Reject the pending push with NotSupportedError.
+      if (this.pending_push_promise_func_) {
+        this.pending_push_promise_func_(
+            createNDEFError(NDEFErrorType.NOT_SUPPORTED));
+        this.pending_push_promise_func_ = null;
+      }
+      // Reject the pending makeReadOnly with NotSupportedError.
+      if (this.pending_make_read_only_promise_func_) {
+        this.pending_make_read_only_promise_func_(
+            createNDEFError(NDEFErrorType.NOT_SUPPORTED));
+        this.pending_make_read_only_promise_func_ = null;
+      }
+    }
+
+    setIsFormattedTag(isFormatted) {
+      this.is_formatted_tag_ = isFormatted;
+    }
+
+    simulateDataTransferFails() {
+      this.data_transfer_failed_ = true;
+    }
+
+    simulateClosedPipe() {
+      this.should_close_pipe_on_request_ = true;
+    }
+  }
+
+  let testInternal = {
+    initialized: false,
+    mockNFC: null
+  }
+
+  class NFCTestChromium {
+    constructor() {
+      Object.freeze(this); // Makes it immutable.
+    }
+
+    async initialize() {
+      if (testInternal.initialized)
+        throw new Error('Call reset() before initialize().');
+
+      // Grant nfc permissions for Chromium testdriver.
+      await test_driver.set_permission({ name: 'nfc' }, 'granted');
+
+      if (testInternal.mockNFC == null) {
+        testInternal.mockNFC = new MockNFC();
+      }
+      testInternal.initialized = true;
+    }
+
+    // Reuses the nfc mock but resets its state between test runs.
+    async reset() {
+      if (!testInternal.initialized)
+        throw new Error('Call initialize() before reset().');
+      testInternal.mockNFC.reset();
+      testInternal.initialized = false;
+
+      await new Promise(resolve => setTimeout(resolve, 0));
+    }
+
+    getMockNFC() {
+      return testInternal.mockNFC;
+    }
+  }
+
+  return NFCTestChromium;
+})();
diff --git a/test/wpt/tests/resources/chromium/web-bluetooth-test.js b/test/wpt/tests/resources/chromium/web-bluetooth-test.js
new file mode 100644
index 0000000..ecea5e7
--- /dev/null
+++ b/test/wpt/tests/resources/chromium/web-bluetooth-test.js
@@ -0,0 +1,629 @@
+'use strict';
+
+const content = {};
+const bluetooth = {};
+const MOJO_CHOOSER_EVENT_TYPE_MAP = {};
+
+function toMojoCentralState(state) {
+  switch (state) {
+    case 'absent':
+      return bluetooth.mojom.CentralState.ABSENT;
+    case 'powered-off':
+      return bluetooth.mojom.CentralState.POWERED_OFF;
+    case 'powered-on':
+      return bluetooth.mojom.CentralState.POWERED_ON;
+    default:
+      throw `Unsupported value ${state} for state.`;
+  }
+}
+
+// Converts bluetooth.mojom.WriteType to a string. If |writeType| is
+// invalid, this method will throw.
+function writeTypeToString(writeType) {
+  switch (writeType) {
+    case bluetooth.mojom.WriteType.kNone:
+      return 'none';
+    case bluetooth.mojom.WriteType.kWriteDefaultDeprecated:
+      return 'default-deprecated';
+    case bluetooth.mojom.WriteType.kWriteWithResponse:
+      return 'with-response';
+    case bluetooth.mojom.WriteType.kWriteWithoutResponse:
+      return 'without-response';
+    default:
+      throw `Unknown bluetooth.mojom.WriteType: ${writeType}`;
+  }
+}
+
+// Canonicalizes UUIDs and converts them to Mojo UUIDs.
+function canonicalizeAndConvertToMojoUUID(uuids) {
+  let canonicalUUIDs = uuids.map(val => ({uuid: BluetoothUUID.getService(val)}));
+  return canonicalUUIDs;
+}
+
+// Converts WebIDL a record<DOMString, BufferSource> to a map<K, array<uint8>> to
+// use for Mojo, where the value for K is calculated using keyFn.
+function convertToMojoMap(record, keyFn, isNumberKey = false) {
+  let map = new Map();
+  for (const [key, value] of Object.entries(record)) {
+    let buffer = ArrayBuffer.isView(value) ? value.buffer : value;
+    if (isNumberKey) {
+      let numberKey = parseInt(key);
+      if (Number.isNaN(numberKey))
+        throw `Map key ${key} is not a number`;
+      map.set(keyFn(numberKey), Array.from(new Uint8Array(buffer)));
+      continue;
+    }
+    map.set(keyFn(key), Array.from(new Uint8Array(buffer)));
+  }
+  return map;
+}
+
+function ArrayToMojoCharacteristicProperties(arr) {
+  const struct = {};
+  arr.forEach(property => { struct[property] = true; });
+  return struct;
+}
+
+class FakeBluetooth {
+  constructor() {
+    this.fake_bluetooth_ptr_ = new bluetooth.mojom.FakeBluetoothRemote();
+    this.fake_bluetooth_ptr_.$.bindNewPipeAndPassReceiver().bindInBrowser('process');
+    this.fake_central_ = null;
+  }
+
+  // Set it to indicate whether the platform supports BLE. For example,
+  // Windows 7 is a platform that doesn't support Low Energy. On the other
+  // hand Windows 10 is a platform that does support LE, even if there is no
+  // Bluetooth radio present.
+  async setLESupported(supported) {
+    if (typeof supported !== 'boolean') throw 'Type Not Supported';
+    await this.fake_bluetooth_ptr_.setLESupported(supported);
+  }
+
+  // Returns a promise that resolves with a FakeCentral that clients can use
+  // to simulate events that a device in the Central/Observer role would
+  // receive as well as monitor the operations performed by the device in the
+  // Central/Observer role.
+  // Calls sets LE as supported.
+  //
+  // A "Central" object would allow its clients to receive advertising events
+  // and initiate connections to peripherals i.e. operations of two roles
+  // defined by the Bluetooth Spec: Observer and Central.
+  // See Bluetooth 4.2 Vol 3 Part C 2.2.2 "Roles when Operating over an
+  // LE Physical Transport".
+  async simulateCentral({state}) {
+    if (this.fake_central_)
+      throw 'simulateCentral() should only be called once';
+
+    await this.setLESupported(true);
+
+    let {fakeCentral: fake_central_ptr} =
+      await this.fake_bluetooth_ptr_.simulateCentral(
+        toMojoCentralState(state));
+    this.fake_central_ = new FakeCentral(fake_central_ptr);
+    return this.fake_central_;
+  }
+
+  // Returns true if there are no pending responses.
+  async allResponsesConsumed() {
+    let {consumed} = await this.fake_bluetooth_ptr_.allResponsesConsumed();
+    return consumed;
+  }
+
+  // Returns a promise that resolves with a FakeChooser that clients can use to
+  // simulate chooser events.
+  async getManualChooser() {
+    if (typeof this.fake_chooser_ === 'undefined') {
+      this.fake_chooser_ = new FakeChooser();
+    }
+    return this.fake_chooser_;
+  }
+}
+
+// FakeCentral allows clients to simulate events that a device in the
+// Central/Observer role would receive as well as monitor the operations
+// performed by the device in the Central/Observer role.
+class FakeCentral {
+  constructor(fake_central_ptr) {
+    this.fake_central_ptr_ = fake_central_ptr;
+    this.peripherals_ = new Map();
+  }
+
+  // Simulates a peripheral with |address|, |name|, |manufacturerData| and
+  // |known_service_uuids| that has already been connected to the system. If the
+  // peripheral existed already it updates its name, manufacturer data, and
+  // known UUIDs. |known_service_uuids| should be an array of
+  // BluetoothServiceUUIDs
+  // https://webbluetoothcg.github.io/web-bluetooth/#typedefdef-bluetoothserviceuuid
+  //
+  // Platforms offer methods to retrieve devices that have already been
+  // connected to the system or weren't connected through the UA e.g. a user
+  // connected a peripheral through the system's settings. This method is
+  // intended to simulate peripherals that those methods would return.
+  async simulatePreconnectedPeripheral(
+      {address, name, manufacturerData = {}, knownServiceUUIDs = []}) {
+    await this.fake_central_ptr_.simulatePreconnectedPeripheral(
+        address, name,
+        convertToMojoMap(manufacturerData, Number, true /* isNumberKey */),
+        canonicalizeAndConvertToMojoUUID(knownServiceUUIDs));
+
+    return this.fetchOrCreatePeripheral_(address);
+  }
+
+  // Simulates an advertisement packet described by |scanResult| being received
+  // from a device. If central is currently scanning, the device will appear on
+  // the list of discovered devices.
+  async simulateAdvertisementReceived(scanResult) {
+    // Create a deep-copy to prevent the original |scanResult| from being
+    // modified when the UUIDs, manufacturer, and service data are converted.
+    let clonedScanResult = JSON.parse(JSON.stringify(scanResult));
+
+    if ('uuids' in scanResult.scanRecord) {
+      clonedScanResult.scanRecord.uuids =
+          canonicalizeAndConvertToMojoUUID(scanResult.scanRecord.uuids);
+    }
+
+    // Convert the optional appearance and txPower fields to the corresponding
+    // Mojo structures, since Mojo does not support optional interger values. If
+    // the fields are undefined, set the hasValue field as false and value as 0.
+    // Otherwise, set the hasValue field as true and value with the field value.
+    const has_appearance = 'appearance' in scanResult.scanRecord;
+    clonedScanResult.scanRecord.appearance = {
+      hasValue: has_appearance,
+      value: (has_appearance ? scanResult.scanRecord.appearance : 0)
+    }
+
+    const has_tx_power = 'txPower' in scanResult.scanRecord;
+    clonedScanResult.scanRecord.txPower = {
+      hasValue: has_tx_power,
+      value: (has_tx_power ? scanResult.scanRecord.txPower : 0)
+    }
+
+    // Convert manufacturerData from a record<DOMString, BufferSource> into a
+    // map<uint8, array<uint8>> for Mojo.
+    if ('manufacturerData' in scanResult.scanRecord) {
+      clonedScanResult.scanRecord.manufacturerData = convertToMojoMap(
+          scanResult.scanRecord.manufacturerData, Number,
+          true /* isNumberKey */);
+    }
+
+    // Convert serviceData from a record<DOMString, BufferSource> into a
+    // map<string, array<uint8>> for Mojo.
+    if ('serviceData' in scanResult.scanRecord) {
+      clonedScanResult.scanRecord.serviceData.serviceData = convertToMojoMap(
+          scanResult.scanRecord.serviceData, BluetoothUUID.getService,
+          false /* isNumberKey */);
+    }
+
+    await this.fake_central_ptr_.simulateAdvertisementReceived(
+        clonedScanResult);
+
+    return this.fetchOrCreatePeripheral_(clonedScanResult.deviceAddress);
+  }
+
+  // Simulates a change in the central device described by |state|. For example,
+  // setState('powered-off') can be used to simulate the central device powering
+  // off.
+  //
+  // This method should be used for any central state changes after
+  // simulateCentral() has been called to create a FakeCentral object.
+  async setState(state) {
+    await this.fake_central_ptr_.setState(toMojoCentralState(state));
+  }
+
+  // Create a fake_peripheral object from the given address.
+  fetchOrCreatePeripheral_(address) {
+    let peripheral = this.peripherals_.get(address);
+    if (peripheral === undefined) {
+      peripheral = new FakePeripheral(address, this.fake_central_ptr_);
+      this.peripherals_.set(address, peripheral);
+    }
+    return peripheral;
+  }
+}
+
+class FakePeripheral {
+  constructor(address, fake_central_ptr) {
+    this.address = address;
+    this.fake_central_ptr_ = fake_central_ptr;
+  }
+
+  // Adds a fake GATT Service with |uuid| to be discovered when discovering
+  // the peripheral's GATT Attributes. Returns a FakeRemoteGATTService
+  // corresponding to this service. |uuid| should be a BluetoothServiceUUIDs
+  // https://webbluetoothcg.github.io/web-bluetooth/#typedefdef-bluetoothserviceuuid
+  async addFakeService({uuid}) {
+    let {serviceId: service_id} = await this.fake_central_ptr_.addFakeService(
+      this.address, {uuid: BluetoothUUID.getService(uuid)});
+
+    if (service_id === null) throw 'addFakeService failed';
+
+    return new FakeRemoteGATTService(
+      service_id, this.address, this.fake_central_ptr_);
+  }
+
+  // Sets the next GATT Connection request response to |code|. |code| could be
+  // an HCI Error Code from BT 4.2 Vol 2 Part D 1.3 List Of Error Codes or a
+  // number outside that range returned by specific platforms e.g. Android
+  // returns 0x101 to signal a GATT failure
+  // https://developer.android.com/reference/android/bluetooth/BluetoothGatt.html#GATT_FAILURE
+  async setNextGATTConnectionResponse({code}) {
+    let {success} =
+      await this.fake_central_ptr_.setNextGATTConnectionResponse(
+        this.address, code);
+
+    if (success !== true) throw 'setNextGATTConnectionResponse failed.';
+  }
+
+  // Sets the next GATT Discovery request response for peripheral with
+  // |address| to |code|. |code| could be an HCI Error Code from
+  // BT 4.2 Vol 2 Part D 1.3 List Of Error Codes or a number outside that
+  // range returned by specific platforms e.g. Android returns 0x101 to signal
+  // a GATT failure
+  // https://developer.android.com/reference/android/bluetooth/BluetoothGatt.html#GATT_FAILURE
+  //
+  // The following procedures defined at BT 4.2 Vol 3 Part G Section 4.
+  // "GATT Feature Requirements" are used to discover attributes of the
+  // GATT Server:
+  //  - Primary Service Discovery
+  //  - Relationship Discovery
+  //  - Characteristic Discovery
+  //  - Characteristic Descriptor Discovery
+  // This method aims to simulate the response once all of these procedures
+  // have completed or if there was an error during any of them.
+  async setNextGATTDiscoveryResponse({code}) {
+    let {success} =
+      await this.fake_central_ptr_.setNextGATTDiscoveryResponse(
+        this.address, code);
+
+    if (success !== true) throw 'setNextGATTDiscoveryResponse failed.';
+  }
+
+  // Simulates a GATT disconnection from the peripheral with |address|.
+  async simulateGATTDisconnection() {
+    let {success} =
+      await this.fake_central_ptr_.simulateGATTDisconnection(this.address);
+
+    if (success !== true) throw 'simulateGATTDisconnection failed.';
+  }
+
+  // Simulates an Indication from the peripheral's GATT `Service Changed`
+  // Characteristic from BT 4.2 Vol 3 Part G 7.1. This Indication is signaled
+  // when services, characteristics, or descriptors are changed, added, or
+  // removed.
+  //
+  // The value for `Service Changed` is a range of attribute handles that have
+  // changed. However, this testing specification works at an abstracted
+  // level and does not expose setting attribute handles when adding
+  // attributes. Consequently, this simulate method should include the full
+  // range of all the peripheral's attribute handle values.
+  async simulateGATTServicesChanged() {
+    let {success} =
+      await this.fake_central_ptr_.simulateGATTServicesChanged(this.address);
+
+    if (success !== true) throw 'simulateGATTServicesChanged failed.';
+  }
+}
+
+class FakeRemoteGATTService {
+  constructor(service_id, peripheral_address, fake_central_ptr) {
+    this.service_id_ = service_id;
+    this.peripheral_address_ = peripheral_address;
+    this.fake_central_ptr_ = fake_central_ptr;
+  }
+
+  // Adds a fake GATT Characteristic with |uuid| and |properties|
+  // to this fake service. The characteristic will be found when discovering
+  // the peripheral's GATT Attributes. Returns a FakeRemoteGATTCharacteristic
+  // corresponding to the added characteristic.
+  async addFakeCharacteristic({uuid, properties}) {
+    let {characteristicId: characteristic_id} =
+        await this.fake_central_ptr_.addFakeCharacteristic(
+            {uuid: BluetoothUUID.getCharacteristic(uuid)},
+            ArrayToMojoCharacteristicProperties(properties),
+            this.service_id_,
+            this.peripheral_address_);
+
+    if (characteristic_id === null) throw 'addFakeCharacteristic failed';
+
+    return new FakeRemoteGATTCharacteristic(
+      characteristic_id, this.service_id_,
+      this.peripheral_address_, this.fake_central_ptr_);
+  }
+
+  // Removes the fake GATT service from its fake peripheral.
+  async remove() {
+    let {success} =
+        await this.fake_central_ptr_.removeFakeService(
+            this.service_id_,
+            this.peripheral_address_);
+
+    if (!success) throw 'remove failed';
+  }
+}
+
+class FakeRemoteGATTCharacteristic {
+  constructor(characteristic_id, service_id, peripheral_address,
+      fake_central_ptr) {
+    this.ids_ = [characteristic_id, service_id, peripheral_address];
+    this.descriptors_ = [];
+    this.fake_central_ptr_ = fake_central_ptr;
+  }
+
+  // Adds a fake GATT Descriptor with |uuid| to be discovered when
+  // discovering the peripheral's GATT Attributes. Returns a
+  // FakeRemoteGATTDescriptor corresponding to this descriptor. |uuid| should
+  // be a BluetoothDescriptorUUID
+  // https://webbluetoothcg.github.io/web-bluetooth/#typedefdef-bluetoothdescriptoruuid
+  async addFakeDescriptor({uuid}) {
+    let {descriptorId: descriptor_id} =
+        await this.fake_central_ptr_.addFakeDescriptor(
+            {uuid: BluetoothUUID.getDescriptor(uuid)}, ...this.ids_);
+
+    if (descriptor_id === null) throw 'addFakeDescriptor failed';
+
+    let fake_descriptor = new FakeRemoteGATTDescriptor(
+      descriptor_id, ...this.ids_, this.fake_central_ptr_);
+    this.descriptors_.push(fake_descriptor);
+
+    return fake_descriptor;
+  }
+
+  // Sets the next read response for characteristic to |code| and |value|.
+  // |code| could be a GATT Error Response from
+  // BT 4.2 Vol 3 Part F 3.4.1.1 Error Response or a number outside that range
+  // returned by specific platforms e.g. Android returns 0x101 to signal a GATT
+  // failure.
+  // https://developer.android.com/reference/android/bluetooth/BluetoothGatt.html#GATT_FAILURE
+  async setNextReadResponse(gatt_code, value=null) {
+    if (gatt_code === 0 && value === null) {
+      throw '|value| can\'t be null if read should success.';
+    }
+    if (gatt_code !== 0 && value !== null) {
+      throw '|value| must be null if read should fail.';
+    }
+
+    let {success} =
+      await this.fake_central_ptr_.setNextReadCharacteristicResponse(
+        gatt_code, value, ...this.ids_);
+
+    if (!success) throw 'setNextReadCharacteristicResponse failed';
+  }
+
+  // Sets the next write response for this characteristic to |code|. If
+  // writing to a characteristic that only supports 'write_without_response'
+  // the set response will be ignored.
+  // |code| could be a GATT Error Response from
+  // BT 4.2 Vol 3 Part F 3.4.1.1 Error Response or a number outside that range
+  // returned by specific platforms e.g. Android returns 0x101 to signal a GATT
+  // failure.
+  async setNextWriteResponse(gatt_code) {
+    let {success} =
+      await this.fake_central_ptr_.setNextWriteCharacteristicResponse(
+        gatt_code, ...this.ids_);
+
+    if (!success) throw 'setNextWriteCharacteristicResponse failed';
+  }
+
+  // Sets the next subscribe to notifications response for characteristic with
+  // |characteristic_id| in |service_id| and in |peripheral_address| to
+  // |code|. |code| could be a GATT Error Response from BT 4.2 Vol 3 Part F
+  // 3.4.1.1 Error Response or a number outside that range returned by
+  // specific platforms e.g. Android returns 0x101 to signal a GATT failure.
+  async setNextSubscribeToNotificationsResponse(gatt_code) {
+    let {success} =
+      await this.fake_central_ptr_.setNextSubscribeToNotificationsResponse(
+        gatt_code, ...this.ids_);
+
+    if (!success) throw 'setNextSubscribeToNotificationsResponse failed';
+  }
+
+  // Sets the next unsubscribe to notifications response for characteristic with
+  // |characteristic_id| in |service_id| and in |peripheral_address| to
+  // |code|. |code| could be a GATT Error Response from BT 4.2 Vol 3 Part F
+  // 3.4.1.1 Error Response or a number outside that range returned by
+  // specific platforms e.g. Android returns 0x101 to signal a GATT failure.
+  async setNextUnsubscribeFromNotificationsResponse(gatt_code) {
+    let {success} =
+      await this.fake_central_ptr_.setNextUnsubscribeFromNotificationsResponse(
+        gatt_code, ...this.ids_);
+
+    if (!success) throw 'setNextUnsubscribeToNotificationsResponse failed';
+  }
+
+  // Returns true if notifications from the characteristic have been subscribed
+  // to.
+  async isNotifying() {
+    let {success, isNotifying} =
+        await this.fake_central_ptr_.isNotifying(...this.ids_);
+
+    if (!success) throw 'isNotifying failed';
+
+    return isNotifying;
+  }
+
+  // Gets the last successfully written value to the characteristic and its
+  // write type. Write type is one of 'none', 'default-deprecated',
+  // 'with-response', 'without-response'. Returns {lastValue: null,
+  // lastWriteType: 'none'} if no value has yet been written to the
+  // characteristic.
+  async getLastWrittenValue() {
+    let {success, value, writeType} =
+        await this.fake_central_ptr_.getLastWrittenCharacteristicValue(
+            ...this.ids_);
+
+    if (!success) throw 'getLastWrittenCharacteristicValue failed';
+
+    return {lastValue: value, lastWriteType: writeTypeToString(writeType)};
+  }
+
+  // Removes the fake GATT Characteristic from its fake service.
+  async remove() {
+    let {success} =
+        await this.fake_central_ptr_.removeFakeCharacteristic(...this.ids_);
+
+    if (!success) throw 'remove failed';
+  }
+}
+
+class FakeRemoteGATTDescriptor {
+  constructor(descriptor_id,
+              characteristic_id,
+              service_id,
+              peripheral_address,
+              fake_central_ptr) {
+    this.ids_ = [
+      descriptor_id, characteristic_id, service_id, peripheral_address];
+    this.fake_central_ptr_ = fake_central_ptr;
+  }
+
+  // Sets the next read response for descriptor to |code| and |value|.
+  // |code| could be a GATT Error Response from
+  // BT 4.2 Vol 3 Part F 3.4.1.1 Error Response or a number outside that range
+  // returned by specific platforms e.g. Android returns 0x101 to signal a GATT
+  // failure.
+  // https://developer.android.com/reference/android/bluetooth/BluetoothGatt.html#GATT_FAILURE
+  async setNextReadResponse(gatt_code, value=null) {
+    if (gatt_code === 0 && value === null) {
+      throw '|value| cannot be null if read should succeed.';
+    }
+    if (gatt_code !== 0 && value !== null) {
+      throw '|value| must be null if read should fail.';
+    }
+
+    let {success} =
+      await this.fake_central_ptr_.setNextReadDescriptorResponse(
+        gatt_code, value, ...this.ids_);
+
+    if (!success) throw 'setNextReadDescriptorResponse failed';
+  }
+
+  // Sets the next write response for this descriptor to |code|.
+  // |code| could be a GATT Error Response from
+  // BT 4.2 Vol 3 Part F 3.4.1.1 Error Response or a number outside that range
+  // returned by specific platforms e.g. Android returns 0x101 to signal a GATT
+  // failure.
+  async setNextWriteResponse(gatt_code) {
+    let {success} =
+      await this.fake_central_ptr_.setNextWriteDescriptorResponse(
+        gatt_code, ...this.ids_);
+
+    if (!success) throw 'setNextWriteDescriptorResponse failed';
+  }
+
+  // Gets the last successfully written value to the descriptor.
+  // Returns null if no value has yet been written to the descriptor.
+  async getLastWrittenValue() {
+    let {success, value} =
+      await this.fake_central_ptr_.getLastWrittenDescriptorValue(
+          ...this.ids_);
+
+    if (!success) throw 'getLastWrittenDescriptorValue failed';
+
+    return value;
+  }
+
+  // Removes the fake GATT Descriptor from its fake characteristic.
+  async remove() {
+    let {success} =
+        await this.fake_central_ptr_.removeFakeDescriptor(...this.ids_);
+
+    if (!success) throw 'remove failed';
+  }
+}
+
+// FakeChooser allows clients to simulate user actions on a Bluetooth chooser,
+// and records the events produced by the Bluetooth chooser.
+class FakeChooser {
+  constructor() {
+    let fakeBluetoothChooserFactoryRemote =
+        new content.mojom.FakeBluetoothChooserFactoryRemote();
+    fakeBluetoothChooserFactoryRemote.$.bindNewPipeAndPassReceiver().bindInBrowser('process');
+
+    this.fake_bluetooth_chooser_ptr_ =
+        new content.mojom.FakeBluetoothChooserRemote();
+    this.fake_bluetooth_chooser_client_receiver_ =
+        new content.mojom.FakeBluetoothChooserClientReceiver(this);
+    fakeBluetoothChooserFactoryRemote.createFakeBluetoothChooser(
+        this.fake_bluetooth_chooser_ptr_.$.bindNewPipeAndPassReceiver(),
+        this.fake_bluetooth_chooser_client_receiver_.$.associateAndPassRemote());
+
+    this.events_ = new Array();
+    this.event_listener_ = null;
+  }
+
+  // If the chooser has received more events than |numOfEvents| this function
+  // will reject the promise, else it will wait until |numOfEvents| events are
+  // received before resolving with an array of |FakeBluetoothChooserEvent|
+  // objects.
+  async waitForEvents(numOfEvents) {
+    return new Promise(resolve => {
+      if (this.events_.length > numOfEvents) {
+        throw `Asked for ${numOfEvents} event(s), but received ` +
+            `${this.events_.length}.`;
+      }
+
+      this.event_listener_ = () => {
+         if (this.events_.length === numOfEvents) {
+          let result = Array.from(this.events_);
+          this.event_listener_ = null;
+          this.events_ = [];
+          resolve(result);
+        }
+      };
+      this.event_listener_();
+    });
+  }
+
+  async selectPeripheral(peripheral) {
+    if (!(peripheral instanceof FakePeripheral)) {
+      throw '|peripheral| must be an instance of FakePeripheral';
+    }
+    await this.fake_bluetooth_chooser_ptr_.selectPeripheral(peripheral.address);
+  }
+
+  async cancel() {
+    await this.fake_bluetooth_chooser_ptr_.cancel();
+  }
+
+  async rescan() {
+    await this.fake_bluetooth_chooser_ptr_.rescan();
+  }
+
+  onEvent(chooserEvent) {
+    chooserEvent.type = MOJO_CHOOSER_EVENT_TYPE_MAP[chooserEvent.type];
+    this.events_.push(chooserEvent);
+    if (this.event_listener_ !== null) {
+      this.event_listener_();
+    }
+  }
+}
+
+async function initializeChromiumResources() {
+  content.mojom = await import(
+      '/gen/content/web_test/common/fake_bluetooth_chooser.mojom.m.js');
+  bluetooth.mojom = await import(
+      '/gen/device/bluetooth/public/mojom/test/fake_bluetooth.mojom.m.js');
+
+  const map = MOJO_CHOOSER_EVENT_TYPE_MAP;
+  const types = content.mojom.ChooserEventType;
+  map[types.CHOOSER_OPENED] = 'chooser-opened';
+  map[types.CHOOSER_CLOSED] = 'chooser-closed';
+  map[types.ADAPTER_REMOVED] = 'adapter-removed';
+  map[types.ADAPTER_DISABLED] = 'adapter-disabled';
+  map[types.ADAPTER_ENABLED] = 'adapter-enabled';
+  map[types.DISCOVERY_FAILED_TO_START] = 'discovery-failed-to-start';
+  map[types.DISCOVERING] = 'discovering';
+  map[types.DISCOVERY_IDLE] = 'discovery-idle';
+  map[types.ADD_OR_UPDATE_DEVICE] = 'add-or-update-device';
+
+  // If this line fails, it means that current environment does not support the
+  // Web Bluetooth Test API.
+  try {
+    navigator.bluetooth.test = new FakeBluetooth();
+  } catch {
+    throw 'Web Bluetooth Test API is not implemented on this ' +
+        'environment. See the bluetooth README at ' +
+        'https://github.com/web-platform-tests/wpt/blob/master/bluetooth/README.md#web-bluetooth-testing';
+  }
+}
diff --git a/test/wpt/tests/resources/chromium/web-bluetooth-test.js.headers b/test/wpt/tests/resources/chromium/web-bluetooth-test.js.headers
new file mode 100644
index 0000000..6805c32
--- /dev/null
+++ b/test/wpt/tests/resources/chromium/web-bluetooth-test.js.headers
@@ -0,0 +1 @@
+Content-Type: text/javascript; charset=utf-8
diff --git a/test/wpt/tests/resources/chromium/webusb-child-test.js b/test/wpt/tests/resources/chromium/webusb-child-test.js
new file mode 100644
index 0000000..21412f6
--- /dev/null
+++ b/test/wpt/tests/resources/chromium/webusb-child-test.js
@@ -0,0 +1,47 @@
+'use strict';
+
+// This polyfill prepares a child context to be attached to a parent context.
+// The parent must call navigator.usb.test.attachToContext() to attach to the
+// child context.
+(() => {
+  if (this.constructor.name === 'DedicatedWorkerGlobalScope' ||
+      this !== window.top) {
+
+    // Run Chromium specific set up code.
+    if (typeof MojoInterfaceInterceptor !== 'undefined') {
+      let messageChannel = new MessageChannel();
+      messageChannel.port1.onmessage = async (messageEvent) => {
+        if (messageEvent.data.type === 'Attach') {
+          messageEvent.data.interfaces.forEach(interfaceName => {
+            let interfaceInterceptor =
+                new MojoInterfaceInterceptor(interfaceName);
+            interfaceInterceptor.oninterfacerequest =
+              e => messageChannel.port1.postMessage({
+                type: interfaceName,
+                handle: e.handle
+              }, [e.handle]);
+            interfaceInterceptor.start();
+          });
+
+          // Wait for a call to GetDevices() to ensure that the interface
+          // handles are forwarded to the parent context.
+          try {
+            await navigator.usb.getDevices();
+          } catch (e) {
+            // This can happen in case of, for example, testing usb disallowed
+            // iframe.
+            console.error(`getDevices() throws error: ${e.name}: ${e.message}`);
+          }
+
+          messageChannel.port1.postMessage({ type: 'Complete' });
+        }
+      };
+
+      let message = { type: 'ReadyForAttachment', port: messageChannel.port2 };
+      if (typeof Window !== 'undefined')
+        parent.postMessage(message, '*', [messageChannel.port2]);
+      else
+        postMessage(message, [messageChannel.port2]);
+    }
+  }
+})();
diff --git a/test/wpt/tests/resources/chromium/webusb-child-test.js.headers b/test/wpt/tests/resources/chromium/webusb-child-test.js.headers
new file mode 100644
index 0000000..6805c32
--- /dev/null
+++ b/test/wpt/tests/resources/chromium/webusb-child-test.js.headers
@@ -0,0 +1 @@
+Content-Type: text/javascript; charset=utf-8
diff --git a/test/wpt/tests/resources/chromium/webusb-test.js b/test/wpt/tests/resources/chromium/webusb-test.js
new file mode 100644
index 0000000..7cca63d
--- /dev/null
+++ b/test/wpt/tests/resources/chromium/webusb-test.js
@@ -0,0 +1,583 @@
+'use strict';
+
+// This polyfill library implements the WebUSB Test API as specified here:
+// https://wicg.github.io/webusb/test/
+
+(() => {
+
+// These variables are logically members of the USBTest class but are defined
+// here to hide them from being visible as fields of navigator.usb.test.
+let internal = {
+  intialized: false,
+
+  webUsbService: null,
+  webUsbServiceInterceptor: null,
+
+  messagePort: null,
+};
+
+let mojom = {};
+
+async function loadMojomDefinitions() {
+  const deviceMojom =
+      await import('/gen/services/device/public/mojom/usb_device.mojom.m.js');
+  const serviceMojom = await import(
+      '/gen/third_party/blink/public/mojom/usb/web_usb_service.mojom.m.js');
+  return {
+    ...deviceMojom,
+    ...serviceMojom,
+  };
+}
+
+function getMessagePort(target) {
+  return new Promise(resolve => {
+    target.addEventListener('message', messageEvent => {
+      if (messageEvent.data.type === 'ReadyForAttachment') {
+        if (internal.messagePort === null) {
+          internal.messagePort = messageEvent.data.port;
+        }
+        resolve();
+      }
+    }, {once: true});
+  });
+}
+
+// Converts an ECMAScript String object to an instance of
+// mojo_base.mojom.String16.
+function mojoString16ToString(string16) {
+  return String.fromCharCode.apply(null, string16.data);
+}
+
+// Converts an instance of mojo_base.mojom.String16 to an ECMAScript String.
+function stringToMojoString16(string) {
+  let array = new Array(string.length);
+  for (var i = 0; i < string.length; ++i) {
+    array[i] = string.charCodeAt(i);
+  }
+  return { data: array }
+}
+
+function fakeDeviceInitToDeviceInfo(guid, init) {
+  let deviceInfo = {
+    guid: guid + "",
+    usbVersionMajor: init.usbVersionMajor,
+    usbVersionMinor: init.usbVersionMinor,
+    usbVersionSubminor: init.usbVersionSubminor,
+    classCode: init.deviceClass,
+    subclassCode: init.deviceSubclass,
+    protocolCode: init.deviceProtocol,
+    vendorId: init.vendorId,
+    productId: init.productId,
+    deviceVersionMajor: init.deviceVersionMajor,
+    deviceVersionMinor: init.deviceVersionMinor,
+    deviceVersionSubminor: init.deviceVersionSubminor,
+    manufacturerName: stringToMojoString16(init.manufacturerName),
+    productName: stringToMojoString16(init.productName),
+    serialNumber: stringToMojoString16(init.serialNumber),
+    activeConfiguration: init.activeConfigurationValue,
+    configurations: []
+  };
+  init.configurations.forEach(config => {
+    var configInfo = {
+      configurationValue: config.configurationValue,
+      configurationName: stringToMojoString16(config.configurationName),
+      selfPowered: false,
+      remoteWakeup: false,
+      maximumPower: 0,
+      interfaces: [],
+      extraData: new Uint8Array()
+    };
+    config.interfaces.forEach(iface => {
+      var interfaceInfo = {
+        interfaceNumber: iface.interfaceNumber,
+        alternates: []
+      };
+      iface.alternates.forEach(alternate => {
+        var alternateInfo = {
+          alternateSetting: alternate.alternateSetting,
+          classCode: alternate.interfaceClass,
+          subclassCode: alternate.interfaceSubclass,
+          protocolCode: alternate.interfaceProtocol,
+          interfaceName: stringToMojoString16(alternate.interfaceName),
+          endpoints: [],
+          extraData: new Uint8Array()
+        };
+        alternate.endpoints.forEach(endpoint => {
+          var endpointInfo = {
+            endpointNumber: endpoint.endpointNumber,
+            packetSize: endpoint.packetSize,
+            synchronizationType: mojom.UsbSynchronizationType.NONE,
+            usageType: mojom.UsbUsageType.DATA,
+            pollingInterval: 0,
+            extraData: new Uint8Array()
+          };
+          switch (endpoint.direction) {
+            case "in":
+              endpointInfo.direction = mojom.UsbTransferDirection.INBOUND;
+              break;
+            case "out":
+              endpointInfo.direction = mojom.UsbTransferDirection.OUTBOUND;
+              break;
+          }
+          switch (endpoint.type) {
+            case "bulk":
+              endpointInfo.type = mojom.UsbTransferType.BULK;
+              break;
+            case "interrupt":
+              endpointInfo.type = mojom.UsbTransferType.INTERRUPT;
+              break;
+            case "isochronous":
+              endpointInfo.type = mojom.UsbTransferType.ISOCHRONOUS;
+              break;
+          }
+          alternateInfo.endpoints.push(endpointInfo);
+        });
+        interfaceInfo.alternates.push(alternateInfo);
+      });
+      configInfo.interfaces.push(interfaceInfo);
+    });
+    deviceInfo.configurations.push(configInfo);
+  });
+  return deviceInfo;
+}
+
+function convertMojoDeviceFilters(input) {
+  let output = [];
+  input.forEach(filter => {
+    output.push(convertMojoDeviceFilter(filter));
+  });
+  return output;
+}
+
+function convertMojoDeviceFilter(input) {
+  let output = {};
+  if (input.hasVendorId)
+    output.vendorId = input.vendorId;
+  if (input.hasProductId)
+    output.productId = input.productId;
+  if (input.hasClassCode)
+    output.classCode = input.classCode;
+  if (input.hasSubclassCode)
+    output.subclassCode = input.subclassCode;
+  if (input.hasProtocolCode)
+    output.protocolCode = input.protocolCode;
+  if (input.serialNumber)
+    output.serialNumber = mojoString16ToString(input.serialNumber);
+  return output;
+}
+
+class FakeDevice {
+  constructor(deviceInit) {
+    this.info_ = deviceInit;
+    this.opened_ = false;
+    this.currentConfiguration_ = null;
+    this.claimedInterfaces_ = new Map();
+  }
+
+  getConfiguration() {
+    if (this.currentConfiguration_) {
+      return Promise.resolve({
+          value: this.currentConfiguration_.configurationValue });
+    } else {
+      return Promise.resolve({ value: 0 });
+    }
+  }
+
+  open() {
+    assert_false(this.opened_);
+    this.opened_ = true;
+    return Promise.resolve({result: {success: mojom.UsbOpenDeviceSuccess.OK}});
+  }
+
+  close() {
+    assert_true(this.opened_);
+    this.opened_ = false;
+    return Promise.resolve();
+  }
+
+  setConfiguration(value) {
+    assert_true(this.opened_);
+
+    let selectedConfiguration = this.info_.configurations.find(
+        configuration => configuration.configurationValue == value);
+    // Blink should never request an invalid configuration.
+    assert_not_equals(selectedConfiguration, undefined);
+    this.currentConfiguration_ = selectedConfiguration;
+    return Promise.resolve({ success: true });
+  }
+
+  async claimInterface(interfaceNumber) {
+    assert_true(this.opened_);
+    assert_false(this.currentConfiguration_ == null, 'device configured');
+    assert_false(this.claimedInterfaces_.has(interfaceNumber),
+                 'interface already claimed');
+
+    const protectedInterfaces = new Set([
+      mojom.USB_AUDIO_CLASS,
+      mojom.USB_HID_CLASS,
+      mojom.USB_MASS_STORAGE_CLASS,
+      mojom.USB_SMART_CARD_CLASS,
+      mojom.USB_VIDEO_CLASS,
+      mojom.USB_AUDIO_VIDEO_CLASS,
+      mojom.USB_WIRELESS_CLASS,
+    ]);
+
+    let iface = this.currentConfiguration_.interfaces.find(
+        iface => iface.interfaceNumber == interfaceNumber);
+    // Blink should never request an invalid interface or alternate.
+    assert_false(iface == undefined);
+    if (iface.alternates.some(
+            alt => protectedInterfaces.has(alt.interfaceClass))) {
+      return {result: mojom.UsbClaimInterfaceResult.kProtectedClass};
+    }
+
+    this.claimedInterfaces_.set(interfaceNumber, 0);
+    return {result: mojom.UsbClaimInterfaceResult.kSuccess};
+  }
+
+  releaseInterface(interfaceNumber) {
+    assert_true(this.opened_);
+    assert_false(this.currentConfiguration_ == null, 'device configured');
+    assert_true(this.claimedInterfaces_.has(interfaceNumber));
+    this.claimedInterfaces_.delete(interfaceNumber);
+    return Promise.resolve({ success: true });
+  }
+
+  setInterfaceAlternateSetting(interfaceNumber, alternateSetting) {
+    assert_true(this.opened_);
+    assert_false(this.currentConfiguration_ == null, 'device configured');
+    assert_true(this.claimedInterfaces_.has(interfaceNumber));
+
+    let iface = this.currentConfiguration_.interfaces.find(
+        iface => iface.interfaceNumber == interfaceNumber);
+    // Blink should never request an invalid interface or alternate.
+    assert_false(iface == undefined);
+    assert_true(iface.alternates.some(
+        x => x.alternateSetting == alternateSetting));
+    this.claimedInterfaces_.set(interfaceNumber, alternateSetting);
+    return Promise.resolve({ success: true });
+  }
+
+  reset() {
+    assert_true(this.opened_);
+    return Promise.resolve({ success: true });
+  }
+
+  clearHalt(endpoint) {
+    assert_true(this.opened_);
+    assert_false(this.currentConfiguration_ == null, 'device configured');
+    // TODO(reillyg): Assert that endpoint is valid.
+    return Promise.resolve({ success: true });
+  }
+
+  async controlTransferIn(params, length, timeout) {
+    assert_true(this.opened_);
+
+    if ((params.recipient == mojom.UsbControlTransferRecipient.INTERFACE ||
+         params.recipient == mojom.UsbControlTransferRecipient.ENDPOINT) &&
+        this.currentConfiguration_ == null) {
+      return {
+        status: mojom.UsbTransferStatus.PERMISSION_DENIED,
+      };
+    }
+
+    return {
+      status: mojom.UsbTransferStatus.OK,
+      data: {
+        buffer: [
+          length >> 8, length & 0xff, params.request, params.value >> 8,
+          params.value & 0xff, params.index >> 8, params.index & 0xff
+        ]
+      }
+    };
+  }
+
+  async controlTransferOut(params, data, timeout) {
+    assert_true(this.opened_);
+
+    if ((params.recipient == mojom.UsbControlTransferRecipient.INTERFACE ||
+         params.recipient == mojom.UsbControlTransferRecipient.ENDPOINT) &&
+        this.currentConfiguration_ == null) {
+      return {
+        status: mojom.UsbTransferStatus.PERMISSION_DENIED,
+      };
+    }
+
+    return {status: mojom.UsbTransferStatus.OK, bytesWritten: data.byteLength};
+  }
+
+  genericTransferIn(endpointNumber, length, timeout) {
+    assert_true(this.opened_);
+    assert_false(this.currentConfiguration_ == null, 'device configured');
+    // TODO(reillyg): Assert that endpoint is valid.
+    let data = new Array(length);
+    for (let i = 0; i < length; ++i)
+      data[i] = i & 0xff;
+    return Promise.resolve(
+        {status: mojom.UsbTransferStatus.OK, data: {buffer: data}});
+  }
+
+  genericTransferOut(endpointNumber, data, timeout) {
+    assert_true(this.opened_);
+    assert_false(this.currentConfiguration_ == null, 'device configured');
+    // TODO(reillyg): Assert that endpoint is valid.
+    return Promise.resolve(
+        {status: mojom.UsbTransferStatus.OK, bytesWritten: data.byteLength});
+  }
+
+  isochronousTransferIn(endpointNumber, packetLengths, timeout) {
+    assert_true(this.opened_);
+    assert_false(this.currentConfiguration_ == null, 'device configured');
+    // TODO(reillyg): Assert that endpoint is valid.
+    let data = new Array(packetLengths.reduce((a, b) => a + b, 0));
+    let dataOffset = 0;
+    let packets = new Array(packetLengths.length);
+    for (let i = 0; i < packetLengths.length; ++i) {
+      for (let j = 0; j < packetLengths[i]; ++j)
+        data[dataOffset++] = j & 0xff;
+      packets[i] = {
+        length: packetLengths[i],
+        transferredLength: packetLengths[i],
+        status: mojom.UsbTransferStatus.OK
+      };
+    }
+    return Promise.resolve({data: {buffer: data}, packets: packets});
+  }
+
+  isochronousTransferOut(endpointNumber, data, packetLengths, timeout) {
+    assert_true(this.opened_);
+    assert_false(this.currentConfiguration_ == null, 'device configured');
+    // TODO(reillyg): Assert that endpoint is valid.
+    let packets = new Array(packetLengths.length);
+    for (let i = 0; i < packetLengths.length; ++i) {
+      packets[i] = {
+        length: packetLengths[i],
+        transferredLength: packetLengths[i],
+        status: mojom.UsbTransferStatus.OK
+      };
+    }
+    return Promise.resolve({ packets: packets });
+  }
+}
+
+class FakeWebUsbService {
+  constructor() {
+    this.receiver_ = new mojom.WebUsbServiceReceiver(this);
+    this.devices_ = new Map();
+    this.devicesByGuid_ = new Map();
+    this.client_ = null;
+    this.nextGuid_ = 0;
+  }
+
+  addBinding(handle) {
+    this.receiver_.$.bindHandle(handle);
+  }
+
+  addDevice(fakeDevice, info) {
+    let device = {
+      fakeDevice: fakeDevice,
+      guid: (this.nextGuid_++).toString(),
+      info: info,
+      receivers: [],
+    };
+    this.devices_.set(fakeDevice, device);
+    this.devicesByGuid_.set(device.guid, device);
+    if (this.client_)
+      this.client_.onDeviceAdded(fakeDeviceInitToDeviceInfo(device.guid, info));
+  }
+
+  async forgetDevice(guid) {
+    // Permissions are currently untestable through WPT.
+  }
+
+  removeDevice(fakeDevice) {
+    let device = this.devices_.get(fakeDevice);
+    if (!device)
+      throw new Error('Cannot remove unknown device.');
+
+    for (const receiver of device.receivers)
+      receiver.$.close();
+    this.devices_.delete(device.fakeDevice);
+    this.devicesByGuid_.delete(device.guid);
+    if (this.client_) {
+      this.client_.onDeviceRemoved(
+          fakeDeviceInitToDeviceInfo(device.guid, device.info));
+    }
+  }
+
+  removeAllDevices() {
+    this.devices_.forEach(device => {
+      for (const receiver of device.receivers)
+        receiver.$.close();
+      this.client_.onDeviceRemoved(
+          fakeDeviceInitToDeviceInfo(device.guid, device.info));
+    });
+    this.devices_.clear();
+    this.devicesByGuid_.clear();
+  }
+
+  getDevices() {
+    let devices = [];
+    this.devices_.forEach(device => {
+      devices.push(fakeDeviceInitToDeviceInfo(device.guid, device.info));
+    });
+    return Promise.resolve({ results: devices });
+  }
+
+  getDevice(guid, request) {
+    let retrievedDevice = this.devicesByGuid_.get(guid);
+    if (retrievedDevice) {
+      const receiver =
+          new mojom.UsbDeviceReceiver(new FakeDevice(retrievedDevice.info));
+      receiver.$.bindHandle(request.handle);
+      receiver.onConnectionError.addListener(() => {
+        if (retrievedDevice.fakeDevice.onclose)
+          retrievedDevice.fakeDevice.onclose();
+      });
+      retrievedDevice.receivers.push(receiver);
+    } else {
+      request.handle.close();
+    }
+  }
+
+  getPermission(options) {
+    return new Promise(resolve => {
+      if (navigator.usb.test.onrequestdevice) {
+        navigator.usb.test.onrequestdevice(
+            new USBDeviceRequestEvent(options, resolve));
+      } else {
+        resolve({ result: null });
+      }
+    });
+  }
+
+  setClient(client) {
+    this.client_ = client;
+  }
+}
+
+class USBDeviceRequestEvent {
+  constructor(options, resolve) {
+    this.filters = convertMojoDeviceFilters(options.filters);
+    this.exclusionFilters = convertMojoDeviceFilters(options.exclusionFilters);
+    this.resolveFunc_ = resolve;
+  }
+
+  respondWith(value) {
+    // Wait until |value| resolves (if it is a Promise). This function returns
+    // no value.
+    Promise.resolve(value).then(fakeDevice => {
+      let device = internal.webUsbService.devices_.get(fakeDevice);
+      let result = null;
+      if (device) {
+        result = fakeDeviceInitToDeviceInfo(device.guid, device.info);
+      }
+      this.resolveFunc_({ result: result });
+    }, () => {
+      this.resolveFunc_({ result: null });
+    });
+  }
+}
+
+// Unlike FakeDevice this class is exported to callers of USBTest.addFakeDevice.
+class FakeUSBDevice {
+  constructor() {
+    this.onclose = null;
+  }
+
+  disconnect() {
+    setTimeout(() => internal.webUsbService.removeDevice(this), 0);
+  }
+}
+
+class USBTest {
+  constructor() {
+    this.onrequestdevice = undefined;
+  }
+
+  async initialize() {
+    if (internal.initialized)
+      return;
+
+    // Be ready to handle 'ReadyForAttachment' message from child iframes.
+    if ('window' in self) {
+      getMessagePort(window);
+    }
+
+    mojom = await loadMojomDefinitions();
+    internal.webUsbService = new FakeWebUsbService();
+    internal.webUsbServiceInterceptor =
+        new MojoInterfaceInterceptor(mojom.WebUsbService.$interfaceName);
+    internal.webUsbServiceInterceptor.oninterfacerequest =
+        e => internal.webUsbService.addBinding(e.handle);
+    internal.webUsbServiceInterceptor.start();
+
+    // Wait for a call to GetDevices() to pass between the renderer and the
+    // mock in order to establish that everything is set up.
+    await navigator.usb.getDevices();
+    internal.initialized = true;
+  }
+
+  // Returns a promise that is resolved when the implementation of |usb| in the
+  // global scope for |context| is controlled by the current context.
+  attachToContext(context) {
+    if (!internal.initialized)
+      throw new Error('Call initialize() before attachToContext()');
+
+    let target = context.constructor.name === 'Worker' ? context : window;
+    return getMessagePort(target).then(() => {
+      return new Promise(resolve => {
+        internal.messagePort.onmessage = channelEvent => {
+          switch (channelEvent.data.type) {
+            case mojom.WebUsbService.$interfaceName:
+              internal.webUsbService.addBinding(channelEvent.data.handle);
+              break;
+            case 'Complete':
+              resolve();
+              break;
+          }
+        };
+        internal.messagePort.postMessage({
+          type: 'Attach',
+          interfaces: [
+            mojom.WebUsbService.$interfaceName,
+          ]
+        });
+      });
+    });
+  }
+
+  addFakeDevice(deviceInit) {
+    if (!internal.initialized)
+      throw new Error('Call initialize() before addFakeDevice().');
+
+    // |addDevice| and |removeDevice| are called in a setTimeout callback so
+    // that tests do not rely on the device being immediately available which
+    // may not be true for all implementations of this test API.
+    let fakeDevice = new FakeUSBDevice();
+    setTimeout(
+        () => internal.webUsbService.addDevice(fakeDevice, deviceInit), 0);
+    return fakeDevice;
+  }
+
+  reset() {
+    if (!internal.initialized)
+      throw new Error('Call initialize() before reset().');
+
+    // Reset the mocks in a setTimeout callback so that tests do not rely on
+    // the fact that this polyfill can do this synchronously.
+    return new Promise(resolve => {
+      setTimeout(() => {
+        if (internal.messagePort !== null)
+          internal.messagePort.close();
+        internal.messagePort = null;
+        internal.webUsbService.removeAllDevices();
+        resolve();
+      }, 0);
+    });
+  }
+}
+
+navigator.usb.test = new USBTest();
+
+})();
diff --git a/test/wpt/tests/resources/chromium/webusb-test.js.headers b/test/wpt/tests/resources/chromium/webusb-test.js.headers
new file mode 100644
index 0000000..6805c32
--- /dev/null
+++ b/test/wpt/tests/resources/chromium/webusb-test.js.headers
@@ -0,0 +1 @@
+Content-Type: text/javascript; charset=utf-8
diff --git a/test/wpt/tests/resources/chromium/webxr-test-math-helper.js b/test/wpt/tests/resources/chromium/webxr-test-math-helper.js
new file mode 100644
index 0000000..22c6c12
--- /dev/null
+++ b/test/wpt/tests/resources/chromium/webxr-test-math-helper.js
@@ -0,0 +1,298 @@
+'use strict';
+
+// Math helper - used mainly in hit test implementation done by webxr-test.js
+class XRMathHelper {
+  static toString(p) {
+    return "[" + p.x + "," + p.y + "," + p.z + "," + p.w + "]";
+  }
+
+  static transform_by_matrix(matrix, point) {
+    return {
+      x : matrix[0] * point.x + matrix[4] * point.y + matrix[8] * point.z + matrix[12] * point.w,
+      y : matrix[1] * point.x + matrix[5] * point.y + matrix[9] * point.z + matrix[13] * point.w,
+      z : matrix[2] * point.x + matrix[6] * point.y + matrix[10] * point.z + matrix[14] * point.w,
+      w : matrix[3] * point.x + matrix[7] * point.y + matrix[11] * point.z + matrix[15] * point.w,
+    };
+  }
+
+  static neg(p) {
+    return {x : -p.x, y : -p.y, z : -p.z, w : p.w};
+  }
+
+  static sub(lhs, rhs) {
+    // .w is treated here like an entity type, 1 signifies points, 0 signifies vectors.
+    // point - point, point - vector, vector - vector are ok, vector - point is not.
+    if (lhs.w != rhs.w && lhs.w == 0.0) {
+      throw new Error("vector - point not allowed: " + toString(lhs) + "-" + toString(rhs));
+    }
+
+    return {x : lhs.x - rhs.x, y : lhs.y - rhs.y, z : lhs.z - rhs.z, w : lhs.w - rhs.w};
+  }
+
+  static add(lhs, rhs) {
+    if (lhs.w == rhs.w && lhs.w == 1.0) {
+      throw new Error("point + point not allowed", p1, p2);
+    }
+
+    return {x : lhs.x + rhs.x, y : lhs.y + rhs.y, z : lhs.z + rhs.z, w : lhs.w + rhs.w};
+  }
+
+  static cross(lhs, rhs) {
+    if (lhs.w != 0.0 || rhs.w != 0.0) {
+      throw new Error("cross product not allowed: " + toString(lhs) + "x" + toString(rhs));
+    }
+
+    return {
+      x : lhs.y * rhs.z - lhs.z * rhs.y,
+      y : lhs.z * rhs.x - lhs.x * rhs.z,
+      z : lhs.x * rhs.y - lhs.y * rhs.x,
+      w : 0
+    };
+  }
+
+  static dot(lhs, rhs) {
+    if (lhs.w != 0 || rhs.w != 0) {
+      throw new Error("dot product not allowed: " + toString(lhs) + "x" + toString(rhs));
+    }
+
+    return lhs.x * rhs.x + lhs.y * rhs.y + lhs.z * rhs.z;
+  }
+
+  static mul(scalar, vector) {
+    if (vector.w != 0) {
+      throw new Error("scalar * vector not allowed", scalar, vector);
+    }
+
+    return {x : vector.x * scalar, y : vector.y * scalar, z : vector.z * scalar, w : vector.w};
+  }
+
+  static length(vector) {
+    return Math.sqrt(XRMathHelper.dot(vector, vector));
+  }
+
+  static normalize(vector) {
+    const l = XRMathHelper.length(vector);
+    return XRMathHelper.mul(1.0/l, vector);
+  }
+
+  // All |face|'s points and |point| must be co-planar.
+  static pointInFace(point, face) {
+    const normalize = XRMathHelper.normalize;
+    const sub = XRMathHelper.sub;
+    const length = XRMathHelper.length;
+    const cross = XRMathHelper.cross;
+
+    let onTheRight = null;
+    let previous_point = face[face.length - 1];
+
+    // |point| is in |face| if it's on the same side of all the edges.
+    for (let i = 0; i < face.length; ++i) {
+      const current_point = face[i];
+
+      const edge_direction = normalize(sub(current_point, previous_point));
+      const turn_direction = normalize(sub(point, current_point));
+
+      const sin_turn_angle = length(cross(edge_direction, turn_direction));
+
+      if (onTheRight == null) {
+        onTheRight = sin_turn_angle >= 0;
+      } else {
+        if (onTheRight && sin_turn_angle < 0) return false;
+        if (!onTheRight && sin_turn_angle > 0) return false;
+      }
+
+      previous_point = current_point;
+    }
+
+    return true;
+  }
+
+  static det2x2(m00, m01, m10, m11) {
+    return m00 * m11 - m01 * m10;
+  }
+
+  static det3x3(
+    m00, m01, m02,
+    m10, m11, m12,
+    m20, m21, m22
+  ){
+    const det2x2 = XRMathHelper.det2x2;
+
+    return    m00 * det2x2(m11, m12, m21, m22)
+            - m01 * det2x2(m10, m12, m20, m22)
+            + m02 * det2x2(m10, m11, m20, m21);
+  }
+
+  static det4x4(
+    m00, m01, m02, m03,
+    m10, m11, m12, m13,
+    m20, m21, m22, m23,
+    m30, m31, m32, m33
+  ) {
+    const det3x3 = XRMathHelper.det3x3;
+
+    return  m00 * det3x3(m11, m12, m13,
+                         m21, m22, m23,
+                         m31, m32, m33)
+          - m01 * det3x3(m10, m12, m13,
+                         m20, m22, m23,
+                         m30, m32, m33)
+          + m02 * det3x3(m10, m11, m13,
+                         m20, m21, m23,
+                         m30, m31, m33)
+          - m03 * det3x3(m10, m11, m12,
+                         m20, m21, m22,
+                         m30, m31, m32);
+  }
+
+  static inv2(m) {
+    // mij - i-th column, j-th row
+    const m00 = m[0],  m01 = m[1],  m02 = m[2],  m03 = m[3];
+    const m10 = m[4],  m11 = m[5],  m12 = m[6],  m13 = m[7];
+    const m20 = m[8],  m21 = m[9],  m22 = m[10], m23 = m[11];
+    const m30 = m[12], m31 = m[13], m32 = m[14], m33 = m[15];
+
+    const det = det4x4(
+      m00, m01, m02, m03,
+      m10, m11, m12, m13,
+      m20, m21, m22, m23,
+      m30, m31, m32, m33
+    );
+  }
+
+  static transpose(m) {
+    const result = Array(16);
+    for (let i = 0; i < 4; i++) {
+      for (let j = 0; j < 4; j++) {
+        result[i * 4 + j] = m[j * 4 + i];
+      }
+    }
+    return result;
+  }
+
+  // Inverts the matrix, ported from transformation_matrix.cc.
+  static inverse(m) {
+    const det3x3 = XRMathHelper.det3x3;
+
+    // mij - i-th column, j-th row
+    const m00 = m[0],  m01 = m[1],  m02 = m[2],  m03 = m[3];
+    const m10 = m[4],  m11 = m[5],  m12 = m[6],  m13 = m[7];
+    const m20 = m[8],  m21 = m[9],  m22 = m[10], m23 = m[11];
+    const m30 = m[12], m31 = m[13], m32 = m[14], m33 = m[15];
+
+    const det = XRMathHelper.det4x4(
+      m00, m01, m02, m03,
+      m10, m11, m12, m13,
+      m20, m21, m22, m23,
+      m30, m31, m32, m33
+    );
+
+    if (Math.abs(det) < 0.0001) {
+      return null;
+    }
+
+    const invDet = 1.0 / det;
+    // Calculate `comatrix * 1/det`:
+    const result2 = [
+      // First column (m0r):
+      invDet * det3x3(m11, m12, m13, m21, m22, m23, m32, m32, m33),
+      -invDet * det3x3(m10, m12, m13, m20, m22, m23, m30, m32, m33),
+      invDet * det3x3(m10, m11, m13, m20, m21, m23, m30, m31, m33),
+      -invDet * det3x3(m10, m11, m12, m20, m21, m22, m30, m31, m32),
+      // Second column (m1r):
+      -invDet * det3x3(m01, m02, m03, m21, m22, m23, m32, m32, m33),
+      invDet * det3x3(m00, m02, m03, m20, m22, m23, m30, m32, m33),
+      -invDet * det3x3(m00, m01, m03, m20, m21, m23, m30, m31, m33),
+      invDet * det3x3(m00, m01, m02, m20, m21, m22, m30, m31, m32),
+      // Third column (m2r):
+      invDet * det3x3(m01, m02, m03, m11, m12, m13, m31, m32, m33),
+      -invDet * det3x3(m00, m02, m03, m10, m12, m13, m30, m32, m33),
+      invDet * det3x3(m00, m01, m03, m10, m11, m13, m30, m31, m33),
+      -invDet * det3x3(m00, m01, m02, m10, m11, m12, m30, m31, m32),
+      // Fourth column (m3r):
+      -invDet * det3x3(m01, m02, m03, m11, m12, m13, m21, m22, m23),
+      invDet * det3x3(m00, m02, m03, m10, m12, m13, m20, m22, m23),
+      -invDet * det3x3(m00, m01, m03, m10, m11, m13, m20, m21, m23),
+      invDet * det3x3(m00, m01, m02, m10, m11, m12, m20, m21, m22),
+    ];
+
+    // Actual inverse is `1/det * transposed(comatrix)`:
+    return XRMathHelper.transpose(result2);
+  }
+
+  static mul4x4(m1, m2) {
+    if (m1 == null || m2 == null) {
+      return null;
+    }
+
+    const result = Array(16);
+
+    for (let row = 0; row < 4; row++) {
+      for (let col = 0; col < 4; col++) {
+        result[4 * col + row] = 0;
+        for(let i = 0; i < 4; i++) {
+          result[4 * col + row] += m1[4 * i + row] * m2[4 * col + i];
+        }
+      }
+    }
+
+    return result;
+  }
+
+  // Decomposes a matrix, with the assumption that the passed in matrix is
+  // a rigid transformation (i.e. position and rotation *only*!).
+  // The result is an object with `position` and `orientation` keys, which should
+  // be compatible with FakeXRRigidTransformInit.
+  // The implementation should match the behavior of gfx::Transform, but assumes
+  // that scale, skew & perspective are not present in the matrix so it could be
+  // simplified.
+  static decomposeRigidTransform(m) {
+    const m00 = m[0],  m01 = m[1],  m02 = m[2],  m03 = m[3];
+    const m10 = m[4],  m11 = m[5],  m12 = m[6],  m13 = m[7];
+    const m20 = m[8],  m21 = m[9],  m22 = m[10], m23 = m[11];
+    const m30 = m[12], m31 = m[13], m32 = m[14], m33 = m[15];
+
+    const position = [m30, m31, m32];
+    const orientation = [0, 0, 0, 0];
+
+    const trace = m00 + m11 + m22;
+    if (trace > 0) {
+      const S = Math.sqrt(trace + 1) * 2;
+      orientation[3] = 0.25 * S;
+      orientation[0] = (m12 - m21) / S;
+      orientation[1] = (m20 - m02) / S;
+      orientation[2] = (m01 - m10) / S;
+    } else if (m00 > m11 && m00 > m22) {
+      const S = Math.sqrt(1.0 + m00 - m11 - m22) * 2;
+      orientation[3] = (m12 - m21) / S;
+      orientation[0] = 0.25 * S;
+      orientation[1] = (m01 + m10) / S;
+      orientation[2] = (m20 + m02) / S;
+    } else if (m11 > m22) {
+      const S = Math.sqrt(1.0 + m11 - m00 - m22) * 2;
+      orientation[3] = (m20 - m02) / S;
+      orientation[0] = (m01 + m10) / S;
+      orientation[1] = 0.25 * S;
+      orientation[2] = (m12 + m21) / S;
+    } else {
+      const S = Math.sqrt(1.0 + m22 - m00 - m11) * 2;
+      orientation[3] = (m01 - m10) / S;
+      orientation[0] = (m20 + m02) / S;
+      orientation[1] = (m12 + m21) / S;
+      orientation[2] = 0.25 * S;
+    }
+
+    return { position, orientation };
+  }
+
+  static identity() {
+    return [
+      1, 0, 0, 0,
+      0, 1, 0, 0,
+      0, 0, 1, 0,
+      0, 0, 0, 1
+    ];
+  };
+}
+
+XRMathHelper.EPSILON = 0.001;
diff --git a/test/wpt/tests/resources/chromium/webxr-test-math-helper.js.headers b/test/wpt/tests/resources/chromium/webxr-test-math-helper.js.headers
new file mode 100644
index 0000000..6805c32
--- /dev/null
+++ b/test/wpt/tests/resources/chromium/webxr-test-math-helper.js.headers
@@ -0,0 +1 @@
+Content-Type: text/javascript; charset=utf-8
diff --git a/test/wpt/tests/resources/chromium/webxr-test.js b/test/wpt/tests/resources/chromium/webxr-test.js
new file mode 100644
index 0000000..c5eb1bd
--- /dev/null
+++ b/test/wpt/tests/resources/chromium/webxr-test.js
@@ -0,0 +1,2125 @@
+import * as vrMojom from '/gen/device/vr/public/mojom/vr_service.mojom.m.js';
+import * as xrSessionMojom from '/gen/device/vr/public/mojom/xr_session.mojom.m.js';
+import {GamepadHand, GamepadMapping} from '/gen/device/gamepad/public/mojom/gamepad.mojom.m.js';
+
+// This polyfill library implements the WebXR Test API as specified here:
+// https://github.com/immersive-web/webxr-test-api
+
+const defaultMojoFromFloor = {
+  matrix: [1, 0,     0, 0,
+           0, 1,     0, 0,
+           0, 0,     1, 0,
+           0, -1.65, 0, 1]
+};
+const default_stage_parameters = {
+  mojoFromFloor: defaultMojoFromFloor,
+  bounds: null
+};
+
+const default_framebuffer_scale = 0.7;
+
+function getMatrixFromTransform(transform) {
+  const x = transform.orientation[0];
+  const y = transform.orientation[1];
+  const z = transform.orientation[2];
+  const w = transform.orientation[3];
+
+  const m11 = 1.0 - 2.0 * (y * y + z * z);
+  const m21 = 2.0 * (x * y + z * w);
+  const m31 = 2.0 * (x * z - y * w);
+
+  const m12 = 2.0 * (x * y - z * w);
+  const m22 = 1.0 - 2.0 * (x * x + z * z);
+  const m32 = 2.0 * (y * z + x * w);
+
+  const m13 = 2.0 * (x * z + y * w);
+  const m23 = 2.0 * (y * z - x * w);
+  const m33 = 1.0 - 2.0 * (x * x + y * y);
+
+  const m14 = transform.position[0];
+  const m24 = transform.position[1];
+  const m34 = transform.position[2];
+
+  // Column-major linearized order is expected.
+  return [m11, m21, m31, 0,
+          m12, m22, m32, 0,
+          m13, m23, m33, 0,
+          m14, m24, m34, 1];
+}
+
+function getPoseFromTransform(transform) {
+  const [px, py, pz] = transform.position;
+  const [ox, oy, oz, ow] = transform.orientation;
+  return {
+    position: {x: px, y: py, z: pz},
+    orientation: {x: ox, y: oy, z: oz, w: ow},
+  };
+}
+
+function composeGFXTransform(fakeTransformInit) {
+  return {matrix: getMatrixFromTransform(fakeTransformInit)};
+}
+
+// Value equality for camera image init objects - they must contain `width` &
+// `height` properties and may contain `pixels` property.
+function isSameCameraImageInit(rhs, lhs) {
+  return lhs.width === rhs.width && lhs.height === rhs.height && lhs.pixels === rhs.pixels;
+}
+
+class ChromeXRTest {
+  constructor() {
+    this.mockVRService_ = new MockVRService();
+  }
+
+  // WebXR Test API
+  simulateDeviceConnection(init_params) {
+    return Promise.resolve(this.mockVRService_._addRuntime(init_params));
+  }
+
+  disconnectAllDevices() {
+    this.mockVRService_._removeAllRuntimes();
+    return Promise.resolve();
+  }
+
+  simulateUserActivation(callback) {
+    if (window.top !== window) {
+      // test_driver.click only works for the toplevel frame. This alternate
+      // Chrome-specific method is sufficient for starting an XR session in an
+      // iframe, and is used in platform-specific tests.
+      //
+      // TODO(https://github.com/web-platform-tests/wpt/issues/20282): use
+      // a cross-platform method if available.
+      xr_debug('simulateUserActivation', 'use eventSender');
+      document.addEventListener('click', callback);
+      eventSender.mouseMoveTo(0, 0);
+      eventSender.mouseDown();
+      eventSender.mouseUp();
+      document.removeEventListener('click', callback);
+      return;
+    }
+    const button = document.createElement('button');
+    button.textContent = 'click to continue test';
+    button.style.display = 'block';
+    button.style.fontSize = '20px';
+    button.style.padding = '10px';
+    button.onclick = () => {
+      callback();
+      document.body.removeChild(button);
+    };
+    document.body.appendChild(button);
+    test_driver.click(button);
+  }
+
+  // Helper method leveraged by chrome-specific setups.
+  Debug(name, msg) {
+    console.log(new Date().toISOString() + ' DEBUG[' + name + '] ' + msg);
+  }
+}
+
+// Mocking class definitions
+
+// Mock service implements the VRService mojo interface.
+class MockVRService {
+  constructor() {
+    this.receiver_ = new vrMojom.VRServiceReceiver(this);
+    this.runtimes_ = [];
+
+    this.interceptor_ =
+        new MojoInterfaceInterceptor(vrMojom.VRService.$interfaceName);
+    this.interceptor_.oninterfacerequest =
+        e => this.receiver_.$.bindHandle(e.handle);
+    this.interceptor_.start();
+  }
+
+  // WebXR Test API Implementation Helpers
+  _addRuntime(fakeDeviceInit) {
+    const runtime = new MockRuntime(fakeDeviceInit, this);
+    this.runtimes_.push(runtime);
+
+    if (this.client_) {
+      this.client_.onDeviceChanged();
+    }
+
+    return runtime;
+  }
+
+  _removeAllRuntimes() {
+    if (this.client_) {
+      this.client_.onDeviceChanged();
+    }
+
+    this.runtimes_ = [];
+  }
+
+  _removeRuntime(device) {
+    const index = this.runtimes_.indexOf(device);
+    if (index >= 0) {
+      this.runtimes_.splice(index, 1);
+      if (this.client_) {
+        this.client_.onDeviceChanged();
+      }
+    }
+  }
+
+  // VRService overrides
+  setClient(client) {
+    if (this.client_) {
+      throw new Error("setClient should only be called once");
+    }
+
+    this.client_ = client;
+  }
+
+  requestSession(sessionOptions) {
+    const requests = [];
+    // Request a session from all the runtimes.
+    for (let i = 0; i < this.runtimes_.length; i++) {
+      requests[i] = this.runtimes_[i]._requestRuntimeSession(sessionOptions);
+    }
+
+    return Promise.all(requests).then((results) => {
+      // Find and return the first successful result.
+      for (let i = 0; i < results.length; i++) {
+        if (results[i].session) {
+          // Construct a dummy metrics recorder
+          const metricsRecorderPtr = new vrMojom.XRSessionMetricsRecorderRemote();
+          metricsRecorderPtr.$.bindNewPipeAndPassReceiver().handle.close();
+
+          const success = {
+            session: results[i].session,
+            metricsRecorder: metricsRecorderPtr,
+          };
+
+          return {result: {success}};
+        }
+      }
+
+      // If there were no successful results, returns a null session.
+      return {
+        result: {failureReason: vrMojom.RequestSessionError.NO_RUNTIME_FOUND}
+      };
+    });
+  }
+
+  supportsSession(sessionOptions) {
+    const requests = [];
+    // Check supports on all the runtimes.
+    for (let i = 0; i < this.runtimes_.length; i++) {
+      requests[i] = this.runtimes_[i]._runtimeSupportsSession(sessionOptions);
+    }
+
+    return Promise.all(requests).then((results) => {
+      // Find and return the first successful result.
+      for (let i = 0; i < results.length; i++) {
+        if (results[i].supportsSession) {
+          return results[i];
+        }
+      }
+
+      // If there were no successful results, returns false.
+      return {supportsSession: false};
+    });
+  }
+
+  exitPresent() {
+    return Promise.resolve();
+  }
+
+  setFramesThrottled(throttled) {
+    this.setFramesThrottledImpl(throttled);
+  }
+
+  // We cannot override the mojom interceptors via the prototype; so this method
+  // and the above indirection exist to allow overrides by internal code.
+  setFramesThrottledImpl(throttled) {}
+
+  // Only handles asynchronous calls to makeXrCompatible. Synchronous calls are
+  // not supported in Javascript.
+  makeXrCompatible() {
+    if (this.runtimes_.length == 0) {
+      return {
+        xrCompatibleResult: vrMojom.XrCompatibleResult.kNoDeviceAvailable
+      };
+    }
+    return {xrCompatibleResult: vrMojom.XrCompatibleResult.kAlreadyCompatible};
+  }
+}
+
+class FakeXRAnchorController {
+  constructor() {
+    // Private properties.
+    this.device_ = null;
+    this.id_ = null;
+    this.dirty_ = true;
+
+    // Properties backing up public attributes / methods.
+    this.deleted_ = false;
+    this.paused_ = false;
+    this.anchorOrigin_ = XRMathHelper.identity();
+  }
+
+  // WebXR Test API (Anchors Extension)
+  get deleted() {
+    return this.deleted_;
+  }
+
+  pauseTracking() {
+    if(!this.paused_) {
+      this.paused_ = true;
+      this.dirty_ = true;
+    }
+  }
+
+  resumeTracking() {
+    if(this.paused_) {
+      this.paused_ = false;
+      this.dirty_ = true;
+    }
+  }
+
+  stopTracking() {
+    if(!this.deleted_) {
+      this.device_._deleteAnchorController(this.id_);
+
+      this.deleted_ = true;
+      this.dirty_ = true;
+    }
+  }
+
+  setAnchorOrigin(anchorOrigin) {
+    this.anchorOrigin_ = getMatrixFromTransform(anchorOrigin);
+    this.dirty_ = true;
+  }
+
+  // Internal implementation:
+  set id(value) {
+    this.id_ = value;
+  }
+
+  set device(value) {
+    this.device_ = value;
+  }
+
+  get dirty() {
+    return this.dirty_;
+  }
+
+  get paused() {
+    return this.paused_;
+  }
+
+  _markProcessed() {
+    this.dirty_ = false;
+  }
+
+  _getAnchorOrigin() {
+    return this.anchorOrigin_;
+  }
+}
+
+// Implements XRFrameDataProvider and XRPresentationProvider. Maintains a mock
+// for XRPresentationProvider. Implements FakeXRDevice test API.
+class MockRuntime {
+  // Mapping from string feature names to the corresponding mojo types.
+  // This is exposed as a member for extensibility.
+  static _featureToMojoMap = {
+    'viewer': xrSessionMojom.XRSessionFeature.REF_SPACE_VIEWER,
+    'local': xrSessionMojom.XRSessionFeature.REF_SPACE_LOCAL,
+    'local-floor': xrSessionMojom.XRSessionFeature.REF_SPACE_LOCAL_FLOOR,
+    'bounded-floor': xrSessionMojom.XRSessionFeature.REF_SPACE_BOUNDED_FLOOR,
+    'unbounded': xrSessionMojom.XRSessionFeature.REF_SPACE_UNBOUNDED,
+    'hit-test': xrSessionMojom.XRSessionFeature.HIT_TEST,
+    'dom-overlay': xrSessionMojom.XRSessionFeature.DOM_OVERLAY,
+    'light-estimation': xrSessionMojom.XRSessionFeature.LIGHT_ESTIMATION,
+    'anchors': xrSessionMojom.XRSessionFeature.ANCHORS,
+    'depth-sensing': xrSessionMojom.XRSessionFeature.DEPTH,
+    'secondary-views': xrSessionMojom.XRSessionFeature.SECONDARY_VIEWS,
+    'camera-access': xrSessionMojom.XRSessionFeature.CAMERA_ACCESS,
+    'layers': xrSessionMojom.XRSessionFeature.LAYERS,
+  };
+
+  static _sessionModeToMojoMap = {
+    "inline": xrSessionMojom.XRSessionMode.kInline,
+    "immersive-vr": xrSessionMojom.XRSessionMode.kImmersiveVr,
+    "immersive-ar": xrSessionMojom.XRSessionMode.kImmersiveAr,
+  };
+
+  static _environmentBlendModeToMojoMap = {
+    "opaque": vrMojom.XREnvironmentBlendMode.kOpaque,
+    "alpha-blend": vrMojom.XREnvironmentBlendMode.kAlphaBlend,
+    "additive": vrMojom.XREnvironmentBlendMode.kAdditive,
+  };
+
+  static _interactionModeToMojoMap = {
+    "screen-space": vrMojom.XRInteractionMode.kScreenSpace,
+    "world-space": vrMojom.XRInteractionMode.kWorldSpace,
+  };
+
+  constructor(fakeDeviceInit, service) {
+    this.sessionClient_ = null;
+    this.presentation_provider_ = new MockXRPresentationProvider();
+
+    this.pose_ = null;
+    this.next_frame_id_ = 0;
+    this.bounds_ = null;
+    this.send_mojo_space_reset_ = false;
+    this.stageParameters_ = null;
+    this.stageParametersId_ = 1;
+
+    this.service_ = service;
+
+    this.framesOfReference = {};
+
+    this.input_sources_ = new Map();
+    this.next_input_source_index_ = 1;
+
+    // Currently active hit test subscriptons.
+    this.hitTestSubscriptions_ = new Map();
+    // Currently active transient hit test subscriptions.
+    this.transientHitTestSubscriptions_ = new Map();
+    // ID of the next subscription to be assigned.
+    this.next_hit_test_id_ = 1n;
+
+    this.anchor_controllers_ = new Map();
+    // ID of the next anchor to be assigned.
+    this.next_anchor_id_ = 1n;
+    // Anchor creation callback (initially null, can be set by tests).
+    this.anchor_creation_callback_ = null;
+
+    this.depthSensingData_ = null;
+    this.depthSensingDataDirty_ = false;
+
+    let supportedModes = [];
+    if (fakeDeviceInit.supportedModes) {
+      supportedModes = fakeDeviceInit.supportedModes.slice();
+      if (fakeDeviceInit.supportedModes.length === 0) {
+        supportedModes = ["inline"];
+      }
+    } else {
+      // Back-compat mode.
+      console.warn("Please use `supportedModes` to signal which modes are supported by this device.");
+      if (fakeDeviceInit.supportsImmersive == null) {
+        throw new TypeError("'supportsImmersive' must be set");
+      }
+
+      supportedModes = ["inline"];
+      if (fakeDeviceInit.supportsImmersive) {
+        supportedModes.push("immersive-vr");
+      }
+    }
+
+    this.supportedModes_ = this._convertModesToEnum(supportedModes);
+    if (this.supportedModes_.length == 0) {
+      console.error("Device has empty supported modes array!");
+      throw new InvalidStateError();
+    }
+
+    if (fakeDeviceInit.viewerOrigin != null) {
+      this.setViewerOrigin(fakeDeviceInit.viewerOrigin);
+    }
+
+    if (fakeDeviceInit.floorOrigin != null) {
+      this.setFloorOrigin(fakeDeviceInit.floorOrigin);
+    }
+
+    if (fakeDeviceInit.world) {
+      this.setWorld(fakeDeviceInit.world);
+    }
+
+    if (fakeDeviceInit.depthSensingData) {
+      this.setDepthSensingData(fakeDeviceInit.depthSensingData);
+    }
+
+    this.defaultFramebufferScale_ = default_framebuffer_scale;
+    this.enviromentBlendMode_ = this._convertBlendModeToEnum(fakeDeviceInit.environmentBlendMode);
+    this.interactionMode_ = this._convertInteractionModeToEnum(fakeDeviceInit.interactionMode);
+
+    // This appropriately handles if the coordinates are null
+    this.setBoundsGeometry(fakeDeviceInit.boundsCoordinates);
+
+    this.setViews(fakeDeviceInit.views, fakeDeviceInit.secondaryViews);
+
+    // Need to support webVR which doesn't have a notion of features
+    this._setFeatures(fakeDeviceInit.supportedFeatures || []);
+  }
+
+  // WebXR Test API
+  setViews(primaryViews, secondaryViews) {
+    this.cameraImage_ = null;
+    this.primaryViews_ = [];
+    this.secondaryViews_ = [];
+    let xOffset = 0;
+    if (primaryViews) {
+      this.primaryViews_ = [];
+      xOffset = this._setViews(primaryViews, xOffset, this.primaryViews_);
+      const cameraImage = this._findCameraImage(primaryViews);
+
+      if (cameraImage) {
+        this.cameraImage_ = cameraImage;
+      }
+    }
+
+    if (secondaryViews) {
+      this.secondaryViews_ = [];
+      this._setViews(secondaryViews, xOffset, this.secondaryViews_);
+      const cameraImage = this._findCameraImage(secondaryViews);
+
+      if (cameraImage) {
+        if (!isSameCameraImageInit(this.cameraImage_, cameraImage)) {
+          throw new Error("If present, camera resolutions on each view must match each other!"
+                          + " Secondary views' camera doesn't match primary views.");
+        }
+
+        this.cameraImage_ = cameraImage;
+      }
+    }
+  }
+
+  disconnect() {
+    this.service_._removeRuntime(this);
+    this.presentation_provider_._close();
+    if (this.sessionClient_) {
+      this.sessionClient_.$.close();
+      this.sessionClient_ = null;
+    }
+
+    return Promise.resolve();
+  }
+
+  setViewerOrigin(origin, emulatedPosition = false) {
+    const p = origin.position;
+    const q = origin.orientation;
+    this.pose_ = {
+      orientation: { x: q[0], y: q[1], z: q[2], w: q[3] },
+      position: { x: p[0], y: p[1], z: p[2] },
+      emulatedPosition: emulatedPosition,
+      angularVelocity: null,
+      linearVelocity: null,
+      angularAcceleration: null,
+      linearAcceleration: null,
+      inputState: null,
+      poseIndex: 0
+    };
+  }
+
+  clearViewerOrigin() {
+    this.pose_ = null;
+  }
+
+  setFloorOrigin(floorOrigin) {
+    if (!this.stageParameters_) {
+      this.stageParameters_ = default_stage_parameters;
+      this.stageParameters_.bounds = this.bounds_;
+    }
+
+    // floorOrigin is passed in as mojoFromFloor.
+    this.stageParameters_.mojoFromFloor =
+        {matrix: getMatrixFromTransform(floorOrigin)};
+
+    this._onStageParametersUpdated();
+  }
+
+  clearFloorOrigin() {
+    if (this.stageParameters_) {
+      this.stageParameters_ = null;
+      this._onStageParametersUpdated();
+    }
+  }
+
+  setBoundsGeometry(bounds) {
+    if (bounds == null) {
+      this.bounds_ = null;
+    } else if (bounds.length < 3) {
+      throw new Error("Bounds must have a length of at least 3");
+    } else {
+      this.bounds_ = bounds;
+    }
+
+    // We can only set bounds if we have stageParameters set; otherwise, we
+    // don't know the transform from local space to bounds space.
+    // We'll cache the bounds so that they can be set in the future if the
+    // floorLevel transform is set, but we won't update them just yet.
+    if (this.stageParameters_) {
+      this.stageParameters_.bounds = this.bounds_;
+      this._onStageParametersUpdated();
+    }
+  }
+
+  simulateResetPose() {
+    this.send_mojo_space_reset_ = true;
+  }
+
+  simulateVisibilityChange(visibilityState) {
+    let mojoState = null;
+    switch (visibilityState) {
+      case "visible":
+        mojoState = vrMojom.XRVisibilityState.VISIBLE;
+        break;
+      case "visible-blurred":
+        mojoState = vrMojom.XRVisibilityState.VISIBLE_BLURRED;
+        break;
+      case "hidden":
+        mojoState = vrMojom.XRVisibilityState.HIDDEN;
+        break;
+    }
+    if (mojoState && this.sessionClient_) {
+      this.sessionClient_.onVisibilityStateChanged(mojoState);
+    }
+  }
+
+  simulateInputSourceConnection(fakeInputSourceInit) {
+    const index = this.next_input_source_index_;
+    this.next_input_source_index_++;
+
+    const source = new MockXRInputSource(fakeInputSourceInit, index, this);
+    this.input_sources_.set(index, source);
+    return source;
+  }
+
+  // WebXR Test API Hit Test extensions
+  setWorld(world) {
+    this.world_ = world;
+  }
+
+  clearWorld() {
+    this.world_ = null;
+  }
+
+  // WebXR Test API Anchor extensions
+  setAnchorCreationCallback(callback) {
+    this.anchor_creation_callback_ = callback;
+  }
+
+  setHitTestSourceCreationCallback(callback) {
+    this.hit_test_source_creation_callback_ = callback;
+  }
+
+  // WebXR Test API Lighting estimation extensions
+  setLightEstimate(fakeXrLightEstimateInit) {
+    if (!fakeXrLightEstimateInit.sphericalHarmonicsCoefficients) {
+      throw new TypeError("sphericalHarmonicsCoefficients must be set");
+    }
+
+    if (fakeXrLightEstimateInit.sphericalHarmonicsCoefficients.length != 27) {
+      throw new TypeError("Must supply all 27 sphericalHarmonicsCoefficients");
+    }
+
+    if (fakeXrLightEstimateInit.primaryLightDirection && fakeXrLightEstimateInit.primaryLightDirection.w != 0) {
+      throw new TypeError("W component of primaryLightDirection must be 0");
+    }
+
+    if (fakeXrLightEstimateInit.primaryLightIntensity && fakeXrLightEstimateInit.primaryLightIntensity.w != 1) {
+      throw new TypeError("W component of primaryLightIntensity must be 1");
+    }
+
+    // If the primaryLightDirection or primaryLightIntensity aren't set, we need to set them
+    // to the defaults that the spec expects. ArCore will either give us everything or nothing,
+    // so these aren't nullable on the mojom.
+    if (!fakeXrLightEstimateInit.primaryLightDirection) {
+      fakeXrLightEstimateInit.primaryLightDirection = { x: 0.0, y: 1.0, z: 0.0, w: 0.0 };
+    }
+
+    if (!fakeXrLightEstimateInit.primaryLightIntensity) {
+      fakeXrLightEstimateInit.primaryLightIntensity = { x: 0.0, y: 0.0, z: 0.0, w: 1.0 };
+    }
+
+    let c = fakeXrLightEstimateInit.sphericalHarmonicsCoefficients;
+
+    this.light_estimate_ = {
+      lightProbe: {
+        // XRSphereicalHarmonics
+        sphericalHarmonics: {
+          coefficients: [
+            { red: c[0],  green: c[1],  blue: c[2] },
+            { red: c[3],  green: c[4],  blue: c[5] },
+            { red: c[6],  green: c[7],  blue: c[8] },
+            { red: c[9],  green: c[10], blue: c[11] },
+            { red: c[12], green: c[13], blue: c[14] },
+            { red: c[15], green: c[16], blue: c[17] },
+            { red: c[18], green: c[19], blue: c[20] },
+            { red: c[21], green: c[22], blue: c[23] },
+            { red: c[24], green: c[25], blue: c[26] }
+          ]
+        },
+        // Vector3dF
+        mainLightDirection: {
+          x: fakeXrLightEstimateInit.primaryLightDirection.x,
+          y: fakeXrLightEstimateInit.primaryLightDirection.y,
+          z: fakeXrLightEstimateInit.primaryLightDirection.z
+        },
+        // RgbTupleF32
+        mainLightIntensity: {
+          red:   fakeXrLightEstimateInit.primaryLightIntensity.x,
+          green: fakeXrLightEstimateInit.primaryLightIntensity.y,
+          blue:  fakeXrLightEstimateInit.primaryLightIntensity.z
+        }
+      }
+    }
+  }
+
+  // WebXR Test API depth Sensing Extensions
+  setDepthSensingData(depthSensingData) {
+    for(const key of ["depthData", "normDepthBufferFromNormView", "rawValueToMeters", "width", "height"]) {
+      if(!(key in depthSensingData)) {
+        throw new TypeError("Required key not present. Key: " + key);
+      }
+    }
+
+    if(depthSensingData.depthData != null) {
+      // Create new object w/ properties based on the depthSensingData, but
+      // convert the FakeXRRigidTransformInit into a transformation matrix object.
+      this.depthSensingData_ = Object.assign({},
+        depthSensingData, {
+          normDepthBufferFromNormView: composeGFXTransform(depthSensingData.normDepthBufferFromNormView),
+        });
+    } else {
+      throw new TypeError("`depthData` is not set");
+    }
+
+    this.depthSensingDataDirty_ = true;
+  }
+
+  clearDepthSensingData() {
+    this.depthSensingData_ = null;
+    this.depthSensingDataDirty_ = true;
+  }
+
+  // Internal Implementation/Helper Methods
+  _convertModeToEnum(sessionMode) {
+    if (sessionMode in MockRuntime._sessionModeToMojoMap) {
+      return MockRuntime._sessionModeToMojoMap[sessionMode];
+    }
+
+    throw new TypeError("Unrecognized value for XRSessionMode enum: " + sessionMode);
+  }
+
+  _convertModesToEnum(sessionModes) {
+    return sessionModes.map(mode => this._convertModeToEnum(mode));
+  }
+
+  _convertBlendModeToEnum(blendMode) {
+    if (blendMode in MockRuntime._environmentBlendModeToMojoMap) {
+      return MockRuntime._environmentBlendModeToMojoMap[blendMode];
+    } else {
+      if (this.supportedModes_.includes(xrSessionMojom.XRSessionMode.kImmersiveAr)) {
+        return vrMojom.XREnvironmentBlendMode.kAdditive;
+      } else if (this.supportedModes_.includes(
+        xrSessionMojom.XRSessionMode.kImmersiveVr)) {
+        return vrMojom.XREnvironmentBlendMode.kOpaque;
+      }
+    }
+  }
+
+  _convertInteractionModeToEnum(interactionMode) {
+    if (interactionMode in MockRuntime._interactionModeToMojoMap) {
+      return MockRuntime._interactionModeToMojoMap[interactionMode];
+    } else {
+      return vrMojom.XRInteractionMode.kWorldSpace;
+    }
+  }
+
+  _setViews(deviceViews, xOffset, views) {
+    for (let i = 0; i < deviceViews.length; i++) {
+      views[i] = this._getView(deviceViews[i], xOffset);
+      xOffset += deviceViews[i].resolution.width;
+    }
+
+    return xOffset;
+  }
+
+  _findCameraImage(views) {
+    const viewWithCamera = views.find(view => view.cameraImageInit);
+    if (viewWithCamera) {
+      //If we have one view with a camera resolution, all views should have the same camera resolution.
+      const allViewsHaveSameCamera = views.every(
+        view => isSameCameraImageInit(view.cameraImageInit, viewWithCamera.cameraImageInit));
+
+      if (!allViewsHaveSameCamera) {
+        throw new Error("If present, camera resolutions on each view must match each other!");
+      }
+
+      return viewWithCamera.cameraImageInit;
+    }
+
+    return null;
+  }
+
+  _onStageParametersUpdated() {
+    // Indicate for the frame loop that the stage parameters have been updated.
+    this.stageParametersId_++;
+  }
+
+  _getDefaultViews() {
+    if (this.primaryViews_) {
+      return this.primaryViews_;
+    }
+
+    const viewport_size = 20;
+    return [{
+        eye: vrMojom.XREye.kLeft,
+        fieldOfView: {
+          upDegrees: 48.316,
+          downDegrees: 50.099,
+          leftDegrees: 50.899,
+          rightDegrees: 35.197
+        },
+        mojoFromView: this._getMojoFromViewerWithOffset(composeGFXTransform({
+          position: [-0.032, 0, 0],
+          orientation: [0, 0, 0, 1]
+        })),
+        viewport: { x: 0, y: 0, width: viewport_size, height: viewport_size }
+      },
+      {
+        eye: vrMojom.XREye.kRight,
+        fieldOfView: {
+          upDegrees: 48.316,
+          downDegrees: 50.099,
+          leftDegrees: 50.899,
+          rightDegrees: 35.197
+        },
+        mojoFromView: this._getMojoFromViewerWithOffset(composeGFXTransform({
+          position: [0.032, 0, 0],
+          orientation: [0, 0, 0, 1]
+        })),
+        viewport: { x: viewport_size, y: 0, width: viewport_size, height: viewport_size }
+      }];
+  }
+
+  // This function converts between the matrix provided by the WebXR test API
+  // and the internal data representation.
+  _getView(fakeXRViewInit, xOffset) {
+    let fov = null;
+
+    if (fakeXRViewInit.fieldOfView) {
+      fov = {
+        upDegrees: fakeXRViewInit.fieldOfView.upDegrees,
+        downDegrees: fakeXRViewInit.fieldOfView.downDegrees,
+        leftDegrees: fakeXRViewInit.fieldOfView.leftDegrees,
+        rightDegrees: fakeXRViewInit.fieldOfView.rightDegrees
+      };
+    } else {
+      const m = fakeXRViewInit.projectionMatrix;
+
+      function toDegrees(tan) {
+        return Math.atan(tan) * 180 / Math.PI;
+      }
+
+      const leftTan = (1 - m[8]) / m[0];
+      const rightTan = (1 + m[8]) / m[0];
+      const upTan = (1 + m[9]) / m[5];
+      const downTan = (1 - m[9]) / m[5];
+
+      fov = {
+        upDegrees: toDegrees(upTan),
+        downDegrees: toDegrees(downTan),
+        leftDegrees: toDegrees(leftTan),
+        rightDegrees: toDegrees(rightTan)
+      };
+    }
+
+    let viewEye = vrMojom.XREye.kNone;
+    // The eye passed in corresponds to the values in the WebXR spec, which are
+    // the strings "none", "left", and "right". They should be converted to the
+    // corresponding values of XREye in vr_service.mojom.
+    switch(fakeXRViewInit.eye) {
+      case "none":
+        viewEye = vrMojom.XREye.kNone;
+        break;
+      case "left":
+        viewEye = vrMojom.XREye.kLeft;
+        break;
+      case "right":
+        viewEye = vrMojom.XREye.kRight;
+        break;
+    }
+
+    return {
+      eye: viewEye,
+      fieldOfView: fov,
+      mojoFromView: this._getMojoFromViewerWithOffset(composeGFXTransform(fakeXRViewInit.viewOffset)),
+      viewport: {
+        x: xOffset,
+        y: 0,
+        width: fakeXRViewInit.resolution.width,
+        height: fakeXRViewInit.resolution.height
+      },
+      isFirstPersonObserver: fakeXRViewInit.isFirstPersonObserver ? true : false,
+      viewOffset: composeGFXTransform(fakeXRViewInit.viewOffset)
+    };
+  }
+
+  _setFeatures(supportedFeatures) {
+    function convertFeatureToMojom(feature) {
+      if (feature in MockRuntime._featureToMojoMap) {
+        return MockRuntime._featureToMojoMap[feature];
+      } else {
+        return xrSessionMojom.XRSessionFeature.INVALID;
+      }
+    }
+
+    this.supportedFeatures_ = [];
+
+    for (let i = 0; i < supportedFeatures.length; i++) {
+      const feature = convertFeatureToMojom(supportedFeatures[i]);
+      if (feature !== xrSessionMojom.XRSessionFeature.INVALID) {
+        this.supportedFeatures_.push(feature);
+      }
+    }
+  }
+
+  // These methods are intended to be used by MockXRInputSource only.
+  _addInputSource(source) {
+    if (!this.input_sources_.has(source.source_id_)) {
+      this.input_sources_.set(source.source_id_, source);
+    }
+  }
+
+  _removeInputSource(source) {
+    this.input_sources_.delete(source.source_id_);
+  }
+
+  // These methods are intended to be used by FakeXRAnchorController only.
+  _deleteAnchorController(controllerId) {
+    this.anchor_controllers_.delete(controllerId);
+  }
+
+  // Extension point for non-standard modules.
+  _injectAdditionalFrameData(options, frameData) {
+  }
+
+  // Mojo function implementations.
+
+  // XRFrameDataProvider implementation.
+  getFrameData(options) {
+    return new Promise((resolve) => {
+
+      const populatePose = () => {
+        const mojo_space_reset = this.send_mojo_space_reset_;
+        this.send_mojo_space_reset_ = false;
+
+        if (this.pose_) {
+          this.pose_.poseIndex++;
+        }
+
+        // Setting the input_state to null tests a slightly different path than
+        // the browser tests where if the last input source is removed, the device
+        // code always sends up an empty array, but it's also valid mojom to send
+        // up a null array.
+        let input_state = null;
+        if (this.input_sources_.size > 0) {
+          input_state = [];
+          for (const input_source of this.input_sources_.values()) {
+            input_state.push(input_source._getInputSourceState());
+          }
+        }
+
+        let frame_views = this.primaryViews_;
+        for (let i = 0; i < this.primaryViews_.length; i++) {
+          this.primaryViews_[i].mojoFromView =
+            this._getMojoFromViewerWithOffset(this.primaryViews_[i].viewOffset);
+        }
+        if (this.enabledFeatures_.includes(xrSessionMojom.XRSessionFeature.SECONDARY_VIEWS)) {
+          for (let i = 0; i < this.secondaryViews_.length; i++) {
+            this.secondaryViews_[i].mojoFromView =
+              this._getMojoFromViewerWithOffset(this.secondaryViews_[i].viewOffset);
+          }
+
+          frame_views = frame_views.concat(this.secondaryViews_);
+        }
+
+        const frameData = {
+          mojoFromViewer: this.pose_,
+          views: frame_views,
+          mojoSpaceReset: mojo_space_reset,
+          inputState: input_state,
+          timeDelta: {
+            // window.performance.now() is in milliseconds, so convert to microseconds.
+            microseconds: BigInt(Math.floor(window.performance.now() * 1000)),
+          },
+          frameId: this.next_frame_id_,
+          bufferHolder: null,
+          cameraImageSize: this.cameraImage_ ? {
+            width: this.cameraImage_.width,
+            height: this.cameraImage_.height
+          } : null,
+          renderingTimeRatio: 0,
+          stageParameters: this.stageParameters_,
+          stageParametersId: this.stageParametersId_,
+          lightEstimationData: this.light_estimate_
+        };
+
+        this.next_frame_id_++;
+
+        this._calculateHitTestResults(frameData);
+
+        this._calculateAnchorInformation(frameData);
+
+        this._calculateDepthInformation(frameData);
+
+        this._injectAdditionalFrameData(options, frameData);
+
+        resolve({frameData});
+      };
+
+      if(this.sessionOptions_.mode == xrSessionMojom.XRSessionMode.kInline) {
+        // Inline sessions should not have a delay introduced since it causes them
+        // to miss a vsync blink-side and delays propagation of changes that happened
+        // within a rAFcb by one frame (e.g. setViewerOrigin() calls would take 2 frames
+        // to propagate).
+        populatePose();
+      } else {
+        // For immerive sessions, add additional delay to allow for anchor creation
+        // promises to run.
+        setTimeout(populatePose, 3);  // note: according to MDN, the timeout is not exact
+      }
+    });
+  }
+
+  getEnvironmentIntegrationProvider(environmentProviderRequest) {
+    if (this.environmentProviderReceiver_) {
+      this.environmentProviderReceiver_.$.close();
+    }
+    this.environmentProviderReceiver_ =
+        new vrMojom.XREnvironmentIntegrationProviderReceiver(this);
+    this.environmentProviderReceiver_.$.bindHandle(
+        environmentProviderRequest.handle);
+  }
+
+  // XREnvironmentIntegrationProvider implementation:
+  subscribeToHitTest(nativeOriginInformation, entityTypes, ray) {
+    if (!this.supportedModes_.includes(xrSessionMojom.XRSessionMode.kImmersiveAr)) {
+      // Reject outside of AR.
+      return Promise.resolve({
+        result : vrMojom.SubscribeToHitTestResult.FAILURE_GENERIC,
+        subscriptionId : 0n
+      });
+    }
+
+    if (!this._nativeOriginKnown(nativeOriginInformation)) {
+      return Promise.resolve({
+        result : vrMojom.SubscribeToHitTestResult.FAILURE_GENERIC,
+        subscriptionId : 0n
+      });
+    }
+
+    // Reserve the id for hit test source:
+    const id = this.next_hit_test_id_++;
+    const hitTestParameters = { isTransient: false, profileName: null };
+    const controller = new FakeXRHitTestSourceController(id);
+
+
+    return this._shouldHitTestSourceCreationSucceed(hitTestParameters, controller)
+      .then((succeeded) => {
+        if(succeeded) {
+          // Store the subscription information as-is (including controller):
+          this.hitTestSubscriptions_.set(id, { nativeOriginInformation, entityTypes, ray, controller });
+
+          return Promise.resolve({
+            result : vrMojom.SubscribeToHitTestResult.SUCCESS,
+            subscriptionId : id
+          });
+        } else {
+          return Promise.resolve({
+            result : vrMojom.SubscribeToHitTestResult.FAILURE_GENERIC,
+            subscriptionId : 0n
+          });
+        }
+      });
+  }
+
+  subscribeToHitTestForTransientInput(profileName, entityTypes, ray){
+    if (!this.supportedModes_.includes(xrSessionMojom.XRSessionMode.kImmersiveAr)) {
+      // Reject outside of AR.
+      return Promise.resolve({
+        result : vrMojom.SubscribeToHitTestResult.FAILURE_GENERIC,
+        subscriptionId : 0n
+      });
+    }
+
+    const id = this.next_hit_test_id_++;
+    const hitTestParameters = { isTransient: true, profileName: profileName };
+    const controller = new FakeXRHitTestSourceController(id);
+
+    // Check if we have hit test source creation callback.
+    // If yes, ask it if the hit test source creation should succeed.
+    // If no, for back-compat, assume the hit test source creation succeeded.
+    return this._shouldHitTestSourceCreationSucceed(hitTestParameters, controller)
+      .then((succeeded) => {
+        if(succeeded) {
+          // Store the subscription information as-is (including controller):
+          this.transientHitTestSubscriptions_.set(id, { profileName, entityTypes, ray, controller });
+
+          return Promise.resolve({
+            result : vrMojom.SubscribeToHitTestResult.SUCCESS,
+            subscriptionId : id
+          });
+        } else {
+          return Promise.resolve({
+            result : vrMojom.SubscribeToHitTestResult.FAILURE_GENERIC,
+            subscriptionId : 0n
+          });
+        }
+      });
+  }
+
+  unsubscribeFromHitTest(subscriptionId) {
+    let controller = null;
+    if(this.transientHitTestSubscriptions_.has(subscriptionId)){
+      controller = this.transientHitTestSubscriptions_.get(subscriptionId).controller;
+      this.transientHitTestSubscriptions_.delete(subscriptionId);
+    } else if(this.hitTestSubscriptions_.has(subscriptionId)){
+      controller = this.hitTestSubscriptions_.get(subscriptionId).controller;
+      this.hitTestSubscriptions_.delete(subscriptionId);
+    }
+
+    if(controller) {
+      controller.deleted = true;
+    }
+  }
+
+  createAnchor(nativeOriginInformation, nativeOriginFromAnchor) {
+    return new Promise((resolve) => {
+      if(this.anchor_creation_callback_ == null) {
+        resolve({
+          result : vrMojom.CreateAnchorResult.FAILURE,
+          anchorId : 0n
+        });
+
+        return;
+      }
+
+      const mojoFromNativeOrigin = this._getMojoFromNativeOrigin(nativeOriginInformation);
+      if(mojoFromNativeOrigin == null) {
+        resolve({
+          result : vrMojom.CreateAnchorResult.FAILURE,
+          anchorId : 0n
+        });
+
+        return;
+      }
+
+      const mojoFromAnchor = XRMathHelper.mul4x4(mojoFromNativeOrigin, nativeOriginFromAnchor);
+
+      const anchorCreationParameters = {
+        requestedAnchorOrigin: mojoFromAnchor,
+        isAttachedToEntity: false,
+      };
+
+      const anchorController = new FakeXRAnchorController();
+
+      this.anchor_creation_callback_(anchorCreationParameters, anchorController)
+            .then((result) => {
+              if(result) {
+                // If the test allowed the anchor creation,
+                // store the anchor controller & return success.
+
+                const anchor_id = this.next_anchor_id_;
+                this.next_anchor_id_++;
+
+                this.anchor_controllers_.set(anchor_id, anchorController);
+                anchorController.device = this;
+                anchorController.id = anchor_id;
+
+                resolve({
+                  result : vrMojom.CreateAnchorResult.SUCCESS,
+                  anchorId : anchor_id
+                });
+              } else {
+                // The test has rejected anchor creation.
+                resolve({
+                  result : vrMojom.CreateAnchorResult.FAILURE,
+                  anchorId : 0n
+                });
+              }
+            })
+            .catch(() => {
+              // The test threw an error, treat anchor creation as failed.
+              resolve({
+                result : vrMojom.CreateAnchorResult.FAILURE,
+                anchorId : 0n
+              });
+            });
+    });
+  }
+
+  createPlaneAnchor(planeFromAnchor, planeId) {
+    return new Promise((resolve) => {
+
+      // Not supported yet.
+
+      resolve({
+        result : vrMojom.CreateAnchorResult.FAILURE,
+        anchorId : 0n,
+      });
+    });
+  }
+
+  detachAnchor(anchorId) {}
+
+  // Utility function
+  _requestRuntimeSession(sessionOptions) {
+    return this._runtimeSupportsSession(sessionOptions).then((result) => {
+      // The JavaScript bindings convert c_style_names to camelCase names.
+      const options = {
+        transportMethod:
+            vrMojom.XRPresentationTransportMethod.SUBMIT_AS_MAILBOX_HOLDER,
+        waitForTransferNotification: true,
+        waitForRenderNotification: true,
+        waitForGpuFence: false,
+      };
+
+      let submit_frame_sink;
+      if (result.supportsSession) {
+        submit_frame_sink = {
+          clientReceiver: this.presentation_provider_._getClientReceiver(),
+          provider: this.presentation_provider_._bindProvider(sessionOptions),
+          transportOptions: options
+        };
+
+        const dataProviderPtr = new vrMojom.XRFrameDataProviderRemote();
+        this.dataProviderReceiver_ =
+            new vrMojom.XRFrameDataProviderReceiver(this);
+        this.dataProviderReceiver_.$.bindHandle(
+            dataProviderPtr.$.bindNewPipeAndPassReceiver().handle);
+        this.sessionOptions_ = sessionOptions;
+
+        this.sessionClient_ = new vrMojom.XRSessionClientRemote();
+        const clientReceiver = this.sessionClient_.$.bindNewPipeAndPassReceiver();
+
+        const enabled_features = [];
+        for (let i = 0; i < sessionOptions.requiredFeatures.length; i++) {
+          if (this.supportedFeatures_.indexOf(sessionOptions.requiredFeatures[i]) !== -1) {
+            enabled_features.push(sessionOptions.requiredFeatures[i]);
+          } else {
+            return Promise.resolve({session: null});
+          }
+        }
+
+        for (let i =0; i < sessionOptions.optionalFeatures.length; i++) {
+          if (this.supportedFeatures_.indexOf(sessionOptions.optionalFeatures[i]) !== -1) {
+            enabled_features.push(sessionOptions.optionalFeatures[i]);
+          }
+        }
+
+        this.enabledFeatures_ = enabled_features;
+
+        return Promise.resolve({
+          session: {
+            submitFrameSink: submit_frame_sink,
+            dataProvider: dataProviderPtr,
+            clientReceiver: clientReceiver,
+            enabledFeatures: enabled_features,
+            deviceConfig: {
+              defaultFramebufferScale: this.defaultFramebufferScale_,
+              supportsViewportScaling: true,
+              depthConfiguration:
+                enabled_features.includes(xrSessionMojom.XRSessionFeature.DEPTH) ? {
+                  depthUsage: vrMojom.XRDepthUsage.kCPUOptimized,
+                  depthDataFormat: vrMojom.XRDepthDataFormat.kLuminanceAlpha,
+                } : null,
+              views: this._getDefaultViews(),
+            },
+            enviromentBlendMode: this.enviromentBlendMode_,
+            interactionMode: this.interactionMode_
+          }
+        });
+      } else {
+        return Promise.resolve({session: null});
+      }
+    });
+  }
+
+  _runtimeSupportsSession(options) {
+    let result = this.supportedModes_.includes(options.mode);
+
+    if (options.requiredFeatures.includes(xrSessionMojom.XRSessionFeature.DEPTH)
+    || options.optionalFeatures.includes(xrSessionMojom.XRSessionFeature.DEPTH)) {
+      result &= options.depthOptions.usagePreferences.includes(vrMojom.XRDepthUsage.kCPUOptimized);
+      result &= options.depthOptions.dataFormatPreferences.includes(vrMojom.XRDepthDataFormat.kLuminanceAlpha);
+    }
+
+    return Promise.resolve({
+      supportsSession: result,
+    });
+  }
+
+  // Private functions - utilities:
+  _nativeOriginKnown(nativeOriginInformation){
+
+    if (nativeOriginInformation.inputSourceSpaceInfo !== undefined) {
+      if (!this.input_sources_.has(nativeOriginInformation.inputSourceSpaceInfo.inputSourceId)) {
+        // Unknown input source.
+        return false;
+      }
+
+      return true;
+    } else if (nativeOriginInformation.referenceSpaceType !== undefined) {
+      // Bounded_floor & unbounded ref spaces are not yet supported for AR:
+      if (nativeOriginInformation.referenceSpaceType == vrMojom.XRReferenceSpaceType.kUnbounded
+       || nativeOriginInformation.referenceSpaceType == vrMojom.XRReferenceSpaceType.kBoundedFloor) {
+        return false;
+      }
+
+      return true;
+    } else {
+      // Planes and anchors are not yet supported by the mock interface.
+      return false;
+    }
+  }
+
+  // Private functions - anchors implementation:
+
+  // Modifies passed in frameData to add anchor information.
+  _calculateAnchorInformation(frameData) {
+    if (!this.supportedModes_.includes(xrSessionMojom.XRSessionMode.kImmersiveAr)) {
+      return;
+    }
+
+    frameData.anchorsData = {allAnchorsIds: [], updatedAnchorsData: []};
+    for(const [id, controller] of this.anchor_controllers_) {
+      frameData.anchorsData.allAnchorsIds.push(id);
+
+      // Send the entire anchor data over if there was a change since last GetFrameData().
+      if(controller.dirty) {
+        const anchorData = {id};
+        if(!controller.paused) {
+          anchorData.mojoFromAnchor = getPoseFromTransform(
+              XRMathHelper.decomposeRigidTransform(
+                  controller._getAnchorOrigin()));
+        }
+
+        controller._markProcessed();
+
+        frameData.anchorsData.updatedAnchorsData.push(anchorData);
+      }
+    }
+  }
+
+  // Private functions - depth sensing implementation:
+
+  // Modifies passed in frameData to add anchor information.
+  _calculateDepthInformation(frameData) {
+    if (!this.supportedModes_.includes(xrSessionMojom.XRSessionMode.kImmersiveAr)) {
+      return;
+    }
+
+    if (!this.enabledFeatures_.includes(xrSessionMojom.XRSessionFeature.DEPTH)) {
+      return;
+    }
+
+    // If we don't have a current depth data, we'll return null
+    // (i.e. no data is not a valid data, so it cannot be "StillValid").
+    if (this.depthSensingData_ == null) {
+      frameData.depthData = null;
+      return;
+    }
+
+    if(!this.depthSensingDataDirty_) {
+      frameData.depthData = { dataStillValid: {}};
+      return;
+    }
+
+    frameData.depthData = {
+      updatedDepthData: {
+        timeDelta: frameData.timeDelta,
+        normTextureFromNormView: this.depthSensingData_.normDepthBufferFromNormView,
+        rawValueToMeters: this.depthSensingData_.rawValueToMeters,
+        size: { width: this.depthSensingData_.width, height: this.depthSensingData_.height },
+        pixelData: { bytes: this.depthSensingData_.depthData }
+      }
+    };
+
+    this.depthSensingDataDirty_ = false;
+  }
+
+  // Private functions - hit test implementation:
+
+  // Returns a Promise<bool> that signifies whether hit test source creation should succeed.
+  // If we have a hit test source creation callback installed, invoke it and return its result.
+  // If it's not installed, for back-compat just return a promise that resolves to true.
+  _shouldHitTestSourceCreationSucceed(hitTestParameters, controller) {
+    if(this.hit_test_source_creation_callback_) {
+      return this.hit_test_source_creation_callback_(hitTestParameters, controller);
+    } else {
+      return Promise.resolve(true);
+    }
+  }
+
+  // Modifies passed in frameData to add hit test results.
+  _calculateHitTestResults(frameData) {
+    if (!this.supportedModes_.includes(xrSessionMojom.XRSessionMode.kImmersiveAr)) {
+      return;
+    }
+
+    frameData.hitTestSubscriptionResults = {results: [],
+                                            transientInputResults: []};
+    if (!this.world_) {
+      return;
+    }
+
+    // Non-transient hit test:
+    for (const [id, subscription] of this.hitTestSubscriptions_) {
+      const mojo_from_native_origin = this._getMojoFromNativeOrigin(subscription.nativeOriginInformation);
+      if (!mojo_from_native_origin) continue;
+
+      const [mojo_ray_origin, mojo_ray_direction] = this._transformRayToMojoSpace(
+        subscription.ray,
+        mojo_from_native_origin
+      );
+
+      const results = this._hitTestWorld(mojo_ray_origin, mojo_ray_direction, subscription.entityTypes);
+      frameData.hitTestSubscriptionResults.results.push(
+          {subscriptionId: id, hitTestResults: results});
+    }
+
+    // Transient hit test:
+    const mojo_from_viewer = this._getMojoFromViewer();
+
+    for (const [id, subscription] of this.transientHitTestSubscriptions_) {
+      const result = {subscriptionId: id,
+                      inputSourceIdToHitTestResults: new Map()};
+
+      // Find all input sources that match the profile name:
+      const matching_input_sources = Array.from(this.input_sources_.values())
+                                                        .filter(input_source => input_source.profiles_.includes(subscription.profileName));
+
+      for (const input_source of matching_input_sources) {
+        const mojo_from_native_origin = input_source._getMojoFromInputSource(mojo_from_viewer);
+
+        const [mojo_ray_origin, mojo_ray_direction] = this._transformRayToMojoSpace(
+          subscription.ray,
+          mojo_from_native_origin
+        );
+
+        const results = this._hitTestWorld(mojo_ray_origin, mojo_ray_direction, subscription.entityTypes);
+
+        result.inputSourceIdToHitTestResults.set(input_source.source_id_, results);
+      }
+
+      frameData.hitTestSubscriptionResults.transientInputResults.push(result);
+    }
+  }
+
+  // Returns 2-element array [origin, direction] of a ray in mojo space.
+  // |ray| is expressed relative to native origin.
+  _transformRayToMojoSpace(ray, mojo_from_native_origin) {
+    const ray_origin = {
+      x: ray.origin.x,
+      y: ray.origin.y,
+      z: ray.origin.z,
+      w: 1
+    };
+    const ray_direction = {
+      x: ray.direction.x,
+      y: ray.direction.y,
+      z: ray.direction.z,
+      w: 0
+    };
+
+    const mojo_ray_origin = XRMathHelper.transform_by_matrix(
+      mojo_from_native_origin,
+      ray_origin);
+    const mojo_ray_direction = XRMathHelper.transform_by_matrix(
+      mojo_from_native_origin,
+      ray_direction);
+
+    return [mojo_ray_origin, mojo_ray_direction];
+  }
+
+  // Hit tests the passed in ray (expressed as origin and direction) against the mocked world data.
+  _hitTestWorld(origin, direction, entityTypes) {
+    let result = [];
+
+    for (const region of this.world_.hitTestRegions) {
+      const partial_result = this._hitTestRegion(
+        region,
+        origin, direction,
+        entityTypes);
+
+      result = result.concat(partial_result);
+    }
+
+    return result.sort((lhs, rhs) => lhs.distance - rhs.distance).map((hitTest) => {
+      delete hitTest.distance;
+      return hitTest;
+    });
+  }
+
+  // Hit tests the passed in ray (expressed as origin and direction) against world region.
+  // |entityTypes| is a set of FakeXRRegionTypes.
+  // |region| is FakeXRRegion.
+  // Returns array of XRHitResults, each entry will be decorated with the distance from the ray origin (along the ray).
+  _hitTestRegion(region, origin, direction, entityTypes) {
+    const regionNameToMojoEnum = {
+      "point": vrMojom.EntityTypeForHitTest.POINT,
+      "plane": vrMojom.EntityTypeForHitTest.PLANE,
+      "mesh":null
+    };
+
+    if (!entityTypes.includes(regionNameToMojoEnum[region.type])) {
+      return [];
+    }
+
+    const result = [];
+    for (const face of region.faces) {
+      const maybe_hit = this._hitTestFace(face, origin, direction);
+      if (maybe_hit) {
+        result.push(maybe_hit);
+      }
+    }
+
+    // The results should be sorted by distance and there should be no 2 entries with
+    // the same distance from ray origin - that would mean they are the same point.
+    // This situation is possible when a ray intersects the region through an edge shared
+    // by 2 faces.
+    return result.sort((lhs, rhs) => lhs.distance - rhs.distance)
+                 .filter((val, index, array) => index === 0 || val.distance !== array[index - 1].distance);
+  }
+
+  // Hit tests the passed in ray (expressed as origin and direction) against a single face.
+  // |face|, |origin|, and |direction| are specified in world (aka mojo) coordinates.
+  // |face| is an array of DOMPointInits.
+  // Returns null if the face does not intersect with the ray, otherwise the result is
+  // an XRHitResult with matrix describing the pose of the intersection point.
+  _hitTestFace(face, origin, direction) {
+    const add = XRMathHelper.add;
+    const sub = XRMathHelper.sub;
+    const mul = XRMathHelper.mul;
+    const normalize = XRMathHelper.normalize;
+    const dot = XRMathHelper.dot;
+    const cross = XRMathHelper.cross;
+    const neg = XRMathHelper.neg;
+
+    //1. Calculate plane normal in world coordinates.
+    const point_A = face.vertices[0];
+    const point_B = face.vertices[1];
+    const point_C = face.vertices[2];
+
+    const edge_AB = sub(point_B, point_A);
+    const edge_AC = sub(point_C, point_A);
+
+    const normal = normalize(cross(edge_AB, edge_AC));
+
+    const numerator = dot(sub(point_A, origin), normal);
+    const denominator = dot(direction, normal);
+
+    if (Math.abs(denominator) < XRMathHelper.EPSILON) {
+      // Planes are nearly parallel - there's either infinitely many intersection points or 0.
+      // Both cases signify a "no hit" for us.
+      return null;
+    } else {
+      // Single intersection point between the infinite plane and the line (*not* ray).
+      // Need to calculate the hit test matrix taking into account the face vertices.
+      const distance = numerator / denominator;
+      if (distance < 0) {
+        // Line - plane intersection exists, but not the half-line - plane does not.
+        return null;
+      } else {
+        const intersection_point = add(origin, mul(distance, direction));
+        // Since we are treating the face as a solid, flip the normal so that its
+        // half-space will contain the ray origin.
+        const y_axis = denominator > 0 ? neg(normal) : normal;
+
+        let z_axis = null;
+        const cos_direction_and_y_axis = dot(direction, y_axis);
+        if (Math.abs(cos_direction_and_y_axis) > (1 - XRMathHelper.EPSILON)) {
+          // Ray and the hit test normal are co-linear - try using the 'up' or 'right' vector's projection on the face plane as the Z axis.
+          // Note: this edge case is currently not covered by the spec.
+          const up = {x: 0.0, y: 1.0, z: 0.0, w: 0.0};
+          const right = {x: 1.0, y: 0.0, z: 0.0, w: 0.0};
+
+          z_axis = Math.abs(dot(up, y_axis)) > (1 - XRMathHelper.EPSILON)
+                        ? sub(up, mul(dot(right, y_axis), y_axis))  // `up is also co-linear with hit test normal, use `right`
+                        : sub(up, mul(dot(up, y_axis), y_axis));    // `up` is not co-linear with hit test normal, use it
+        } else {
+          // Project the ray direction onto the plane, negate it and use as a Z axis.
+          z_axis = neg(sub(direction, mul(cos_direction_and_y_axis, y_axis))); // Z should point towards the ray origin, not away.
+        }
+
+        z_axis = normalize(z_axis);
+        const x_axis = normalize(cross(y_axis, z_axis));
+
+        // Filter out the points not in polygon.
+        if (!XRMathHelper.pointInFace(intersection_point, face)) {
+          return null;
+        }
+
+        const hitResult = {planeId: 0n};
+        hitResult.distance = distance;  // Extend the object with additional information used by higher layers.
+                                        // It will not be serialized over mojom.
+
+        const matrix = new Array(16);
+
+        matrix[0] = x_axis.x;
+        matrix[1] = x_axis.y;
+        matrix[2] = x_axis.z;
+        matrix[3] = 0;
+
+        matrix[4] = y_axis.x;
+        matrix[5] = y_axis.y;
+        matrix[6] = y_axis.z;
+        matrix[7] = 0;
+
+        matrix[8] = z_axis.x;
+        matrix[9] = z_axis.y;
+        matrix[10] = z_axis.z;
+        matrix[11] = 0;
+
+        matrix[12] = intersection_point.x;
+        matrix[13] = intersection_point.y;
+        matrix[14] = intersection_point.z;
+        matrix[15] = 1;
+
+        hitResult.mojoFromResult = getPoseFromTransform(
+            XRMathHelper.decomposeRigidTransform(matrix));
+        return hitResult;
+      }
+    }
+  }
+
+  _getMojoFromViewer() {
+    if (!this.pose_) {
+      return XRMathHelper.identity();
+    }
+    const transform = {
+      position: [
+        this.pose_.position.x,
+        this.pose_.position.y,
+        this.pose_.position.z],
+      orientation: [
+        this.pose_.orientation.x,
+        this.pose_.orientation.y,
+        this.pose_.orientation.z,
+        this.pose_.orientation.w],
+    };
+
+    return getMatrixFromTransform(transform);
+  }
+
+  _getMojoFromViewerWithOffset(viewOffset) {
+    return { matrix: XRMathHelper.mul4x4(this._getMojoFromViewer(), viewOffset.matrix) };
+  }
+
+  _getMojoFromNativeOrigin(nativeOriginInformation) {
+    const mojo_from_viewer = this._getMojoFromViewer();
+
+    if (nativeOriginInformation.inputSourceSpaceInfo !== undefined) {
+      if (!this.input_sources_.has(nativeOriginInformation.inputSourceSpaceInfo.inputSourceId)) {
+        return null;
+      } else {
+        const inputSource = this.input_sources_.get(nativeOriginInformation.inputSourceSpaceInfo.inputSourceId);
+        return inputSource._getMojoFromInputSource(mojo_from_viewer);
+      }
+    } else if (nativeOriginInformation.referenceSpaceType !== undefined) {
+      switch (nativeOriginInformation.referenceSpaceType) {
+        case vrMojom.XRReferenceSpaceType.kLocal:
+          return XRMathHelper.identity();
+        case vrMojom.XRReferenceSpaceType.kLocalFloor:
+          if (this.stageParameters_ == null || this.stageParameters_.mojoFromFloor == null) {
+            console.warn("Standing transform not available.");
+            return null;
+          }
+          return this.stageParameters_.mojoFromFloor.matrix;
+        case vrMojom.XRReferenceSpaceType.kViewer:
+          return mojo_from_viewer;
+        case vrMojom.XRReferenceSpaceType.kBoundedFloor:
+          return null;
+        case vrMojom.XRReferenceSpaceType.kUnbounded:
+          return null;
+        default:
+          throw new TypeError("Unrecognized XRReferenceSpaceType!");
+      }
+    } else {
+      // Anchors & planes are not yet supported for hit test.
+      return null;
+    }
+  }
+}
+
+class MockXRInputSource {
+  constructor(fakeInputSourceInit, id, pairedDevice) {
+    this.source_id_ = id;
+    this.pairedDevice_ = pairedDevice;
+    this.handedness_ = fakeInputSourceInit.handedness;
+    this.target_ray_mode_ = fakeInputSourceInit.targetRayMode;
+
+    if (fakeInputSourceInit.pointerOrigin == null) {
+      throw new TypeError("FakeXRInputSourceInit.pointerOrigin is required.");
+    }
+
+    this.setPointerOrigin(fakeInputSourceInit.pointerOrigin);
+    this.setProfiles(fakeInputSourceInit.profiles);
+
+    this.primary_input_pressed_ = false;
+    if (fakeInputSourceInit.selectionStarted != null) {
+      this.primary_input_pressed_ = fakeInputSourceInit.selectionStarted;
+    }
+
+    this.primary_input_clicked_ = false;
+    if (fakeInputSourceInit.selectionClicked != null) {
+      this.primary_input_clicked_ = fakeInputSourceInit.selectionClicked;
+    }
+
+    this.primary_squeeze_pressed_ = false;
+    this.primary_squeeze_clicked_ = false;
+
+    this.mojo_from_input_ = null;
+    if (fakeInputSourceInit.gripOrigin != null) {
+      this.setGripOrigin(fakeInputSourceInit.gripOrigin);
+    }
+
+    // This properly handles if supportedButtons were not specified.
+    this.setSupportedButtons(fakeInputSourceInit.supportedButtons);
+
+    this.emulated_position_ = false;
+    this.desc_dirty_ = true;
+  }
+
+  // WebXR Test API
+  setHandedness(handedness) {
+    if (this.handedness_ != handedness) {
+      this.desc_dirty_ = true;
+      this.handedness_ = handedness;
+    }
+  }
+
+  setTargetRayMode(targetRayMode) {
+    if (this.target_ray_mode_ != targetRayMode) {
+      this.desc_dirty_ = true;
+      this.target_ray_mode_ = targetRayMode;
+    }
+  }
+
+  setProfiles(profiles) {
+    this.desc_dirty_ = true;
+    this.profiles_ = profiles;
+  }
+
+  setGripOrigin(transform, emulatedPosition = false) {
+    // grip_origin was renamed to mojo_from_input in mojo
+    this.mojo_from_input_ = composeGFXTransform(transform);
+    this.emulated_position_ = emulatedPosition;
+
+    // Technically, setting the grip shouldn't make the description dirty, but
+    // the webxr-test-api sets our pointer as mojoFromPointer; however, we only
+    // support it across mojom as inputFromPointer, so we need to recalculate it
+    // whenever the grip moves.
+    this.desc_dirty_ = true;
+  }
+
+  clearGripOrigin() {
+    // grip_origin was renamed to mojo_from_input in mojo
+    if (this.mojo_from_input_ != null) {
+      this.mojo_from_input_ = null;
+      this.emulated_position_ = false;
+      this.desc_dirty_ = true;
+    }
+  }
+
+  setPointerOrigin(transform, emulatedPosition = false) {
+    // pointer_origin is mojo_from_pointer.
+    this.desc_dirty_ = true;
+    this.mojo_from_pointer_ = composeGFXTransform(transform);
+    this.emulated_position_ = emulatedPosition;
+  }
+
+  disconnect() {
+    this.pairedDevice_._removeInputSource(this);
+  }
+
+  reconnect() {
+    this.pairedDevice_._addInputSource(this);
+  }
+
+  startSelection() {
+    this.primary_input_pressed_ = true;
+    if (this.gamepad_) {
+      this.gamepad_.buttons[0].pressed = true;
+      this.gamepad_.buttons[0].touched = true;
+    }
+  }
+
+  endSelection() {
+    if (!this.primary_input_pressed_) {
+      throw new Error("Attempted to end selection which was not started");
+    }
+
+    this.primary_input_pressed_ = false;
+    this.primary_input_clicked_ = true;
+
+    if (this.gamepad_) {
+      this.gamepad_.buttons[0].pressed = false;
+      this.gamepad_.buttons[0].touched = false;
+    }
+  }
+
+  simulateSelect() {
+    this.primary_input_clicked_ = true;
+  }
+
+  setSupportedButtons(supportedButtons) {
+    this.gamepad_ = null;
+    this.supported_buttons_ = [];
+
+    // If there are no supported buttons, we can stop now.
+    if (supportedButtons == null || supportedButtons.length < 1) {
+      return;
+    }
+
+    const supported_button_map = {};
+    this.gamepad_ = this._getEmptyGamepad();
+    for (let i = 0; i < supportedButtons.length; i++) {
+      const buttonType = supportedButtons[i].buttonType;
+      this.supported_buttons_.push(buttonType);
+      supported_button_map[buttonType] = supportedButtons[i];
+    }
+
+    // Let's start by building the button state in order of priority:
+    // Primary button is index 0.
+    this.gamepad_.buttons.push({
+      pressed: this.primary_input_pressed_,
+      touched: this.primary_input_pressed_,
+      value: this.primary_input_pressed_ ? 1.0 : 0.0
+    });
+
+    // Now add the rest of our buttons
+    this._addGamepadButton(supported_button_map['grip']);
+    this._addGamepadButton(supported_button_map['touchpad']);
+    this._addGamepadButton(supported_button_map['thumbstick']);
+    this._addGamepadButton(supported_button_map['optional-button']);
+    this._addGamepadButton(supported_button_map['optional-thumbstick']);
+
+    // Finally, back-fill placeholder buttons/axes
+    for (let i = 0; i < this.gamepad_.buttons.length; i++) {
+      if (this.gamepad_.buttons[i] == null) {
+        this.gamepad_.buttons[i] = {
+          pressed: false,
+          touched: false,
+          value: 0
+        };
+      }
+    }
+
+    for (let i=0; i < this.gamepad_.axes.length; i++) {
+      if (this.gamepad_.axes[i] == null) {
+        this.gamepad_.axes[i] = 0;
+      }
+    }
+  }
+
+  updateButtonState(buttonState) {
+    if (this.supported_buttons_.indexOf(buttonState.buttonType) == -1) {
+      throw new Error("Tried to update state on an unsupported button");
+    }
+
+    const buttonIndex = this._getButtonIndex(buttonState.buttonType);
+    const axesStartIndex = this._getAxesStartIndex(buttonState.buttonType);
+
+    if (buttonIndex == -1) {
+      throw new Error("Unknown Button Type!");
+    }
+
+    // is this a 'squeeze' button?
+    if (buttonIndex === this._getButtonIndex('grip')) {
+      // squeeze
+      if (buttonState.pressed) {
+        this.primary_squeeze_pressed_ = true;
+      } else if (this.gamepad_.buttons[buttonIndex].pressed) {
+        this.primary_squeeze_clicked_ = true;
+        this.primary_squeeze_pressed_ = false;
+      } else {
+        this.primary_squeeze_clicked_ = false;
+        this.primary_squeeze_pressed_ = false;
+      }
+    }
+
+    this.gamepad_.buttons[buttonIndex].pressed = buttonState.pressed;
+    this.gamepad_.buttons[buttonIndex].touched = buttonState.touched;
+    this.gamepad_.buttons[buttonIndex].value = buttonState.pressedValue;
+
+    if (axesStartIndex != -1) {
+      this.gamepad_.axes[axesStartIndex] = buttonState.xValue == null ? 0.0 : buttonState.xValue;
+      this.gamepad_.axes[axesStartIndex + 1] = buttonState.yValue == null ? 0.0 : buttonState.yValue;
+    }
+  }
+
+  // DOM Overlay Extensions
+  setOverlayPointerPosition(x, y) {
+    this.overlay_pointer_position_ = {x: x, y: y};
+  }
+
+  // Helpers for Mojom
+  _getInputSourceState() {
+    const input_state = {};
+
+    input_state.sourceId = this.source_id_;
+    input_state.isAuxiliary = false;
+
+    input_state.primaryInputPressed = this.primary_input_pressed_;
+    input_state.primaryInputClicked = this.primary_input_clicked_;
+
+    input_state.primarySqueezePressed = this.primary_squeeze_pressed_;
+    input_state.primarySqueezeClicked = this.primary_squeeze_clicked_;
+    // Setting the input source's "clicked" state should generate one "select"
+    // event. Reset the input value to prevent it from continuously generating
+    // events.
+    this.primary_input_clicked_ = false;
+    // Setting the input source's "clicked" state should generate one "squeeze"
+    // event. Reset the input value to prevent it from continuously generating
+    // events.
+    this.primary_squeeze_clicked_ = false;
+
+    input_state.mojoFromInput = this.mojo_from_input_;
+
+    input_state.gamepad = this.gamepad_;
+
+    input_state.emulatedPosition = this.emulated_position_;
+
+    if (this.desc_dirty_) {
+      const input_desc = {};
+
+      switch (this.target_ray_mode_) {
+        case 'gaze':
+          input_desc.targetRayMode = vrMojom.XRTargetRayMode.GAZING;
+          break;
+        case 'tracked-pointer':
+          input_desc.targetRayMode = vrMojom.XRTargetRayMode.POINTING;
+          break;
+        case 'screen':
+          input_desc.targetRayMode = vrMojom.XRTargetRayMode.TAPPING;
+          break;
+        default:
+          throw new Error('Unhandled target ray mode ' + this.target_ray_mode_);
+      }
+
+      switch (this.handedness_) {
+        case 'left':
+          input_desc.handedness = vrMojom.XRHandedness.LEFT;
+          break;
+        case 'right':
+          input_desc.handedness = vrMojom.XRHandedness.RIGHT;
+          break;
+        default:
+          input_desc.handedness = vrMojom.XRHandedness.NONE;
+          break;
+      }
+
+      // Mojo requires us to send the pointerOrigin as relative to the grip
+      // space. If we don't have a grip space, we'll just assume that there
+      // is a grip at identity. This allows tests to simulate controllers that
+      // are really just a pointer with no tracked grip, though we will end up
+      // exposing that grip space.
+      let mojo_from_input = XRMathHelper.identity();
+      switch (this.target_ray_mode_) {
+        case 'gaze':
+        case 'screen':
+          // For gaze and screen space, we won't have a mojo_from_input; however
+          // the "input" position is just the viewer, so use mojo_from_viewer.
+          mojo_from_input = this.pairedDevice_._getMojoFromViewer();
+          break;
+        case 'tracked-pointer':
+          // If we have a tracked grip position (e.g. mojo_from_input), then use
+          // that. If we don't, then we'll just set the pointer offset directly,
+          // using identity as set above.
+          if (this.mojo_from_input_) {
+            mojo_from_input = this.mojo_from_input_.matrix;
+          }
+          break;
+        default:
+          throw new Error('Unhandled target ray mode ' + this.target_ray_mode_);
+      }
+
+      // To convert mojo_from_pointer to input_from_pointer, we need:
+      // input_from_pointer = input_from_mojo * mojo_from_pointer
+      // Since we store mojo_from_input, we need to invert it here before
+      // multiplying.
+      let input_from_mojo = XRMathHelper.inverse(mojo_from_input);
+      input_desc.inputFromPointer = {};
+      input_desc.inputFromPointer.matrix =
+        XRMathHelper.mul4x4(input_from_mojo, this.mojo_from_pointer_.matrix);
+
+      input_desc.profiles = this.profiles_;
+
+      input_state.description = input_desc;
+
+      this.desc_dirty_ = false;
+    }
+
+    // Pointer data for DOM Overlay, set by setOverlayPointerPosition()
+    if (this.overlay_pointer_position_) {
+      input_state.overlayPointerPosition = this.overlay_pointer_position_;
+      this.overlay_pointer_position_ = null;
+    }
+
+    return input_state;
+  }
+
+  _getEmptyGamepad() {
+    // Mojo complains if some of the properties on Gamepad are null, so set
+    // everything to reasonable defaults that tests can override.
+    const gamepad = {
+      connected: true,
+      id: [],
+      timestamp: 0n,
+      axes: [],
+      buttons: [],
+      touchEvents: [],
+      mapping: GamepadMapping.GamepadMappingStandard,
+      displayId: 0,
+    };
+
+    switch (this.handedness_) {
+      case 'left':
+      gamepad.hand = GamepadHand.GamepadHandLeft;
+      break;
+      case 'right':
+      gamepad.hand = GamepadHand.GamepadHandRight;
+      break;
+      default:
+      gamepad.hand = GamepadHand.GamepadHandNone;
+      break;
+    }
+
+    return gamepad;
+  }
+
+  _addGamepadButton(buttonState) {
+    if (buttonState == null) {
+      return;
+    }
+
+    const buttonIndex = this._getButtonIndex(buttonState.buttonType);
+    const axesStartIndex = this._getAxesStartIndex(buttonState.buttonType);
+
+    if (buttonIndex == -1) {
+      throw new Error("Unknown Button Type!");
+    }
+
+    this.gamepad_.buttons[buttonIndex] = {
+      pressed: buttonState.pressed,
+      touched: buttonState.touched,
+      value: buttonState.pressedValue
+    };
+
+    // Add x/y value if supported.
+    if (axesStartIndex != -1) {
+      this.gamepad_.axes[axesStartIndex] = (buttonState.xValue == null ? 0.0 : buttonSate.xValue);
+      this.gamepad_.axes[axesStartIndex + 1] = (buttonState.yValue == null ? 0.0 : buttonSate.yValue);
+    }
+  }
+
+  // General Helper methods
+  _getButtonIndex(buttonType) {
+    switch (buttonType) {
+      case 'grip':
+        return 1;
+      case 'touchpad':
+        return 2;
+      case 'thumbstick':
+        return 3;
+      case 'optional-button':
+        return 4;
+      case 'optional-thumbstick':
+        return 5;
+      default:
+        return -1;
+    }
+  }
+
+  _getAxesStartIndex(buttonType) {
+    switch (buttonType) {
+      case 'touchpad':
+        return 0;
+      case 'thumbstick':
+        return 2;
+      case 'optional-thumbstick':
+        return 4;
+      default:
+        return -1;
+    }
+  }
+
+  _getMojoFromInputSource(mojo_from_viewer) {
+    return this.mojo_from_pointer_.matrix;
+  }
+}
+
+// Mojo helper classes
+class FakeXRHitTestSourceController {
+  constructor(id) {
+    this.id_ = id;
+    this.deleted_ = false;
+  }
+
+  get deleted() {
+    return this.deleted_;
+  }
+
+  // Internal setter:
+  set deleted(value) {
+    this.deleted_ = value;
+  }
+}
+
+class MockXRPresentationProvider {
+  constructor() {
+    this.receiver_ = null;
+    this.submit_frame_count_ = 0;
+    this.missing_frame_count_ = 0;
+  }
+
+  _bindProvider() {
+    const provider = new vrMojom.XRPresentationProviderRemote();
+
+    if (this.receiver_) {
+      this.receiver_.$.close();
+    }
+    this.receiver_ = new vrMojom.XRPresentationProviderReceiver(this);
+    this.receiver_.$.bindHandle(provider.$.bindNewPipeAndPassReceiver().handle);
+    return provider;
+  }
+
+  _getClientReceiver() {
+    this.submitFrameClient_ = new vrMojom.XRPresentationClientRemote();
+    return this.submitFrameClient_.$.bindNewPipeAndPassReceiver();
+  }
+
+  // XRPresentationProvider mojo implementation
+  updateLayerBounds(frameId, leftBounds, rightBounds, sourceSize) {}
+
+  submitFrameMissing(frameId, mailboxHolder, timeWaited) {
+    this.missing_frame_count_++;
+  }
+
+  submitFrame(frameId, mailboxHolder, timeWaited) {
+    this.submit_frame_count_++;
+
+    // Trigger the submit completion callbacks here. WARNING: The
+    // Javascript-based mojo mocks are *not* re-entrant. It's OK to
+    // wait for these notifications on the next frame, but waiting
+    // within the current frame would never finish since the incoming
+    // calls would be queued until the current execution context finishes.
+    this.submitFrameClient_.onSubmitFrameTransferred(true);
+    this.submitFrameClient_.onSubmitFrameRendered();
+  }
+
+  submitFrameWithTextureHandle(frameId, texture, syncToken) {}
+
+  submitFrameDrawnIntoTexture(frameId, syncToken, timeWaited) {}
+
+  // Utility methods
+  _close() {
+    if (this.receiver_) {
+      this.receiver_.$.close();
+    }
+  }
+}
+
+// Export these into the global object as a side effect of importing this
+// module.
+self.ChromeXRTest = ChromeXRTest;
+self.MockRuntime = MockRuntime;
+self.MockVRService = MockVRService;
+self.SubscribeToHitTestResult = vrMojom.SubscribeToHitTestResult;
+
+navigator.xr.test = new ChromeXRTest();
diff --git a/test/wpt/tests/resources/chromium/webxr-test.js.headers b/test/wpt/tests/resources/chromium/webxr-test.js.headers
new file mode 100644
index 0000000..6805c32
--- /dev/null
+++ b/test/wpt/tests/resources/chromium/webxr-test.js.headers
@@ -0,0 +1 @@
+Content-Type: text/javascript; charset=utf-8
diff --git a/test/wpt/tests/resources/declarative-shadow-dom-polyfill.js b/test/wpt/tests/resources/declarative-shadow-dom-polyfill.js
new file mode 100644
index 0000000..99a3e91
--- /dev/null
+++ b/test/wpt/tests/resources/declarative-shadow-dom-polyfill.js
@@ -0,0 +1,25 @@
+/*
+ * Polyfill for attaching shadow trees for declarative Shadow DOM for
+ * implementations that do not support declarative Shadow DOM.
+ *
+ * Note: this polyfill will feature-detect the native feature, and do nothing
+ *       if supported.
+ *
+ * See: https://github.com/whatwg/html/pull/5465
+ *
+ * root: The root of the subtree in which to upgrade shadow roots
+ *
+ */
+
+function polyfill_declarative_shadow_dom(root) {
+  if (HTMLTemplateElement.prototype.hasOwnProperty('shadowRootMode'))
+    return;
+  root.querySelectorAll("template[shadowrootmode]").forEach(template => {
+    const mode = template.getAttribute("shadowrootmode");
+    const delegatesFocus = template.hasAttribute("shadowrootdelegatesfocus");
+    const shadowRoot = template.parentNode.attachShadow({ mode, delegatesFocus });
+    shadowRoot.appendChild(template.content);
+    template.remove();
+    polyfill_declarative_shadow_dom(shadowRoot);
+  });
+}
diff --git a/test/wpt/tests/resources/idlharness-shadowrealm.js b/test/wpt/tests/resources/idlharness-shadowrealm.js
new file mode 100644
index 0000000..9484ca6
--- /dev/null
+++ b/test/wpt/tests/resources/idlharness-shadowrealm.js
@@ -0,0 +1,61 @@
+// TODO: it would be nice to support `idl_array.add_objects`
+function fetch_text(url) {
+    return fetch(url).then(function (r) {
+        if (!r.ok) {
+            throw new Error("Error fetching " + url + ".");
+        }
+        return r.text();
+    });
+}
+
+/**
+ * idl_test_shadowrealm is a promise_test wrapper that handles the fetching of the IDL, and
+ * running the code in a `ShadowRealm`, avoiding repetitive boilerplate.
+ *
+ * @see https://github.com/tc39/proposal-shadowrealm
+ * @param {String[]} srcs Spec name(s) for source idl files (fetched from
+ *      /interfaces/{name}.idl).
+ * @param {String[]} deps Spec name(s) for dependency idl files (fetched
+ *      from /interfaces/{name}.idl). Order is important - dependencies from
+ *      each source will only be included if they're already know to be a
+ *      dependency (i.e. have already been seen).
+ */
+function idl_test_shadowrealm(srcs, deps) {
+    promise_setup(async t => {
+        const realm = new ShadowRealm();
+        // https://github.com/web-platform-tests/wpt/issues/31996
+        realm.evaluate("globalThis.self = globalThis; undefined;");
+
+        realm.evaluate(`
+            globalThis.self.GLOBAL = {
+                isWindow: function() { return false; },
+                isWorker: function() { return false; },
+                isShadowRealm: function() { return true; },
+            }; undefined;
+        `);
+        const specs = await Promise.all(srcs.concat(deps).map(spec => {
+            return fetch_text("/interfaces/" + spec + ".idl");
+        }));
+        const idls = JSON.stringify(specs);
+        await new Promise(
+            realm.evaluate(`(resolve,reject) => {
+                (async () => {
+                    await import("/resources/testharness.js");
+                    await import("/resources/WebIDLParser.js");
+                    await import("/resources/idlharness.js");
+                    const idls = ${idls};
+                    const idl_array = new IdlArray();
+                    for (let i = 0; i < ${srcs.length}; i++) {
+                        idl_array.add_idls(idls[i]);
+                    }
+                    for (let i = ${srcs.length}; i < ${srcs.length + deps.length}; i++) {
+                        idl_array.add_dependency_idls(idls[i]);
+                    }
+                    idl_array.test();
+                })().then(resolve, (e) => reject(e.toString()));
+            }`)
+        );
+        await fetch_tests_from_shadow_realm(realm);
+    });
+}
+// vim: set expandtab shiftwidth=4 tabstop=4 foldmarker=@{,@} foldmethod=marker:
diff --git a/test/wpt/tests/resources/idlharness.js b/test/wpt/tests/resources/idlharness.js
new file mode 100644
index 0000000..8f741b0
--- /dev/null
+++ b/test/wpt/tests/resources/idlharness.js
@@ -0,0 +1,3554 @@
+/* For user documentation see docs/_writing-tests/idlharness.md */
+
+/**
+ * Notes for people who want to edit this file (not just use it as a library):
+ *
+ * Most of the interesting stuff happens in the derived classes of IdlObject,
+ * especially IdlInterface.  The entry point for all IdlObjects is .test(),
+ * which is called by IdlArray.test().  An IdlObject is conceptually just
+ * "thing we want to run tests on", and an IdlArray is an array of IdlObjects
+ * with some additional data thrown in.
+ *
+ * The object model is based on what WebIDLParser.js produces, which is in turn
+ * based on its pegjs grammar.  If you want to figure out what properties an
+ * object will have from WebIDLParser.js, the best way is to look at the
+ * grammar:
+ *
+ *   https://github.com/darobin/webidl.js/blob/master/lib/grammar.peg
+ *
+ * So for instance:
+ *
+ *   // interface definition
+ *   interface
+ *       =   extAttrs:extendedAttributeList? S? "interface" S name:identifier w herit:ifInheritance? w "{" w mem:ifMember* w "}" w ";" w
+ *           { return { type: "interface", name: name, inheritance: herit, members: mem, extAttrs: extAttrs }; }
+ *
+ * This means that an "interface" object will have a .type property equal to
+ * the string "interface", a .name property equal to the identifier that the
+ * parser found, an .inheritance property equal to either null or the result of
+ * the "ifInheritance" production found elsewhere in the grammar, and so on.
+ * After each grammatical production is a JavaScript function in curly braces
+ * that gets called with suitable arguments and returns some JavaScript value.
+ *
+ * (Note that the version of WebIDLParser.js we use might sometimes be
+ * out-of-date or forked.)
+ *
+ * The members and methods of the classes defined by this file are all at least
+ * briefly documented, hopefully.
+ */
+(function(){
+"use strict";
+// Support subsetTestByKey from /common/subset-tests-by-key.js, but make it optional
+if (!('subsetTestByKey' in self)) {
+    self.subsetTestByKey = function(key, callback, ...args) {
+      return callback(...args);
+    }
+    self.shouldRunSubTest = () => true;
+}
+/// Helpers ///
+function constValue (cnt)
+{
+    if (cnt.type === "null") return null;
+    if (cnt.type === "NaN") return NaN;
+    if (cnt.type === "Infinity") return cnt.negative ? -Infinity : Infinity;
+    if (cnt.type === "number") return +cnt.value;
+    return cnt.value;
+}
+
+function minOverloadLength(overloads)
+{
+    // "The value of the Function object’s “length” property is
+    // a Number determined as follows:
+    // ". . .
+    // "Return the length of the shortest argument list of the
+    // entries in S."
+    if (!overloads.length) {
+        return 0;
+    }
+
+    return overloads.map(function(attr) {
+        return attr.arguments ? attr.arguments.filter(function(arg) {
+            return !arg.optional && !arg.variadic;
+        }).length : 0;
+    })
+    .reduce(function(m, n) { return Math.min(m, n); });
+}
+
+// A helper to get the global of a Function object.  This is needed to determine
+// which global exceptions the function throws will come from.
+function globalOf(func)
+{
+    try {
+        // Use the fact that .constructor for a Function object is normally the
+        // Function constructor, which can be used to mint a new function in the
+        // right global.
+        return func.constructor("return this;")();
+    } catch (e) {
+    }
+    // If the above fails, because someone gave us a non-function, or a function
+    // with a weird proto chain or weird .constructor property, just fall back
+    // to 'self'.
+    return self;
+}
+
+// https://esdiscuss.org/topic/isconstructor#content-11
+function isConstructor(o) {
+    try {
+        new (new Proxy(o, {construct: () => ({})}));
+        return true;
+    } catch(e) {
+        return false;
+    }
+}
+
+function throwOrReject(a_test, operation, fn, obj, args, message, cb)
+{
+    if (operation.idlType.generic !== "Promise") {
+        assert_throws_js(globalOf(fn).TypeError, function() {
+            fn.apply(obj, args);
+        }, message);
+        cb();
+    } else {
+        try {
+            promise_rejects_js(a_test, TypeError, fn.apply(obj, args), message).then(cb, cb);
+        } catch (e){
+            a_test.step(function() {
+                assert_unreached("Throws \"" + e + "\" instead of rejecting promise");
+                cb();
+            });
+        }
+    }
+}
+
+function awaitNCallbacks(n, cb, ctx)
+{
+    var counter = 0;
+    return function() {
+        counter++;
+        if (counter >= n) {
+            cb();
+        }
+    };
+}
+
+/// IdlHarnessError ///
+// Entry point
+self.IdlHarnessError = function(message)
+{
+    /**
+     * Message to be printed as the error's toString invocation.
+     */
+    this.message = message;
+};
+
+IdlHarnessError.prototype = Object.create(Error.prototype);
+
+IdlHarnessError.prototype.toString = function()
+{
+    return this.message;
+};
+
+
+/// IdlArray ///
+// Entry point
+self.IdlArray = function()
+{
+    /**
+     * A map from strings to the corresponding named IdlObject, such as
+     * IdlInterface or IdlException.  These are the things that test() will run
+     * tests on.
+     */
+    this.members = {};
+
+    /**
+     * A map from strings to arrays of strings.  The keys are interface or
+     * exception names, and are expected to also exist as keys in this.members
+     * (otherwise they'll be ignored).  This is populated by add_objects() --
+     * see documentation at the start of the file.  The actual tests will be
+     * run by calling this.members[name].test_object(obj) for each obj in
+     * this.objects[name].  obj is a string that will be eval'd to produce a
+     * JavaScript value, which is supposed to be an object implementing the
+     * given IdlObject (interface, exception, etc.).
+     */
+    this.objects = {};
+
+    /**
+     * When adding multiple collections of IDLs one at a time, an earlier one
+     * might contain a partial interface or includes statement that depends
+     * on a later one.  Save these up and handle them right before we run
+     * tests.
+     *
+     * Both this.partials and this.includes will be the objects as parsed by
+     * WebIDLParser.js, not wrapped in IdlInterface or similar.
+     */
+    this.partials = [];
+    this.includes = [];
+
+    /**
+     * Record of skipped IDL items, in case we later realize that they are a
+     * dependency (to retroactively process them).
+     */
+    this.skipped = new Map();
+};
+
+IdlArray.prototype.add_idls = function(raw_idls, options)
+{
+    /** Entry point.  See documentation at beginning of file. */
+    this.internal_add_idls(WebIDL2.parse(raw_idls), options);
+};
+
+IdlArray.prototype.add_untested_idls = function(raw_idls, options)
+{
+    /** Entry point.  See documentation at beginning of file. */
+    var parsed_idls = WebIDL2.parse(raw_idls);
+    this.mark_as_untested(parsed_idls);
+    this.internal_add_idls(parsed_idls, options);
+};
+
+IdlArray.prototype.mark_as_untested = function (parsed_idls)
+{
+    for (var i = 0; i < parsed_idls.length; i++) {
+        parsed_idls[i].untested = true;
+        if ("members" in parsed_idls[i]) {
+            for (var j = 0; j < parsed_idls[i].members.length; j++) {
+                parsed_idls[i].members[j].untested = true;
+            }
+        }
+    }
+};
+
+IdlArray.prototype.is_excluded_by_options = function (name, options)
+{
+    return options &&
+        (options.except && options.except.includes(name)
+         || options.only && !options.only.includes(name));
+};
+
+IdlArray.prototype.add_dependency_idls = function(raw_idls, options)
+{
+    return this.internal_add_dependency_idls(WebIDL2.parse(raw_idls), options);
+};
+
+IdlArray.prototype.internal_add_dependency_idls = function(parsed_idls, options)
+{
+    const new_options = { only: [] }
+
+    const all_deps = new Set();
+    Object.values(this.members).forEach(v => {
+        if (v.base) {
+            all_deps.add(v.base);
+        }
+    });
+    // Add both 'A' and 'B' for each 'A includes B' entry.
+    this.includes.forEach(i => {
+        all_deps.add(i.target);
+        all_deps.add(i.includes);
+    });
+    this.partials.forEach(p => all_deps.add(p.name));
+    // Add 'TypeOfType' for each "typedef TypeOfType MyType;" entry.
+    Object.entries(this.members).forEach(([k, v]) => {
+        if (v instanceof IdlTypedef) {
+            let defs = v.idlType.union
+                ? v.idlType.idlType.map(t => t.idlType)
+                : [v.idlType.idlType];
+            defs.forEach(d => all_deps.add(d));
+        }
+    });
+
+    // Add the attribute idlTypes of all the nested members of idls.
+    const attrDeps = parsedIdls => {
+        return parsedIdls.reduce((deps, parsed) => {
+            if (parsed.members) {
+                for (const attr of Object.values(parsed.members).filter(m => m.type === 'attribute')) {
+                    let attrType = attr.idlType;
+                    // Check for generic members (e.g. FrozenArray<MyType>)
+                    if (attrType.generic) {
+                        deps.add(attrType.generic);
+                        attrType = attrType.idlType;
+                    }
+                    deps.add(attrType.idlType);
+                }
+            }
+            if (parsed.base in this.members) {
+                attrDeps([this.members[parsed.base]]).forEach(dep => deps.add(dep));
+            }
+            return deps;
+        }, new Set());
+    };
+
+    const testedMembers = Object.values(this.members).filter(m => !m.untested && m.members);
+    attrDeps(testedMembers).forEach(dep => all_deps.add(dep));
+
+    const testedPartials = this.partials.filter(m => !m.untested && m.members);
+    attrDeps(testedPartials).forEach(dep => all_deps.add(dep));
+
+
+    if (options && options.except && options.only) {
+        throw new IdlHarnessError("The only and except options can't be used together.");
+    }
+
+    const defined_or_untested = name => {
+        // NOTE: Deps are untested, so we're lenient, and skip re-encountered definitions.
+        // e.g. for 'idl' containing A:B, B:C, C:D
+        //      array.add_idls(idl, {only: ['A','B']}).
+        //      array.add_dependency_idls(idl);
+        // B would be encountered as tested, and encountered as a dep, so we ignore.
+        return name in this.members
+            || this.is_excluded_by_options(name, options);
+    }
+    // Maps name -> [parsed_idl, ...]
+    const process = function(parsed) {
+        var deps = [];
+        if (parsed.name) {
+            deps.push(parsed.name);
+        } else if (parsed.type === "includes") {
+            deps.push(parsed.target);
+            deps.push(parsed.includes);
+        }
+
+        deps = deps.filter(function(name) {
+            if (!name
+                || name === parsed.name && defined_or_untested(name)
+                || !all_deps.has(name)) {
+                // Flag as skipped, if it's not already processed, so we can
+                // come back to it later if we retrospectively call it a dep.
+                if (name && !(name in this.members)) {
+                    this.skipped.has(name)
+                        ? this.skipped.get(name).push(parsed)
+                        : this.skipped.set(name, [parsed]);
+                }
+                return false;
+            }
+            return true;
+        }.bind(this));
+
+        deps.forEach(function(name) {
+            if (!new_options.only.includes(name)) {
+                new_options.only.push(name);
+            }
+
+            const follow_up = new Set();
+            for (const dep_type of ["inheritance", "includes"]) {
+                if (parsed[dep_type]) {
+                    const inheriting = parsed[dep_type];
+                    const inheritor = parsed.name || parsed.target;
+                    const deps = [inheriting];
+                    // For A includes B, we can ignore A, unless B (or some of its
+                    // members) is being tested.
+                    if (dep_type !== "includes"
+                        || inheriting in this.members && !this.members[inheriting].untested
+                        || this.partials.some(function(p) {
+                                return p.name === inheriting;
+                            })) {
+                        deps.push(inheritor);
+                    }
+                    for (const dep of deps) {
+                        if (!new_options.only.includes(dep)) {
+                            new_options.only.push(dep);
+                        }
+                        all_deps.add(dep);
+                        follow_up.add(dep);
+                    }
+                }
+            }
+
+            for (const deferred of follow_up) {
+                if (this.skipped.has(deferred)) {
+                    const next = this.skipped.get(deferred);
+                    this.skipped.delete(deferred);
+                    next.forEach(process);
+                }
+            }
+        }.bind(this));
+    }.bind(this);
+
+    for (let parsed of parsed_idls) {
+        process(parsed);
+    }
+
+    this.mark_as_untested(parsed_idls);
+
+    if (new_options.only.length) {
+        this.internal_add_idls(parsed_idls, new_options);
+    }
+}
+
+IdlArray.prototype.internal_add_idls = function(parsed_idls, options)
+{
+    /**
+     * Internal helper called by add_idls() and add_untested_idls().
+     *
+     * parsed_idls is an array of objects that come from WebIDLParser.js's
+     * "definitions" production.  The add_untested_idls() entry point
+     * additionally sets an .untested property on each object (and its
+     * .members) so that they'll be skipped by test() -- they'll only be
+     * used for base interfaces of tested interfaces, return types, etc.
+     *
+     * options is a dictionary that can have an only or except member which are
+     * arrays. If only is given then only members, partials and interface
+     * targets listed will be added, and if except is given only those that
+     * aren't listed will be added. Only one of only and except can be used.
+     */
+
+    if (options && options.only && options.except)
+    {
+        throw new IdlHarnessError("The only and except options can't be used together.");
+    }
+
+    var should_skip = name => {
+        return this.is_excluded_by_options(name, options);
+    }
+
+    parsed_idls.forEach(function(parsed_idl)
+    {
+        var partial_types = [
+            "interface",
+            "interface mixin",
+            "dictionary",
+            "namespace",
+        ];
+        if (parsed_idl.partial && partial_types.includes(parsed_idl.type))
+        {
+            if (should_skip(parsed_idl.name))
+            {
+                return;
+            }
+            this.partials.push(parsed_idl);
+            return;
+        }
+
+        if (parsed_idl.type == "includes")
+        {
+            if (should_skip(parsed_idl.target))
+            {
+                return;
+            }
+            this.includes.push(parsed_idl);
+            return;
+        }
+
+        parsed_idl.array = this;
+        if (should_skip(parsed_idl.name))
+        {
+            return;
+        }
+        if (parsed_idl.name in this.members)
+        {
+            throw new IdlHarnessError("Duplicate identifier " + parsed_idl.name);
+        }
+
+        switch(parsed_idl.type)
+        {
+        case "interface":
+            this.members[parsed_idl.name] =
+                new IdlInterface(parsed_idl, /* is_callback = */ false, /* is_mixin = */ false);
+            break;
+
+        case "interface mixin":
+            this.members[parsed_idl.name] =
+                new IdlInterface(parsed_idl, /* is_callback = */ false, /* is_mixin = */ true);
+            break;
+
+        case "dictionary":
+            // Nothing to test, but we need the dictionary info around for type
+            // checks
+            this.members[parsed_idl.name] = new IdlDictionary(parsed_idl);
+            break;
+
+        case "typedef":
+            this.members[parsed_idl.name] = new IdlTypedef(parsed_idl);
+            break;
+
+        case "callback":
+            this.members[parsed_idl.name] = new IdlCallback(parsed_idl);
+            break;
+
+        case "enum":
+            this.members[parsed_idl.name] = new IdlEnum(parsed_idl);
+            break;
+
+        case "callback interface":
+            this.members[parsed_idl.name] =
+                new IdlInterface(parsed_idl, /* is_callback = */ true, /* is_mixin = */ false);
+            break;
+
+        case "namespace":
+            this.members[parsed_idl.name] = new IdlNamespace(parsed_idl);
+            break;
+
+        default:
+            throw parsed_idl.name + ": " + parsed_idl.type + " not yet supported";
+        }
+    }.bind(this));
+};
+
+IdlArray.prototype.add_objects = function(dict)
+{
+    /** Entry point.  See documentation at beginning of file. */
+    for (var k in dict)
+    {
+        if (k in this.objects)
+        {
+            this.objects[k] = this.objects[k].concat(dict[k]);
+        }
+        else
+        {
+            this.objects[k] = dict[k];
+        }
+    }
+};
+
+IdlArray.prototype.prevent_multiple_testing = function(name)
+{
+    /** Entry point.  See documentation at beginning of file. */
+    this.members[name].prevent_multiple_testing = true;
+};
+
+IdlArray.prototype.is_json_type = function(type)
+{
+    /**
+     * Checks whether type is a JSON type as per
+     * https://webidl.spec.whatwg.org/#dfn-json-types
+     */
+
+    var idlType = type.idlType;
+
+    if (type.generic == "Promise") { return false; }
+
+    //  nullable and annotated types don't need to be handled separately,
+    //  as webidl2 doesn't represent them wrapped-up (as they're described
+    //  in WebIDL).
+
+    // union and record types
+    if (type.union || type.generic == "record") {
+        return idlType.every(this.is_json_type, this);
+    }
+
+    // sequence types
+    if (type.generic == "sequence" || type.generic == "FrozenArray") {
+        return this.is_json_type(idlType[0]);
+    }
+
+    if (typeof idlType != "string") { throw new Error("Unexpected type " + JSON.stringify(idlType)); }
+
+    switch (idlType)
+    {
+       //  Numeric types
+       case "byte":
+       case "octet":
+       case "short":
+       case "unsigned short":
+       case "long":
+       case "unsigned long":
+       case "long long":
+       case "unsigned long long":
+       case "float":
+       case "double":
+       case "unrestricted float":
+       case "unrestricted double":
+       // boolean
+       case "boolean":
+       // string types
+       case "DOMString":
+       case "ByteString":
+       case "USVString":
+       // object type
+       case "object":
+           return true;
+       case "Error":
+       case "DOMException":
+       case "Int8Array":
+       case "Int16Array":
+       case "Int32Array":
+       case "Uint8Array":
+       case "Uint16Array":
+       case "Uint32Array":
+       case "Uint8ClampedArray":
+       case "BigInt64Array":
+       case "BigUint64Array":
+       case "Float32Array":
+       case "Float64Array":
+       case "ArrayBuffer":
+       case "DataView":
+       case "any":
+           return false;
+       default:
+           var thing = this.members[idlType];
+           if (!thing) { throw new Error("Type " + idlType + " not found"); }
+           if (thing instanceof IdlEnum) { return true; }
+
+           if (thing instanceof IdlTypedef) {
+               return this.is_json_type(thing.idlType);
+           }
+
+           //  dictionaries where all of their members are JSON types
+           if (thing instanceof IdlDictionary) {
+               const map = new Map();
+               for (const dict of thing.get_reverse_inheritance_stack()) {
+                   for (const m of dict.members) {
+                       map.set(m.name, m.idlType);
+                   }
+               }
+               return Array.from(map.values()).every(this.is_json_type, this);
+           }
+
+           //  interface types that have a toJSON operation declared on themselves or
+           //  one of their inherited interfaces.
+           if (thing instanceof IdlInterface) {
+               var base;
+               while (thing)
+               {
+                   if (thing.has_to_json_regular_operation()) { return true; }
+                   var mixins = this.includes[thing.name];
+                   if (mixins) {
+                       mixins = mixins.map(function(id) {
+                           var mixin = this.members[id];
+                           if (!mixin) {
+                               throw new Error("Interface " + id + " not found (implemented by " + thing.name + ")");
+                           }
+                           return mixin;
+                       }, this);
+                       if (mixins.some(function(m) { return m.has_to_json_regular_operation() } )) { return true; }
+                   }
+                   if (!thing.base) { return false; }
+                   base = this.members[thing.base];
+                   if (!base) {
+                       throw new Error("Interface " + thing.base + " not found (inherited by " + thing.name + ")");
+                   }
+                   thing = base;
+               }
+               return false;
+           }
+           return false;
+    }
+};
+
+function exposure_set(object, default_set) {
+    var exposed = object.extAttrs && object.extAttrs.filter(a => a.name === "Exposed");
+    if (exposed && exposed.length > 1) {
+        throw new IdlHarnessError(
+            `Multiple 'Exposed' extended attributes on ${object.name}`);
+    }
+
+    let result = default_set || ["Window"];
+    if (result && !(result instanceof Set)) {
+        result = new Set(result);
+    }
+    if (exposed && exposed.length) {
+        const { rhs } = exposed[0];
+        // Could be a list or a string.
+        const set =
+            rhs.type === "*" ?
+            [ "*" ] :
+            rhs.type === "identifier-list" ?
+            rhs.value.map(id => id.value) :
+            [ rhs.value ];
+        result = new Set(set);
+    }
+    if (result && result.has("*")) {
+        return "*";
+    }
+    if (result && result.has("Worker")) {
+        result.delete("Worker");
+        result.add("DedicatedWorker");
+        result.add("ServiceWorker");
+        result.add("SharedWorker");
+    }
+    return result;
+}
+
+function exposed_in(globals) {
+    if (globals === "*") {
+        return true;
+    }
+    if ('Window' in self) {
+        return globals.has("Window");
+    }
+    if ('DedicatedWorkerGlobalScope' in self &&
+        self instanceof DedicatedWorkerGlobalScope) {
+        return globals.has("DedicatedWorker");
+    }
+    if ('SharedWorkerGlobalScope' in self &&
+        self instanceof SharedWorkerGlobalScope) {
+        return globals.has("SharedWorker");
+    }
+    if ('ServiceWorkerGlobalScope' in self &&
+        self instanceof ServiceWorkerGlobalScope) {
+        return globals.has("ServiceWorker");
+    }
+    if (Object.getPrototypeOf(self) === Object.prototype) {
+        // ShadowRealm - only exposed with `"*"`.
+        return false;
+    }
+    throw new IdlHarnessError("Unexpected global object");
+}
+
+/**
+ * Asserts that the given error message is thrown for the given function.
+ * @param {string|IdlHarnessError} error Expected Error message.
+ * @param {Function} idlArrayFunc Function operating on an IdlArray that should throw.
+ */
+IdlArray.prototype.assert_throws = function(error, idlArrayFunc)
+{
+    try {
+        idlArrayFunc.call(this, this);
+    } catch (e) {
+        if (e instanceof AssertionError) {
+            throw e;
+        }
+        // Assertions for behaviour of the idlharness.js engine.
+        if (error instanceof IdlHarnessError) {
+            error = error.message;
+        }
+        if (e.message !== error) {
+            throw new IdlHarnessError(`${idlArrayFunc} threw "${e}", not the expected IdlHarnessError "${error}"`);
+        }
+        return;
+    }
+    throw new IdlHarnessError(`${idlArrayFunc} did not throw the expected IdlHarnessError`);
+}
+
+IdlArray.prototype.test = function()
+{
+    /** Entry point.  See documentation at beginning of file. */
+
+    // First merge in all partial definitions and interface mixins.
+    this.merge_partials();
+    this.merge_mixins();
+
+    // Assert B defined for A : B
+    for (const member of Object.values(this.members).filter(m => m.base)) {
+        const lhs = member.name;
+        const rhs = member.base;
+        if (!(rhs in this.members)) throw new IdlHarnessError(`${lhs} inherits ${rhs}, but ${rhs} is undefined.`);
+        const lhs_is_interface = this.members[lhs] instanceof IdlInterface;
+        const rhs_is_interface = this.members[rhs] instanceof IdlInterface;
+        if (rhs_is_interface != lhs_is_interface) {
+            if (!lhs_is_interface) throw new IdlHarnessError(`${lhs} inherits ${rhs}, but ${lhs} is not an interface.`);
+            if (!rhs_is_interface) throw new IdlHarnessError(`${lhs} inherits ${rhs}, but ${rhs} is not an interface.`);
+        }
+        // Check for circular dependencies.
+        member.get_reverse_inheritance_stack();
+    }
+
+    Object.getOwnPropertyNames(this.members).forEach(function(memberName) {
+        var member = this.members[memberName];
+        if (!(member instanceof IdlInterface)) {
+            return;
+        }
+
+        var globals = exposure_set(member);
+        member.exposed = exposed_in(globals);
+        member.exposureSet = globals;
+    }.bind(this));
+
+    // Now run test() on every member, and test_object() for every object.
+    for (var name in this.members)
+    {
+        this.members[name].test();
+        if (name in this.objects)
+        {
+            const objects = this.objects[name];
+            if (!objects || !Array.isArray(objects)) {
+                throw new IdlHarnessError(`Invalid or empty objects for member ${name}`);
+            }
+            objects.forEach(function(str)
+            {
+                if (!this.members[name] || !(this.members[name] instanceof IdlInterface)) {
+                    throw new IdlHarnessError(`Invalid object member name ${name}`);
+                }
+                this.members[name].test_object(str);
+            }.bind(this));
+        }
+    }
+};
+
+IdlArray.prototype.merge_partials = function()
+{
+    const testedPartials = new Map();
+    this.partials.forEach(function(parsed_idl)
+    {
+        const originalExists = parsed_idl.name in this.members
+            && (this.members[parsed_idl.name] instanceof IdlInterface
+                || this.members[parsed_idl.name] instanceof IdlDictionary
+                || this.members[parsed_idl.name] instanceof IdlNamespace);
+
+        // Ensure unique test name in case of multiple partials.
+        let partialTestName = parsed_idl.name;
+        let partialTestCount = 1;
+        if (testedPartials.has(parsed_idl.name)) {
+            partialTestCount += testedPartials.get(parsed_idl.name);
+            partialTestName = `${partialTestName}[${partialTestCount}]`;
+        }
+        testedPartials.set(parsed_idl.name, partialTestCount);
+
+        if (!parsed_idl.untested) {
+            test(function () {
+                assert_true(originalExists, `Original ${parsed_idl.type} should be defined`);
+
+                var expected;
+                switch (parsed_idl.type) {
+                    case 'dictionary': expected = IdlDictionary; break;
+                    case 'namespace': expected = IdlNamespace; break;
+                    case 'interface':
+                    case 'interface mixin':
+                    default:
+                        expected = IdlInterface; break;
+                }
+                assert_true(
+                    expected.prototype.isPrototypeOf(this.members[parsed_idl.name]),
+                    `Original ${parsed_idl.name} definition should have type ${parsed_idl.type}`);
+            }.bind(this), `Partial ${parsed_idl.type} ${partialTestName}: original ${parsed_idl.type} defined`);
+        }
+        if (!originalExists) {
+            // Not good.. but keep calm and carry on.
+            return;
+        }
+
+        if (parsed_idl.extAttrs)
+        {
+            // Special-case "Exposed". Must be a subset of original interface's exposure.
+            // Exposed on a partial is the equivalent of having the same Exposed on all nested members.
+            // See https://github.com/heycam/webidl/issues/154 for discrepency between Exposed and
+            // other extended attributes on partial interfaces.
+            const exposureAttr = parsed_idl.extAttrs.find(a => a.name === "Exposed");
+            if (exposureAttr) {
+                if (!parsed_idl.untested) {
+                    test(function () {
+                        const partialExposure = exposure_set(parsed_idl);
+                        const memberExposure = exposure_set(this.members[parsed_idl.name]);
+                        if (memberExposure === "*") {
+                            return;
+                        }
+                        if (partialExposure === "*") {
+                            throw new IdlHarnessError(
+                                `Partial ${parsed_idl.name} ${parsed_idl.type} is exposed everywhere, the original ${parsed_idl.type} is not.`);
+                        }
+                        partialExposure.forEach(name => {
+                            if (!memberExposure || !memberExposure.has(name)) {
+                                throw new IdlHarnessError(
+                                    `Partial ${parsed_idl.name} ${parsed_idl.type} is exposed to '${name}', the original ${parsed_idl.type} is not.`);
+                            }
+                        });
+                    }.bind(this), `Partial ${parsed_idl.type} ${partialTestName}: valid exposure set`);
+                }
+                parsed_idl.members.forEach(function (member) {
+                    member.extAttrs.push(exposureAttr);
+                }.bind(this));
+            }
+
+            parsed_idl.extAttrs.forEach(function(extAttr)
+            {
+                // "Exposed" already handled above.
+                if (extAttr.name === "Exposed") {
+                    return;
+                }
+                this.members[parsed_idl.name].extAttrs.push(extAttr);
+            }.bind(this));
+        }
+        if (parsed_idl.members.length) {
+            test(function () {
+                var clash = parsed_idl.members.find(function(member) {
+                    return this.members[parsed_idl.name].members.find(function(m) {
+                        return this.are_duplicate_members(m, member);
+                    }.bind(this));
+                }.bind(this));
+                parsed_idl.members.forEach(function(member)
+                {
+                    this.members[parsed_idl.name].members.push(new IdlInterfaceMember(member));
+                }.bind(this));
+                assert_true(!clash, "member " + (clash && clash.name) + " is unique");
+            }.bind(this), `Partial ${parsed_idl.type} ${partialTestName}: member names are unique`);
+        }
+    }.bind(this));
+    this.partials = [];
+}
+
+IdlArray.prototype.merge_mixins = function()
+{
+    for (const parsed_idl of this.includes)
+    {
+        const lhs = parsed_idl.target;
+        const rhs = parsed_idl.includes;
+
+        var errStr = lhs + " includes " + rhs + ", but ";
+        if (!(lhs in this.members)) throw errStr + lhs + " is undefined.";
+        if (!(this.members[lhs] instanceof IdlInterface)) throw errStr + lhs + " is not an interface.";
+        if (!(rhs in this.members)) throw errStr + rhs + " is undefined.";
+        if (!(this.members[rhs] instanceof IdlInterface)) throw errStr + rhs + " is not an interface.";
+
+        if (this.members[rhs].members.length) {
+            test(function () {
+                var clash = this.members[rhs].members.find(function(member) {
+                    return this.members[lhs].members.find(function(m) {
+                        return this.are_duplicate_members(m, member);
+                    }.bind(this));
+                }.bind(this));
+                this.members[rhs].members.forEach(function(member) {
+                    assert_true(
+                        this.members[lhs].members.every(m => !this.are_duplicate_members(m, member)),
+                        "member " + member.name + " is unique");
+                    this.members[lhs].members.push(new IdlInterfaceMember(member));
+                }.bind(this));
+                assert_true(!clash, "member " + (clash && clash.name) + " is unique");
+            }.bind(this), lhs + " includes " + rhs + ": member names are unique");
+        }
+    }
+    this.includes = [];
+}
+
+IdlArray.prototype.are_duplicate_members = function(m1, m2) {
+    if (m1.name !== m2.name) {
+        return false;
+    }
+    if (m1.type === 'operation' && m2.type === 'operation'
+        && m1.arguments.length !== m2.arguments.length) {
+        // Method overload. TODO: Deep comparison of arguments.
+        return false;
+    }
+    return true;
+}
+
+IdlArray.prototype.assert_type_is = function(value, type)
+{
+    if (type.idlType in this.members
+    && this.members[type.idlType] instanceof IdlTypedef) {
+        this.assert_type_is(value, this.members[type.idlType].idlType);
+        return;
+    }
+
+    if (type.nullable && value === null)
+    {
+        // This is fine
+        return;
+    }
+
+    if (type.union) {
+        for (var i = 0; i < type.idlType.length; i++) {
+            try {
+                this.assert_type_is(value, type.idlType[i]);
+                // No AssertionError, so we match one type in the union
+                return;
+            } catch(e) {
+                if (e instanceof AssertionError) {
+                    // We didn't match this type, let's try some others
+                    continue;
+                }
+                throw e;
+            }
+        }
+        // TODO: Is there a nice way to list the union's types in the message?
+        assert_true(false, "Attribute has value " + format_value(value)
+                    + " which doesn't match any of the types in the union");
+
+    }
+
+    /**
+     * Helper function that tests that value is an instance of type according
+     * to the rules of WebIDL.  value is any JavaScript value, and type is an
+     * object produced by WebIDLParser.js' "type" production.  That production
+     * is fairly elaborate due to the complexity of WebIDL's types, so it's
+     * best to look at the grammar to figure out what properties it might have.
+     */
+    if (type.idlType == "any")
+    {
+        // No assertions to make
+        return;
+    }
+
+    if (type.array)
+    {
+        // TODO: not supported yet
+        return;
+    }
+
+    if (type.generic === "sequence" || type.generic == "ObservableArray")
+    {
+        assert_true(Array.isArray(value), "should be an Array");
+        if (!value.length)
+        {
+            // Nothing we can do.
+            return;
+        }
+        this.assert_type_is(value[0], type.idlType[0]);
+        return;
+    }
+
+    if (type.generic === "Promise") {
+        assert_true("then" in value, "Attribute with a Promise type should have a then property");
+        // TODO: Ideally, we would check on project fulfillment
+        // that we get the right type
+        // but that would require making the type check async
+        return;
+    }
+
+    if (type.generic === "FrozenArray") {
+        assert_true(Array.isArray(value), "Value should be array");
+        assert_true(Object.isFrozen(value), "Value should be frozen");
+        if (!value.length)
+        {
+            // Nothing we can do.
+            return;
+        }
+        this.assert_type_is(value[0], type.idlType[0]);
+        return;
+    }
+
+    type = Array.isArray(type.idlType) ? type.idlType[0] : type.idlType;
+
+    switch(type)
+    {
+        case "undefined":
+            assert_equals(value, undefined);
+            return;
+
+        case "boolean":
+            assert_equals(typeof value, "boolean");
+            return;
+
+        case "byte":
+            assert_equals(typeof value, "number");
+            assert_equals(value, Math.floor(value), "should be an integer");
+            assert_true(-128 <= value && value <= 127, "byte " + value + " should be in range [-128, 127]");
+            return;
+
+        case "octet":
+            assert_equals(typeof value, "number");
+            assert_equals(value, Math.floor(value), "should be an integer");
+            assert_true(0 <= value && value <= 255, "octet " + value + " should be in range [0, 255]");
+            return;
+
+        case "short":
+            assert_equals(typeof value, "number");
+            assert_equals(value, Math.floor(value), "should be an integer");
+            assert_true(-32768 <= value && value <= 32767, "short " + value + " should be in range [-32768, 32767]");
+            return;
+
+        case "unsigned short":
+            assert_equals(typeof value, "number");
+            assert_equals(value, Math.floor(value), "should be an integer");
+            assert_true(0 <= value && value <= 65535, "unsigned short " + value + " should be in range [0, 65535]");
+            return;
+
+        case "long":
+            assert_equals(typeof value, "number");
+            assert_equals(value, Math.floor(value), "should be an integer");
+            assert_true(-2147483648 <= value && value <= 2147483647, "long " + value + " should be in range [-2147483648, 2147483647]");
+            return;
+
+        case "unsigned long":
+            assert_equals(typeof value, "number");
+            assert_equals(value, Math.floor(value), "should be an integer");
+            assert_true(0 <= value && value <= 4294967295, "unsigned long " + value + " should be in range [0, 4294967295]");
+            return;
+
+        case "long long":
+            assert_equals(typeof value, "number");
+            return;
+
+        case "unsigned long long":
+        case "DOMTimeStamp":
+            assert_equals(typeof value, "number");
+            assert_true(0 <= value, "unsigned long long should be positive");
+            return;
+
+        case "float":
+            assert_equals(typeof value, "number");
+            assert_equals(value, Math.fround(value), "float rounded to 32-bit float should be itself");
+            assert_not_equals(value, Infinity);
+            assert_not_equals(value, -Infinity);
+            assert_not_equals(value, NaN);
+            return;
+
+        case "DOMHighResTimeStamp":
+        case "double":
+            assert_equals(typeof value, "number");
+            assert_not_equals(value, Infinity);
+            assert_not_equals(value, -Infinity);
+            assert_not_equals(value, NaN);
+            return;
+
+        case "unrestricted float":
+            assert_equals(typeof value, "number");
+            assert_equals(value, Math.fround(value), "unrestricted float rounded to 32-bit float should be itself");
+            return;
+
+        case "unrestricted double":
+            assert_equals(typeof value, "number");
+            return;
+
+        case "DOMString":
+            assert_equals(typeof value, "string");
+            return;
+
+        case "ByteString":
+            assert_equals(typeof value, "string");
+            assert_regexp_match(value, /^[\x00-\x7F]*$/);
+            return;
+
+        case "USVString":
+            assert_equals(typeof value, "string");
+            assert_regexp_match(value, /^([\x00-\ud7ff\ue000-\uffff]|[\ud800-\udbff][\udc00-\udfff])*$/);
+            return;
+
+        case "ArrayBufferView":
+            assert_true(ArrayBuffer.isView(value));
+            return;
+
+        case "object":
+            assert_in_array(typeof value, ["object", "function"], "wrong type: not object or function");
+            return;
+    }
+
+    // This is a catch-all for any IDL type name which follows JS class
+    // semantics. This includes some non-interface IDL types (e.g. Int8Array,
+    // Function, ...), as well as any interface types that are not in the IDL
+    // that is fed to the harness. If an IDL type does not follow JS class
+    // semantics then it should go in the switch statement above. If an IDL
+    // type needs full checking, then the test should include it in the IDL it
+    // feeds to the harness.
+    if (!(type in this.members))
+    {
+        assert_true(value instanceof self[type], "wrong type: not a " + type);
+        return;
+    }
+
+    if (this.members[type] instanceof IdlInterface)
+    {
+        // We don't want to run the full
+        // IdlInterface.prototype.test_instance_of, because that could result
+        // in an infinite loop.  TODO: This means we don't have tests for
+        // LegacyNoInterfaceObject interfaces, and we also can't test objects
+        // that come from another self.
+        assert_in_array(typeof value, ["object", "function"], "wrong type: not object or function");
+        if (value instanceof Object
+        && !this.members[type].has_extended_attribute("LegacyNoInterfaceObject")
+        && type in self)
+        {
+            assert_true(value instanceof self[type], "instanceof " + type);
+        }
+    }
+    else if (this.members[type] instanceof IdlEnum)
+    {
+        assert_equals(typeof value, "string");
+    }
+    else if (this.members[type] instanceof IdlDictionary)
+    {
+        // TODO: Test when we actually have something to test this on
+    }
+    else if (this.members[type] instanceof IdlCallback)
+    {
+        assert_equals(typeof value, "function");
+    }
+    else
+    {
+        throw new IdlHarnessError("Type " + type + " isn't an interface, callback or dictionary");
+    }
+};
+
+/// IdlObject ///
+function IdlObject() {}
+IdlObject.prototype.test = function()
+{
+    /**
+     * By default, this does nothing, so no actual tests are run for IdlObjects
+     * that don't define any (e.g., IdlDictionary at the time of this writing).
+     */
+};
+
+IdlObject.prototype.has_extended_attribute = function(name)
+{
+    /**
+     * This is only meaningful for things that support extended attributes,
+     * such as interfaces, exceptions, and members.
+     */
+    return this.extAttrs.some(function(o)
+    {
+        return o.name == name;
+    });
+};
+
+
+/// IdlDictionary ///
+// Used for IdlArray.prototype.assert_type_is
+function IdlDictionary(obj)
+{
+    /**
+     * obj is an object produced by the WebIDLParser.js "dictionary"
+     * production.
+     */
+
+    /** Self-explanatory. */
+    this.name = obj.name;
+
+    /** A back-reference to our IdlArray. */
+    this.array = obj.array;
+
+    /** An array of objects produced by the "dictionaryMember" production. */
+    this.members = obj.members;
+
+    /**
+     * The name (as a string) of the dictionary type we inherit from, or null
+     * if there is none.
+     */
+    this.base = obj.inheritance;
+}
+
+IdlDictionary.prototype = Object.create(IdlObject.prototype);
+
+IdlDictionary.prototype.get_reverse_inheritance_stack = function() {
+    return IdlInterface.prototype.get_reverse_inheritance_stack.call(this);
+};
+
+/// IdlInterface ///
+function IdlInterface(obj, is_callback, is_mixin)
+{
+    /**
+     * obj is an object produced by the WebIDLParser.js "interface" production.
+     */
+
+    /** Self-explanatory. */
+    this.name = obj.name;
+
+    /** A back-reference to our IdlArray. */
+    this.array = obj.array;
+
+    /**
+     * An indicator of whether we should run tests on the interface object and
+     * interface prototype object. Tests on members are controlled by .untested
+     * on each member, not this.
+     */
+    this.untested = obj.untested;
+
+    /** An array of objects produced by the "ExtAttr" production. */
+    this.extAttrs = obj.extAttrs;
+
+    /** An array of IdlInterfaceMembers. */
+    this.members = obj.members.map(function(m){return new IdlInterfaceMember(m); });
+    if (this.has_extended_attribute("LegacyUnforgeable")) {
+        this.members
+            .filter(function(m) { return m.special !== "static" && (m.type == "attribute" || m.type == "operation"); })
+            .forEach(function(m) { return m.isUnforgeable = true; });
+    }
+
+    /**
+     * The name (as a string) of the type we inherit from, or null if there is
+     * none.
+     */
+    this.base = obj.inheritance;
+
+    this._is_callback = is_callback;
+    this._is_mixin = is_mixin;
+}
+IdlInterface.prototype = Object.create(IdlObject.prototype);
+IdlInterface.prototype.is_callback = function()
+{
+    return this._is_callback;
+};
+
+IdlInterface.prototype.is_mixin = function()
+{
+    return this._is_mixin;
+};
+
+IdlInterface.prototype.has_constants = function()
+{
+    return this.members.some(function(member) {
+        return member.type === "const";
+    });
+};
+
+IdlInterface.prototype.get_unscopables = function()
+{
+    return this.members.filter(function(member) {
+        return member.isUnscopable;
+    });
+};
+
+IdlInterface.prototype.is_global = function()
+{
+    return this.extAttrs.some(function(attribute) {
+        return attribute.name === "Global";
+    });
+};
+
+/**
+ * Value of the LegacyNamespace extended attribute, if any.
+ *
+ * https://webidl.spec.whatwg.org/#LegacyNamespace
+ */
+IdlInterface.prototype.get_legacy_namespace = function()
+{
+    var legacyNamespace = this.extAttrs.find(function(attribute) {
+        return attribute.name === "LegacyNamespace";
+    });
+    return legacyNamespace ? legacyNamespace.rhs.value : undefined;
+};
+
+IdlInterface.prototype.get_interface_object_owner = function()
+{
+    var legacyNamespace = this.get_legacy_namespace();
+    return legacyNamespace ? self[legacyNamespace] : self;
+};
+
+IdlInterface.prototype.should_have_interface_object = function()
+{
+    // "For every interface that is exposed in a given ECMAScript global
+    // environment and:
+    // * is a callback interface that has constants declared on it, or
+    // * is a non-callback interface that is not declared with the
+    //   [LegacyNoInterfaceObject] extended attribute,
+    // a corresponding property MUST exist on the ECMAScript global object.
+
+    return this.is_callback() ? this.has_constants() : !this.has_extended_attribute("LegacyNoInterfaceObject");
+};
+
+IdlInterface.prototype.assert_interface_object_exists = function()
+{
+    var owner = this.get_legacy_namespace() || "self";
+    assert_own_property(self[owner], this.name, owner + " does not have own property " + format_value(this.name));
+};
+
+IdlInterface.prototype.get_interface_object = function() {
+    if (!this.should_have_interface_object()) {
+        var reason = this.is_callback() ? "lack of declared constants" : "declared [LegacyNoInterfaceObject] attribute";
+        throw new IdlHarnessError(this.name + " has no interface object due to " + reason);
+    }
+
+    return this.get_interface_object_owner()[this.name];
+};
+
+IdlInterface.prototype.get_qualified_name = function() {
+    // https://webidl.spec.whatwg.org/#qualified-name
+    var legacyNamespace = this.get_legacy_namespace();
+    if (legacyNamespace) {
+        return legacyNamespace + "." + this.name;
+    }
+    return this.name;
+};
+
+IdlInterface.prototype.has_to_json_regular_operation = function() {
+    return this.members.some(function(m) {
+        return m.is_to_json_regular_operation();
+    });
+};
+
+IdlInterface.prototype.has_default_to_json_regular_operation = function() {
+    return this.members.some(function(m) {
+        return m.is_to_json_regular_operation() && m.has_extended_attribute("Default");
+    });
+};
+
+/**
+ * Implementation of https://webidl.spec.whatwg.org/#create-an-inheritance-stack
+ * with the order reversed.
+ *
+ * The order is reversed so that the base class comes first in the list, because
+ * this is what all call sites need.
+ *
+ * So given:
+ *
+ *   A : B {};
+ *   B : C {};
+ *   C {};
+ *
+ * then A.get_reverse_inheritance_stack() returns [C, B, A],
+ * and B.get_reverse_inheritance_stack() returns [C, B].
+ *
+ * Note: as dictionary inheritance is expressed identically by the AST,
+ * this works just as well for getting a stack of inherited dictionaries.
+ */
+IdlInterface.prototype.get_reverse_inheritance_stack = function() {
+    const stack = [this];
+    let idl_interface = this;
+    while (idl_interface.base) {
+        const base = this.array.members[idl_interface.base];
+        if (!base) {
+            throw new Error(idl_interface.type + " " + idl_interface.base + " not found (inherited by " + idl_interface.name + ")");
+        } else if (stack.indexOf(base) > -1) {
+            stack.unshift(base);
+            const dep_chain = stack.map(i => i.name).join(',');
+            throw new IdlHarnessError(`${this.name} has a circular dependency: ${dep_chain}`);
+        }
+        idl_interface = base;
+        stack.unshift(idl_interface);
+    }
+    return stack;
+};
+
+/**
+ * Implementation of
+ * https://webidl.spec.whatwg.org/#default-tojson-operation
+ * for testing purposes.
+ *
+ * Collects the IDL types of the attributes that meet the criteria
+ * for inclusion in the default toJSON operation for easy
+ * comparison with actual value
+ */
+IdlInterface.prototype.default_to_json_operation = function() {
+    const map = new Map()
+    let isDefault = false;
+    for (const I of this.get_reverse_inheritance_stack()) {
+        if (I.has_default_to_json_regular_operation()) {
+            isDefault = true;
+            for (const m of I.members) {
+                if (m.special !== "static" && m.type == "attribute" && I.array.is_json_type(m.idlType)) {
+                    map.set(m.name, m.idlType);
+                }
+            }
+        } else if (I.has_to_json_regular_operation()) {
+            isDefault = false;
+        }
+    }
+    return isDefault ? map : null;
+};
+
+IdlInterface.prototype.test = function()
+{
+    if (this.has_extended_attribute("LegacyNoInterfaceObject") || this.is_mixin())
+    {
+        // No tests to do without an instance.  TODO: We should still be able
+        // to run tests on the prototype object, if we obtain one through some
+        // other means.
+        return;
+    }
+
+    // If the interface object is not exposed, only test that. Members can't be
+    // tested either, but objects could still be tested in |test_object|.
+    if (!this.exposed)
+    {
+        if (!this.untested)
+        {
+            subsetTestByKey(this.name, test, function() {
+                assert_false(this.name in self);
+            }.bind(this), this.name + " interface: existence and properties of interface object");
+        }
+        return;
+    }
+
+    if (!this.untested)
+    {
+        // First test things to do with the exception/interface object and
+        // exception/interface prototype object.
+        this.test_self();
+    }
+    // Then test things to do with its members (constants, fields, attributes,
+    // operations, . . .).  These are run even if .untested is true, because
+    // members might themselves be marked as .untested.  This might happen to
+    // interfaces if the interface itself is untested but a partial interface
+    // that extends it is tested -- then the interface itself and its initial
+    // members will be marked as untested, but the members added by the partial
+    // interface are still tested.
+    this.test_members();
+};
+
+IdlInterface.prototype.constructors = function()
+{
+    return this.members
+        .filter(function(m) { return m.type == "constructor"; });
+}
+
+IdlInterface.prototype.test_self = function()
+{
+    subsetTestByKey(this.name, test, function()
+    {
+        if (!this.should_have_interface_object()) {
+            return;
+        }
+
+        // The name of the property is the identifier of the interface, and its
+        // value is an object called the interface object.
+        // The property has the attributes { [[Writable]]: true,
+        // [[Enumerable]]: false, [[Configurable]]: true }."
+        // TODO: Should we test here that the property is actually writable
+        // etc., or trust getOwnPropertyDescriptor?
+        this.assert_interface_object_exists();
+        var desc = Object.getOwnPropertyDescriptor(this.get_interface_object_owner(), this.name);
+        assert_false("get" in desc, "self's property " + format_value(this.name) + " should not have a getter");
+        assert_false("set" in desc, "self's property " + format_value(this.name) + " should not have a setter");
+        assert_true(desc.writable, "self's property " + format_value(this.name) + " should be writable");
+        assert_false(desc.enumerable, "self's property " + format_value(this.name) + " should not be enumerable");
+        assert_true(desc.configurable, "self's property " + format_value(this.name) + " should be configurable");
+
+        if (this.is_callback()) {
+            // "The internal [[Prototype]] property of an interface object for
+            // a callback interface must be the Function.prototype object."
+            assert_equals(Object.getPrototypeOf(this.get_interface_object()), Function.prototype,
+                          "prototype of self's property " + format_value(this.name) + " is not Object.prototype");
+
+            return;
+        }
+
+        // "The interface object for a given non-callback interface is a
+        // function object."
+        // "If an object is defined to be a function object, then it has
+        // characteristics as follows:"
+
+        // Its [[Prototype]] internal property is otherwise specified (see
+        // below).
+
+        // "* Its [[Get]] internal property is set as described in ECMA-262
+        //    section 9.1.8."
+        // Not much to test for this.
+
+        // "* Its [[Construct]] internal property is set as described in
+        //    ECMA-262 section 19.2.2.3."
+
+        // "* Its @@hasInstance property is set as described in ECMA-262
+        //    section 19.2.3.8, unless otherwise specified."
+        // TODO
+
+        // ES6 (rev 30) 19.1.3.6:
+        // "Else, if O has a [[Call]] internal method, then let builtinTag be
+        // "Function"."
+        assert_class_string(this.get_interface_object(), "Function", "class string of " + this.name);
+
+        // "The [[Prototype]] internal property of an interface object for a
+        // non-callback interface is determined as follows:"
+        var prototype = Object.getPrototypeOf(this.get_interface_object());
+        if (this.base) {
+            // "* If the interface inherits from some other interface, the
+            //    value of [[Prototype]] is the interface object for that other
+            //    interface."
+            var inherited_interface = this.array.members[this.base];
+            if (!inherited_interface.has_extended_attribute("LegacyNoInterfaceObject")) {
+                inherited_interface.assert_interface_object_exists();
+                assert_equals(prototype, inherited_interface.get_interface_object(),
+                              'prototype of ' + this.name + ' is not ' +
+                              this.base);
+            }
+        } else {
+            // "If the interface doesn't inherit from any other interface, the
+            // value of [[Prototype]] is %FunctionPrototype% ([ECMA-262],
+            // section 6.1.7.4)."
+            assert_equals(prototype, Function.prototype,
+                          "prototype of self's property " + format_value(this.name) + " is not Function.prototype");
+        }
+
+        // Always test for [[Construct]]:
+        // https://github.com/heycam/webidl/issues/698
+        assert_true(isConstructor(this.get_interface_object()), "interface object must pass IsConstructor check");
+
+        var interface_object = this.get_interface_object();
+        assert_throws_js(globalOf(interface_object).TypeError, function() {
+            interface_object();
+        }, "interface object didn't throw TypeError when called as a function");
+
+        if (!this.constructors().length) {
+            assert_throws_js(globalOf(interface_object).TypeError, function() {
+                new interface_object();
+            }, "interface object didn't throw TypeError when called as a constructor");
+        }
+    }.bind(this), this.name + " interface: existence and properties of interface object");
+
+    if (this.should_have_interface_object() && !this.is_callback()) {
+        subsetTestByKey(this.name, test, function() {
+            // This function tests WebIDL as of 2014-10-25.
+            // https://webidl.spec.whatwg.org/#es-interface-call
+
+            this.assert_interface_object_exists();
+
+            // "Interface objects for non-callback interfaces MUST have a
+            // property named “length” with attributes { [[Writable]]: false,
+            // [[Enumerable]]: false, [[Configurable]]: true } whose value is
+            // a Number."
+            assert_own_property(this.get_interface_object(), "length");
+            var desc = Object.getOwnPropertyDescriptor(this.get_interface_object(), "length");
+            assert_false("get" in desc, this.name + ".length should not have a getter");
+            assert_false("set" in desc, this.name + ".length should not have a setter");
+            assert_false(desc.writable, this.name + ".length should not be writable");
+            assert_false(desc.enumerable, this.name + ".length should not be enumerable");
+            assert_true(desc.configurable, this.name + ".length should be configurable");
+
+            var constructors = this.constructors();
+            var expected_length = minOverloadLength(constructors);
+            assert_equals(this.get_interface_object().length, expected_length, "wrong value for " + this.name + ".length");
+        }.bind(this), this.name + " interface object length");
+    }
+
+    if (this.should_have_interface_object()) {
+        subsetTestByKey(this.name, test, function() {
+            // This function tests WebIDL as of 2015-11-17.
+            // https://webidl.spec.whatwg.org/#interface-object
+
+            this.assert_interface_object_exists();
+
+            // "All interface objects must have a property named “name” with
+            // attributes { [[Writable]]: false, [[Enumerable]]: false,
+            // [[Configurable]]: true } whose value is the identifier of the
+            // corresponding interface."
+
+            assert_own_property(this.get_interface_object(), "name");
+            var desc = Object.getOwnPropertyDescriptor(this.get_interface_object(), "name");
+            assert_false("get" in desc, this.name + ".name should not have a getter");
+            assert_false("set" in desc, this.name + ".name should not have a setter");
+            assert_false(desc.writable, this.name + ".name should not be writable");
+            assert_false(desc.enumerable, this.name + ".name should not be enumerable");
+            assert_true(desc.configurable, this.name + ".name should be configurable");
+            assert_equals(this.get_interface_object().name, this.name, "wrong value for " + this.name + ".name");
+        }.bind(this), this.name + " interface object name");
+    }
+
+
+    if (this.has_extended_attribute("LegacyWindowAlias")) {
+        subsetTestByKey(this.name, test, function()
+        {
+            var aliasAttrs = this.extAttrs.filter(function(o) { return o.name === "LegacyWindowAlias"; });
+            if (aliasAttrs.length > 1) {
+                throw new IdlHarnessError("Invalid IDL: multiple LegacyWindowAlias extended attributes on " + this.name);
+            }
+            if (this.is_callback()) {
+                throw new IdlHarnessError("Invalid IDL: LegacyWindowAlias extended attribute on non-interface " + this.name);
+            }
+            if (!(this.exposureSet === "*" || this.exposureSet.has("Window"))) {
+                throw new IdlHarnessError("Invalid IDL: LegacyWindowAlias extended attribute on " + this.name + " which is not exposed in Window");
+            }
+            // TODO: when testing of [LegacyNoInterfaceObject] interfaces is supported,
+            // check that it's not specified together with LegacyWindowAlias.
+
+            // TODO: maybe check that [LegacyWindowAlias] is not specified on a partial interface.
+
+            var rhs = aliasAttrs[0].rhs;
+            if (!rhs) {
+                throw new IdlHarnessError("Invalid IDL: LegacyWindowAlias extended attribute on " + this.name + " without identifier");
+            }
+            var aliases;
+            if (rhs.type === "identifier-list") {
+                aliases = rhs.value.map(id => id.value);
+            } else { // rhs.type === identifier
+                aliases = [ rhs.value ];
+            }
+
+            // OK now actually check the aliases...
+            var alias;
+            if (exposed_in(exposure_set(this, this.exposureSet)) && 'document' in self) {
+                for (alias of aliases) {
+                    assert_true(alias in self, alias + " should exist");
+                    assert_equals(self[alias], this.get_interface_object(), "self." + alias + " should be the same value as self." + this.get_qualified_name());
+                    var desc = Object.getOwnPropertyDescriptor(self, alias);
+                    assert_equals(desc.value, this.get_interface_object(), "wrong value in " + alias + " property descriptor");
+                    assert_true(desc.writable, alias + " should be writable");
+                    assert_false(desc.enumerable, alias + " should not be enumerable");
+                    assert_true(desc.configurable, alias + " should be configurable");
+                    assert_false('get' in desc, alias + " should not have a getter");
+                    assert_false('set' in desc, alias + " should not have a setter");
+                }
+            } else {
+                for (alias of aliases) {
+                    assert_false(alias in self, alias + " should not exist");
+                }
+            }
+
+        }.bind(this), this.name + " interface: legacy window alias");
+    }
+
+    if (this.has_extended_attribute("LegacyFactoryFunction")) {
+        var constructors = this.extAttrs
+            .filter(function(attr) { return attr.name == "LegacyFactoryFunction"; });
+        if (constructors.length !== 1) {
+            throw new IdlHarnessError("Internal error: missing support for multiple LegacyFactoryFunction extended attributes");
+        }
+        var constructor = constructors[0];
+        var min_length = minOverloadLength([constructor]);
+
+        subsetTestByKey(this.name, test, function()
+        {
+            // This function tests WebIDL as of 2019-01-14.
+
+            // "for every [LegacyFactoryFunction] extended attribute on an exposed
+            // interface, a corresponding property must exist on the ECMAScript
+            // global object. The name of the property is the
+            // [LegacyFactoryFunction]'s identifier, and its value is an object
+            // called a named constructor, ... . The property has the attributes
+            // { [[Writable]]: true, [[Enumerable]]: false,
+            // [[Configurable]]: true }."
+            var name = constructor.rhs.value;
+            assert_own_property(self, name);
+            var desc = Object.getOwnPropertyDescriptor(self, name);
+            assert_equals(desc.value, self[name], "wrong value in " + name + " property descriptor");
+            assert_true(desc.writable, name + " should be writable");
+            assert_false(desc.enumerable, name + " should not be enumerable");
+            assert_true(desc.configurable, name + " should be configurable");
+            assert_false("get" in desc, name + " should not have a getter");
+            assert_false("set" in desc, name + " should not have a setter");
+        }.bind(this), this.name + " interface: named constructor");
+
+        subsetTestByKey(this.name, test, function()
+        {
+            // This function tests WebIDL as of 2019-01-14.
+
+            // "2. Let F be ! CreateBuiltinFunction(realm, steps,
+            //     realm.[[Intrinsics]].[[%FunctionPrototype%]])."
+            var name = constructor.rhs.value;
+            var value = self[name];
+            assert_equals(typeof value, "function", "type of value in " + name + " property descriptor");
+            assert_not_equals(value, this.get_interface_object(), "wrong value in " + name + " property descriptor");
+            assert_equals(Object.getPrototypeOf(value), Function.prototype, "wrong value for " + name + "'s prototype");
+        }.bind(this), this.name + " interface: named constructor object");
+
+        subsetTestByKey(this.name, test, function()
+        {
+            // This function tests WebIDL as of 2019-01-14.
+
+            // "7. Let proto be the interface prototype object of interface I
+            //     in realm.
+            // "8. Perform ! DefinePropertyOrThrow(F, "prototype",
+            //     PropertyDescriptor{
+            //         [[Value]]: proto, [[Writable]]: false,
+            //         [[Enumerable]]: false, [[Configurable]]: false
+            //     })."
+            var name = constructor.rhs.value;
+            var expected = this.get_interface_object().prototype;
+            var desc = Object.getOwnPropertyDescriptor(self[name], "prototype");
+            assert_equals(desc.value, expected, "wrong value for " + name + ".prototype");
+            assert_false(desc.writable, "prototype should not be writable");
+            assert_false(desc.enumerable, "prototype should not be enumerable");
+            assert_false(desc.configurable, "prototype should not be configurable");
+            assert_false("get" in desc, "prototype should not have a getter");
+            assert_false("set" in desc, "prototype should not have a setter");
+        }.bind(this), this.name + " interface: named constructor prototype property");
+
+        subsetTestByKey(this.name, test, function()
+        {
+            // This function tests WebIDL as of 2019-01-14.
+
+            // "3. Perform ! SetFunctionName(F, id)."
+            var name = constructor.rhs.value;
+            var desc = Object.getOwnPropertyDescriptor(self[name], "name");
+            assert_equals(desc.value, name, "wrong value for " + name + ".name");
+            assert_false(desc.writable, "name should not be writable");
+            assert_false(desc.enumerable, "name should not be enumerable");
+            assert_true(desc.configurable, "name should be configurable");
+            assert_false("get" in desc, "name should not have a getter");
+            assert_false("set" in desc, "name should not have a setter");
+        }.bind(this), this.name + " interface: named constructor name");
+
+        subsetTestByKey(this.name, test, function()
+        {
+            // This function tests WebIDL as of 2019-01-14.
+
+            // "4. Initialize S to the effective overload set for constructors
+            //     with identifier id on interface I and with argument count 0.
+            // "5. Let length be the length of the shortest argument list of
+            //     the entries in S.
+            // "6. Perform ! SetFunctionLength(F, length)."
+            var name = constructor.rhs.value;
+            var desc = Object.getOwnPropertyDescriptor(self[name], "length");
+            assert_equals(desc.value, min_length, "wrong value for " + name + ".length");
+            assert_false(desc.writable, "length should not be writable");
+            assert_false(desc.enumerable, "length should not be enumerable");
+            assert_true(desc.configurable, "length should be configurable");
+            assert_false("get" in desc, "length should not have a getter");
+            assert_false("set" in desc, "length should not have a setter");
+        }.bind(this), this.name + " interface: named constructor length");
+
+        subsetTestByKey(this.name, test, function()
+        {
+            // This function tests WebIDL as of 2019-01-14.
+
+            // "1. Let steps be the following steps:
+            // "    1. If NewTarget is undefined, then throw a TypeError."
+            var name = constructor.rhs.value;
+            var args = constructor.arguments.map(function(arg) {
+                return create_suitable_object(arg.idlType);
+            });
+            assert_throws_js(globalOf(self[name]).TypeError, function() {
+                self[name](...args);
+            }.bind(this));
+        }.bind(this), this.name + " interface: named constructor without 'new'");
+    }
+
+    subsetTestByKey(this.name, test, function()
+    {
+        // This function tests WebIDL as of 2015-01-21.
+        // https://webidl.spec.whatwg.org/#interface-object
+
+        if (!this.should_have_interface_object()) {
+            return;
+        }
+
+        this.assert_interface_object_exists();
+
+        if (this.is_callback()) {
+            assert_false("prototype" in this.get_interface_object(),
+                         this.name + ' should not have a "prototype" property');
+            return;
+        }
+
+        // "An interface object for a non-callback interface must have a
+        // property named “prototype” with attributes { [[Writable]]: false,
+        // [[Enumerable]]: false, [[Configurable]]: false } whose value is an
+        // object called the interface prototype object. This object has
+        // properties that correspond to the regular attributes and regular
+        // operations defined on the interface, and is described in more detail
+        // in section 4.5.4 below."
+        assert_own_property(this.get_interface_object(), "prototype",
+                            'interface "' + this.name + '" does not have own property "prototype"');
+        var desc = Object.getOwnPropertyDescriptor(this.get_interface_object(), "prototype");
+        assert_false("get" in desc, this.name + ".prototype should not have a getter");
+        assert_false("set" in desc, this.name + ".prototype should not have a setter");
+        assert_false(desc.writable, this.name + ".prototype should not be writable");
+        assert_false(desc.enumerable, this.name + ".prototype should not be enumerable");
+        assert_false(desc.configurable, this.name + ".prototype should not be configurable");
+
+        // Next, test that the [[Prototype]] of the interface prototype object
+        // is correct. (This is made somewhat difficult by the existence of
+        // [LegacyNoInterfaceObject].)
+        // TODO: Aryeh thinks there's at least other place in this file where
+        //       we try to figure out if an interface prototype object is
+        //       correct. Consolidate that code.
+
+        // "The interface prototype object for a given interface A must have an
+        // internal [[Prototype]] property whose value is returned from the
+        // following steps:
+        // "If A is declared with the [Global] extended
+        // attribute, and A supports named properties, then return the named
+        // properties object for A, as defined in §3.6.4 Named properties
+        // object.
+        // "Otherwise, if A is declared to inherit from another interface, then
+        // return the interface prototype object for the inherited interface.
+        // "Otherwise, return %ObjectPrototype%.
+        //
+        // "In the ECMAScript binding, the DOMException type has some additional
+        // requirements:
+        //
+        //     "Unlike normal interface types, the interface prototype object
+        //     for DOMException must have as its [[Prototype]] the intrinsic
+        //     object %ErrorPrototype%."
+        //
+        if (this.name === "Window") {
+            assert_class_string(Object.getPrototypeOf(this.get_interface_object().prototype),
+                                'WindowProperties',
+                                'Class name for prototype of Window' +
+                                '.prototype is not "WindowProperties"');
+        } else {
+            var inherit_interface, inherit_interface_interface_object;
+            if (this.base) {
+                inherit_interface = this.base;
+                var parent = this.array.members[inherit_interface];
+                if (!parent.has_extended_attribute("LegacyNoInterfaceObject")) {
+                    parent.assert_interface_object_exists();
+                    inherit_interface_interface_object = parent.get_interface_object();
+                }
+            } else if (this.name === "DOMException") {
+                inherit_interface = 'Error';
+                inherit_interface_interface_object = self.Error;
+            } else {
+                inherit_interface = 'Object';
+                inherit_interface_interface_object = self.Object;
+            }
+            if (inherit_interface_interface_object) {
+                assert_not_equals(inherit_interface_interface_object, undefined,
+                                  'should inherit from ' + inherit_interface + ', but there is no such property');
+                assert_own_property(inherit_interface_interface_object, 'prototype',
+                                    'should inherit from ' + inherit_interface + ', but that object has no "prototype" property');
+                assert_equals(Object.getPrototypeOf(this.get_interface_object().prototype),
+                              inherit_interface_interface_object.prototype,
+                              'prototype of ' + this.name + '.prototype is not ' + inherit_interface + '.prototype');
+            } else {
+                // We can't test that we get the correct object, because this is the
+                // only way to get our hands on it. We only test that its class
+                // string, at least, is correct.
+                assert_class_string(Object.getPrototypeOf(this.get_interface_object().prototype),
+                                    inherit_interface + 'Prototype',
+                                    'Class name for prototype of ' + this.name +
+                                    '.prototype is not "' + inherit_interface + 'Prototype"');
+            }
+        }
+
+        // "The class string of an interface prototype object is the
+        // concatenation of the interface’s qualified identifier and the string
+        // “Prototype”."
+
+        // Skip these tests for now due to a specification issue about
+        // prototype name.
+        // https://www.w3.org/Bugs/Public/show_bug.cgi?id=28244
+
+        // assert_class_string(this.get_interface_object().prototype, this.get_qualified_name() + "Prototype",
+        //                     "class string of " + this.name + ".prototype");
+
+        // String() should end up calling {}.toString if nothing defines a
+        // stringifier.
+        if (!this.has_stringifier()) {
+            // assert_equals(String(this.get_interface_object().prototype), "[object " + this.get_qualified_name() + "Prototype]",
+            //         "String(" + this.name + ".prototype)");
+        }
+    }.bind(this), this.name + " interface: existence and properties of interface prototype object");
+
+    // "If the interface is declared with the [Global]
+    // extended attribute, or the interface is in the set of inherited
+    // interfaces for any other interface that is declared with one of these
+    // attributes, then the interface prototype object must be an immutable
+    // prototype exotic object."
+    // https://webidl.spec.whatwg.org/#interface-prototype-object
+    if (this.is_global()) {
+        this.test_immutable_prototype("interface prototype object", this.get_interface_object().prototype);
+    }
+
+    subsetTestByKey(this.name, test, function()
+    {
+        if (!this.should_have_interface_object()) {
+            return;
+        }
+
+        this.assert_interface_object_exists();
+
+        if (this.is_callback()) {
+            assert_false("prototype" in this.get_interface_object(),
+                         this.name + ' should not have a "prototype" property');
+            return;
+        }
+
+        assert_own_property(this.get_interface_object(), "prototype",
+                            'interface "' + this.name + '" does not have own property "prototype"');
+
+        // "If the [LegacyNoInterfaceObject] extended attribute was not specified
+        // on the interface, then the interface prototype object must also have a
+        // property named “constructor” with attributes { [[Writable]]: true,
+        // [[Enumerable]]: false, [[Configurable]]: true } whose value is a
+        // reference to the interface object for the interface."
+        assert_own_property(this.get_interface_object().prototype, "constructor",
+                            this.name + '.prototype does not have own property "constructor"');
+        var desc = Object.getOwnPropertyDescriptor(this.get_interface_object().prototype, "constructor");
+        assert_false("get" in desc, this.name + ".prototype.constructor should not have a getter");
+        assert_false("set" in desc, this.name + ".prototype.constructor should not have a setter");
+        assert_true(desc.writable, this.name + ".prototype.constructor should be writable");
+        assert_false(desc.enumerable, this.name + ".prototype.constructor should not be enumerable");
+        assert_true(desc.configurable, this.name + ".prototype.constructor should be configurable");
+        assert_equals(this.get_interface_object().prototype.constructor, this.get_interface_object(),
+                      this.name + '.prototype.constructor is not the same object as ' + this.name);
+    }.bind(this), this.name + ' interface: existence and properties of interface prototype object\'s "constructor" property');
+
+
+    subsetTestByKey(this.name, test, function()
+    {
+        if (!this.should_have_interface_object()) {
+            return;
+        }
+
+        this.assert_interface_object_exists();
+
+        if (this.is_callback()) {
+            assert_false("prototype" in this.get_interface_object(),
+                         this.name + ' should not have a "prototype" property');
+            return;
+        }
+
+        assert_own_property(this.get_interface_object(), "prototype",
+                            'interface "' + this.name + '" does not have own property "prototype"');
+
+        // If the interface has any member declared with the [Unscopable] extended
+        // attribute, then there must be a property on the interface prototype object
+        // whose name is the @@unscopables symbol, which has the attributes
+        // { [[Writable]]: false, [[Enumerable]]: false, [[Configurable]]: true },
+        // and whose value is an object created as follows...
+        var unscopables = this.get_unscopables().map(m => m.name);
+        var proto = this.get_interface_object().prototype;
+        if (unscopables.length != 0) {
+            assert_own_property(
+                proto, Symbol.unscopables,
+                this.name + '.prototype should have an @@unscopables property');
+            var desc = Object.getOwnPropertyDescriptor(proto, Symbol.unscopables);
+            assert_false("get" in desc,
+                         this.name + ".prototype[Symbol.unscopables] should not have a getter");
+            assert_false("set" in desc, this.name + ".prototype[Symbol.unscopables] should not have a setter");
+            assert_false(desc.writable, this.name + ".prototype[Symbol.unscopables] should not be writable");
+            assert_false(desc.enumerable, this.name + ".prototype[Symbol.unscopables] should not be enumerable");
+            assert_true(desc.configurable, this.name + ".prototype[Symbol.unscopables] should be configurable");
+            assert_equals(desc.value, proto[Symbol.unscopables],
+                          this.name + '.prototype[Symbol.unscopables] should be in the descriptor');
+            assert_equals(typeof desc.value, "object",
+                          this.name + '.prototype[Symbol.unscopables] should be an object');
+            assert_equals(Object.getPrototypeOf(desc.value), null,
+                          this.name + '.prototype[Symbol.unscopables] should have a null prototype');
+            assert_equals(Object.getOwnPropertySymbols(desc.value).length,
+                          0,
+                          this.name + '.prototype[Symbol.unscopables] should have the right number of symbol-named properties');
+
+            // Check that we do not have _extra_ unscopables.  Checking that we
+            // have all the ones we should will happen in the per-member tests.
+            var observed = Object.getOwnPropertyNames(desc.value);
+            for (var prop of observed) {
+                assert_not_equals(unscopables.indexOf(prop),
+                                  -1,
+                                  this.name + '.prototype[Symbol.unscopables] has unexpected property "' + prop + '"');
+            }
+        } else {
+            assert_equals(Object.getOwnPropertyDescriptor(this.get_interface_object().prototype, Symbol.unscopables),
+                          undefined,
+                          this.name + '.prototype should not have @@unscopables');
+        }
+    }.bind(this), this.name + ' interface: existence and properties of interface prototype object\'s @@unscopables property');
+};
+
+IdlInterface.prototype.test_immutable_prototype = function(type, obj)
+{
+    if (typeof Object.setPrototypeOf !== "function") {
+        return;
+    }
+
+    subsetTestByKey(this.name, test, function(t) {
+        var originalValue = Object.getPrototypeOf(obj);
+        var newValue = Object.create(null);
+
+        t.add_cleanup(function() {
+            try {
+                Object.setPrototypeOf(obj, originalValue);
+            } catch (err) {}
+        });
+
+        assert_throws_js(TypeError, function() {
+            Object.setPrototypeOf(obj, newValue);
+        });
+
+        assert_equals(
+                Object.getPrototypeOf(obj),
+                originalValue,
+                "original value not modified"
+            );
+    }.bind(this), this.name + " interface: internal [[SetPrototypeOf]] method " +
+        "of " + type + " - setting to a new value via Object.setPrototypeOf " +
+        "should throw a TypeError");
+
+    subsetTestByKey(this.name, test, function(t) {
+        var originalValue = Object.getPrototypeOf(obj);
+        var newValue = Object.create(null);
+
+        t.add_cleanup(function() {
+            let setter = Object.getOwnPropertyDescriptor(
+                Object.prototype, '__proto__'
+            ).set;
+
+            try {
+                setter.call(obj, originalValue);
+            } catch (err) {}
+        });
+
+        // We need to find the actual setter for the '__proto__' property, so we
+        // can determine the right global for it.  Walk up the prototype chain
+        // looking for that property until we find it.
+        let setter;
+        {
+            let cur = obj;
+            while (cur) {
+                const desc = Object.getOwnPropertyDescriptor(cur, "__proto__");
+                if (desc) {
+                    setter = desc.set;
+                    break;
+                }
+                cur = Object.getPrototypeOf(cur);
+            }
+        }
+        assert_throws_js(globalOf(setter).TypeError, function() {
+            obj.__proto__ = newValue;
+        });
+
+        assert_equals(
+                Object.getPrototypeOf(obj),
+                originalValue,
+                "original value not modified"
+            );
+    }.bind(this), this.name + " interface: internal [[SetPrototypeOf]] method " +
+        "of " + type + " - setting to a new value via __proto__ " +
+        "should throw a TypeError");
+
+    subsetTestByKey(this.name, test, function(t) {
+        var originalValue = Object.getPrototypeOf(obj);
+        var newValue = Object.create(null);
+
+        t.add_cleanup(function() {
+            try {
+                Reflect.setPrototypeOf(obj, originalValue);
+            } catch (err) {}
+        });
+
+        assert_false(Reflect.setPrototypeOf(obj, newValue));
+
+        assert_equals(
+                Object.getPrototypeOf(obj),
+                originalValue,
+                "original value not modified"
+            );
+    }.bind(this), this.name + " interface: internal [[SetPrototypeOf]] method " +
+        "of " + type + " - setting to a new value via Reflect.setPrototypeOf " +
+        "should return false");
+
+    subsetTestByKey(this.name, test, function() {
+        var originalValue = Object.getPrototypeOf(obj);
+
+        Object.setPrototypeOf(obj, originalValue);
+    }.bind(this), this.name + " interface: internal [[SetPrototypeOf]] method " +
+        "of " + type + " - setting to its original value via Object.setPrototypeOf " +
+        "should not throw");
+
+    subsetTestByKey(this.name, test, function() {
+        var originalValue = Object.getPrototypeOf(obj);
+
+        obj.__proto__ = originalValue;
+    }.bind(this), this.name + " interface: internal [[SetPrototypeOf]] method " +
+        "of " + type + " - setting to its original value via __proto__ " +
+        "should not throw");
+
+    subsetTestByKey(this.name, test, function() {
+        var originalValue = Object.getPrototypeOf(obj);
+
+        assert_true(Reflect.setPrototypeOf(obj, originalValue));
+    }.bind(this), this.name + " interface: internal [[SetPrototypeOf]] method " +
+        "of " + type + " - setting to its original value via Reflect.setPrototypeOf " +
+        "should return true");
+};
+
+IdlInterface.prototype.test_member_const = function(member)
+{
+    if (!this.has_constants()) {
+        throw new IdlHarnessError("Internal error: test_member_const called without any constants");
+    }
+
+    subsetTestByKey(this.name, test, function()
+    {
+        this.assert_interface_object_exists();
+
+        // "For each constant defined on an interface A, there must be
+        // a corresponding property on the interface object, if it
+        // exists."
+        assert_own_property(this.get_interface_object(), member.name);
+        // "The value of the property is that which is obtained by
+        // converting the constant’s IDL value to an ECMAScript
+        // value."
+        assert_equals(this.get_interface_object()[member.name], constValue(member.value),
+                      "property has wrong value");
+        // "The property has attributes { [[Writable]]: false,
+        // [[Enumerable]]: true, [[Configurable]]: false }."
+        var desc = Object.getOwnPropertyDescriptor(this.get_interface_object(), member.name);
+        assert_false("get" in desc, "property should not have a getter");
+        assert_false("set" in desc, "property should not have a setter");
+        assert_false(desc.writable, "property should not be writable");
+        assert_true(desc.enumerable, "property should be enumerable");
+        assert_false(desc.configurable, "property should not be configurable");
+    }.bind(this), this.name + " interface: constant " + member.name + " on interface object");
+
+    // "In addition, a property with the same characteristics must
+    // exist on the interface prototype object."
+    subsetTestByKey(this.name, test, function()
+    {
+        this.assert_interface_object_exists();
+
+        if (this.is_callback()) {
+            assert_false("prototype" in this.get_interface_object(),
+                         this.name + ' should not have a "prototype" property');
+            return;
+        }
+
+        assert_own_property(this.get_interface_object(), "prototype",
+                            'interface "' + this.name + '" does not have own property "prototype"');
+
+        assert_own_property(this.get_interface_object().prototype, member.name);
+        assert_equals(this.get_interface_object().prototype[member.name], constValue(member.value),
+                      "property has wrong value");
+        var desc = Object.getOwnPropertyDescriptor(this.get_interface_object(), member.name);
+        assert_false("get" in desc, "property should not have a getter");
+        assert_false("set" in desc, "property should not have a setter");
+        assert_false(desc.writable, "property should not be writable");
+        assert_true(desc.enumerable, "property should be enumerable");
+        assert_false(desc.configurable, "property should not be configurable");
+    }.bind(this), this.name + " interface: constant " + member.name + " on interface prototype object");
+};
+
+
+IdlInterface.prototype.test_member_attribute = function(member)
+  {
+    if (!shouldRunSubTest(this.name)) {
+        return;
+    }
+    var a_test = subsetTestByKey(this.name, async_test, this.name + " interface: attribute " + member.name);
+    a_test.step(function()
+    {
+        if (!this.should_have_interface_object()) {
+            a_test.done();
+            return;
+        }
+
+        this.assert_interface_object_exists();
+        assert_own_property(this.get_interface_object(), "prototype",
+                            'interface "' + this.name + '" does not have own property "prototype"');
+
+        if (member.special === "static") {
+            assert_own_property(this.get_interface_object(), member.name,
+                "The interface object must have a property " +
+                format_value(member.name));
+            a_test.done();
+            return;
+        }
+
+        this.do_member_unscopable_asserts(member);
+
+        if (this.is_global()) {
+            assert_own_property(self, member.name,
+                "The global object must have a property " +
+                format_value(member.name));
+            assert_false(member.name in this.get_interface_object().prototype,
+                "The prototype object should not have a property " +
+                format_value(member.name));
+
+            var getter = Object.getOwnPropertyDescriptor(self, member.name).get;
+            assert_equals(typeof(getter), "function",
+                          format_value(member.name) + " must have a getter");
+
+            // Try/catch around the get here, since it can legitimately throw.
+            // If it does, we obviously can't check for equality with direct
+            // invocation of the getter.
+            var gotValue;
+            var propVal;
+            try {
+                propVal = self[member.name];
+                gotValue = true;
+            } catch (e) {
+                gotValue = false;
+            }
+            if (gotValue) {
+                assert_equals(propVal, getter.call(undefined),
+                              "Gets on a global should not require an explicit this");
+            }
+
+            // do_interface_attribute_asserts must be the last thing we do,
+            // since it will call done() on a_test.
+            this.do_interface_attribute_asserts(self, member, a_test);
+        } else {
+            assert_true(member.name in this.get_interface_object().prototype,
+                "The prototype object must have a property " +
+                format_value(member.name));
+
+            if (!member.has_extended_attribute("LegacyLenientThis")) {
+                if (member.idlType.generic !== "Promise") {
+                    // this.get_interface_object() returns a thing in our global
+                    assert_throws_js(TypeError, function() {
+                        this.get_interface_object().prototype[member.name];
+                    }.bind(this), "getting property on prototype object must throw TypeError");
+                    // do_interface_attribute_asserts must be the last thing we
+                    // do, since it will call done() on a_test.
+                    this.do_interface_attribute_asserts(this.get_interface_object().prototype, member, a_test);
+                } else {
+                    promise_rejects_js(a_test, TypeError,
+                                    this.get_interface_object().prototype[member.name])
+                        .then(a_test.step_func(function() {
+                            // do_interface_attribute_asserts must be the last
+                            // thing we do, since it will call done() on a_test.
+                            this.do_interface_attribute_asserts(this.get_interface_object().prototype,
+                                                                member, a_test);
+                        }.bind(this)));
+                }
+            } else {
+                assert_equals(this.get_interface_object().prototype[member.name], undefined,
+                              "getting property on prototype object must return undefined");
+              // do_interface_attribute_asserts must be the last thing we do,
+              // since it will call done() on a_test.
+              this.do_interface_attribute_asserts(this.get_interface_object().prototype, member, a_test);
+            }
+        }
+    }.bind(this));
+};
+
+IdlInterface.prototype.test_member_operation = function(member)
+{
+    if (!shouldRunSubTest(this.name)) {
+        return;
+    }
+    var a_test = subsetTestByKey(this.name, async_test, this.name + " interface: operation " + member);
+    a_test.step(function()
+    {
+        // This function tests WebIDL as of 2015-12-29.
+        // https://webidl.spec.whatwg.org/#es-operations
+
+        if (!this.should_have_interface_object()) {
+            a_test.done();
+            return;
+        }
+
+        this.assert_interface_object_exists();
+
+        if (this.is_callback()) {
+            assert_false("prototype" in this.get_interface_object(),
+                         this.name + ' should not have a "prototype" property');
+            a_test.done();
+            return;
+        }
+
+        assert_own_property(this.get_interface_object(), "prototype",
+                            'interface "' + this.name + '" does not have own property "prototype"');
+
+        // "For each unique identifier of an exposed operation defined on the
+        // interface, there must exist a corresponding property, unless the
+        // effective overload set for that identifier and operation and with an
+        // argument count of 0 has no entries."
+
+        // TODO: Consider [Exposed].
+
+        // "The location of the property is determined as follows:"
+        var memberHolderObject;
+        // "* If the operation is static, then the property exists on the
+        //    interface object."
+        if (member.special === "static") {
+            assert_own_property(this.get_interface_object(), member.name,
+                    "interface object missing static operation");
+            memberHolderObject = this.get_interface_object();
+        // "* Otherwise, [...] if the interface was declared with the [Global]
+        //    extended attribute, then the property exists
+        //    on every object that implements the interface."
+        } else if (this.is_global()) {
+            assert_own_property(self, member.name,
+                    "global object missing non-static operation");
+            memberHolderObject = self;
+        // "* Otherwise, the property exists solely on the interface’s
+        //    interface prototype object."
+        } else {
+            assert_own_property(this.get_interface_object().prototype, member.name,
+                    "interface prototype object missing non-static operation");
+            memberHolderObject = this.get_interface_object().prototype;
+        }
+        this.do_member_unscopable_asserts(member);
+        this.do_member_operation_asserts(memberHolderObject, member, a_test);
+    }.bind(this));
+};
+
+IdlInterface.prototype.do_member_unscopable_asserts = function(member)
+{
+    // Check that if the member is unscopable then it's in the
+    // @@unscopables object properly.
+    if (!member.isUnscopable) {
+        return;
+    }
+
+    var unscopables = this.get_interface_object().prototype[Symbol.unscopables];
+    var prop = member.name;
+    var propDesc = Object.getOwnPropertyDescriptor(unscopables, prop);
+    assert_equals(typeof propDesc, "object",
+                  this.name + '.prototype[Symbol.unscopables].' + prop + ' must exist')
+    assert_false("get" in propDesc,
+                 this.name + '.prototype[Symbol.unscopables].' + prop + ' must have no getter');
+    assert_false("set" in propDesc,
+                 this.name + '.prototype[Symbol.unscopables].' + prop + ' must have no setter');
+    assert_true(propDesc.writable,
+                this.name + '.prototype[Symbol.unscopables].' + prop + ' must be writable');
+    assert_true(propDesc.enumerable,
+                this.name + '.prototype[Symbol.unscopables].' + prop + ' must be enumerable');
+    assert_true(propDesc.configurable,
+                this.name + '.prototype[Symbol.unscopables].' + prop + ' must be configurable');
+    assert_equals(propDesc.value, true,
+                  this.name + '.prototype[Symbol.unscopables].' + prop + ' must have the value `true`');
+};
+
+IdlInterface.prototype.do_member_operation_asserts = function(memberHolderObject, member, a_test)
+{
+    var done = a_test.done.bind(a_test);
+    var operationUnforgeable = member.isUnforgeable;
+    var desc = Object.getOwnPropertyDescriptor(memberHolderObject, member.name);
+    // "The property has attributes { [[Writable]]: B,
+    // [[Enumerable]]: true, [[Configurable]]: B }, where B is false if the
+    // operation is unforgeable on the interface, and true otherwise".
+    assert_false("get" in desc, "property should not have a getter");
+    assert_false("set" in desc, "property should not have a setter");
+    assert_equals(desc.writable, !operationUnforgeable,
+                  "property should be writable if and only if not unforgeable");
+    assert_true(desc.enumerable, "property should be enumerable");
+    assert_equals(desc.configurable, !operationUnforgeable,
+                  "property should be configurable if and only if not unforgeable");
+    // "The value of the property is a Function object whose
+    // behavior is as follows . . ."
+    assert_equals(typeof memberHolderObject[member.name], "function",
+                  "property must be a function");
+
+    const operationOverloads = this.members.filter(function(m) {
+        return m.type == "operation" && m.name == member.name &&
+            (m.special === "static") === (member.special === "static");
+    });
+    assert_equals(
+        memberHolderObject[member.name].length,
+        minOverloadLength(operationOverloads),
+        "property has wrong .length");
+    assert_equals(
+        memberHolderObject[member.name].name,
+        member.name,
+        "property has wrong .name");
+
+    // Make some suitable arguments
+    var args = member.arguments.map(function(arg) {
+        return create_suitable_object(arg.idlType);
+    });
+
+    // "Let O be a value determined as follows:
+    // ". . .
+    // "Otherwise, throw a TypeError."
+    // This should be hit if the operation is not static, there is
+    // no [ImplicitThis] attribute, and the this value is null.
+    //
+    // TODO: We currently ignore the [ImplicitThis] case.  Except we manually
+    // check for globals, since otherwise we'll invoke window.close().  And we
+    // have to skip this test for anything that on the proto chain of "self",
+    // since that does in fact have implicit-this behavior.
+    if (member.special !== "static") {
+        var cb;
+        if (!this.is_global() &&
+            memberHolderObject[member.name] != self[member.name])
+        {
+            cb = awaitNCallbacks(2, done);
+            throwOrReject(a_test, member, memberHolderObject[member.name], null, args,
+                          "calling operation with this = null didn't throw TypeError", cb);
+        } else {
+            cb = awaitNCallbacks(1, done);
+        }
+
+        // ". . . If O is not null and is also not a platform object
+        // that implements interface I, throw a TypeError."
+        //
+        // TODO: Test a platform object that implements some other
+        // interface.  (Have to be sure to get inheritance right.)
+        throwOrReject(a_test, member, memberHolderObject[member.name], {}, args,
+                      "calling operation with this = {} didn't throw TypeError", cb);
+    } else {
+        done();
+    }
+}
+
+IdlInterface.prototype.test_to_json_operation = function(desc, memberHolderObject, member) {
+    var instanceName = memberHolderObject && memberHolderObject.constructor.name
+        || member.name + " object";
+    if (member.has_extended_attribute("Default")) {
+        subsetTestByKey(this.name, test, function() {
+            var map = this.default_to_json_operation();
+            var json = memberHolderObject.toJSON();
+            map.forEach(function(type, k) {
+                assert_true(k in json, "property " + JSON.stringify(k) + " should be present in the output of " + this.name + ".prototype.toJSON()");
+                var descriptor = Object.getOwnPropertyDescriptor(json, k);
+                assert_true(descriptor.writable, "property " + k + " should be writable");
+                assert_true(descriptor.configurable, "property " + k + " should be configurable");
+                assert_true(descriptor.enumerable, "property " + k + " should be enumerable");
+                this.array.assert_type_is(json[k], type);
+                delete json[k];
+            }, this);
+        }.bind(this), this.name + " interface: default toJSON operation on " + desc);
+    } else {
+        subsetTestByKey(this.name, test, function() {
+            assert_true(this.array.is_json_type(member.idlType), JSON.stringify(member.idlType) + " is not an appropriate return value for the toJSON operation of " + instanceName);
+            this.array.assert_type_is(memberHolderObject.toJSON(), member.idlType);
+        }.bind(this), this.name + " interface: toJSON operation on " + desc);
+    }
+};
+
+IdlInterface.prototype.test_member_maplike = function(member) {
+    subsetTestByKey(this.name, test, () => {
+        const proto = this.get_interface_object().prototype;
+
+        const methods = [
+            ["entries", 0],
+            ["keys", 0],
+            ["values", 0],
+            ["forEach", 1],
+            ["get", 1],
+            ["has", 1]
+        ];
+        if (!member.readonly) {
+            methods.push(
+                ["set", 2],
+                ["delete", 1],
+                ["clear", 0]
+            );
+        }
+
+        for (const [name, length] of methods) {
+            const desc = Object.getOwnPropertyDescriptor(proto, name);
+            assert_equals(typeof desc.value, "function", `${name} should be a function`);
+            assert_equals(desc.enumerable, true, `${name} enumerable`);
+            assert_equals(desc.configurable, true, `${name} configurable`);
+            assert_equals(desc.writable, true, `${name} writable`);
+            assert_equals(desc.value.length, length, `${name} function object length should be ${length}`);
+            assert_equals(desc.value.name, name, `${name} function object should have the right name`);
+        }
+
+        const iteratorDesc = Object.getOwnPropertyDescriptor(proto, Symbol.iterator);
+        assert_equals(iteratorDesc.value, proto.entries, `@@iterator should equal entries`);
+        assert_equals(iteratorDesc.enumerable, false, `@@iterator enumerable`);
+        assert_equals(iteratorDesc.configurable, true, `@@iterator configurable`);
+        assert_equals(iteratorDesc.writable, true, `@@iterator writable`);
+
+        const sizeDesc = Object.getOwnPropertyDescriptor(proto, "size");
+        assert_equals(typeof sizeDesc.get, "function", `size getter should be a function`);
+        assert_equals(sizeDesc.set, undefined, `size should not have a setter`);
+        assert_equals(sizeDesc.enumerable, true, `size enumerable`);
+        assert_equals(sizeDesc.configurable, true, `size configurable`);
+        assert_equals(sizeDesc.get.length, 0, `size getter length`);
+        assert_equals(sizeDesc.get.name, "get size", `size getter name`);
+    }, `${this.name} interface: maplike<${member.idlType.map(t => t.idlType).join(", ")}>`);
+};
+
+IdlInterface.prototype.test_member_setlike = function(member) {
+    subsetTestByKey(this.name, test, () => {
+        const proto = this.get_interface_object().prototype;
+
+        const methods = [
+            ["entries", 0],
+            ["keys", 0],
+            ["values", 0],
+            ["forEach", 1],
+            ["has", 1]
+        ];
+        if (!member.readonly) {
+            methods.push(
+                ["add", 1],
+                ["delete", 1],
+                ["clear", 0]
+            );
+        }
+
+        for (const [name, length] of methods) {
+            const desc = Object.getOwnPropertyDescriptor(proto, name);
+            assert_equals(typeof desc.value, "function", `${name} should be a function`);
+            assert_equals(desc.enumerable, true, `${name} enumerable`);
+            assert_equals(desc.configurable, true, `${name} configurable`);
+            assert_equals(desc.writable, true, `${name} writable`);
+            assert_equals(desc.value.length, length, `${name} function object length should be ${length}`);
+            assert_equals(desc.value.name, name, `${name} function object should have the right name`);
+        }
+
+        const iteratorDesc = Object.getOwnPropertyDescriptor(proto, Symbol.iterator);
+        assert_equals(iteratorDesc.value, proto.values, `@@iterator should equal values`);
+        assert_equals(iteratorDesc.enumerable, false, `@@iterator enumerable`);
+        assert_equals(iteratorDesc.configurable, true, `@@iterator configurable`);
+        assert_equals(iteratorDesc.writable, true, `@@iterator writable`);
+
+        const sizeDesc = Object.getOwnPropertyDescriptor(proto, "size");
+        assert_equals(typeof sizeDesc.get, "function", `size getter should be a function`);
+        assert_equals(sizeDesc.set, undefined, `size should not have a setter`);
+        assert_equals(sizeDesc.enumerable, true, `size enumerable`);
+        assert_equals(sizeDesc.configurable, true, `size configurable`);
+        assert_equals(sizeDesc.get.length, 0, `size getter length`);
+        assert_equals(sizeDesc.get.name, "get size", `size getter name`);
+    }, `${this.name} interface: setlike<${member.idlType.map(t => t.idlType).join(", ")}>`);
+};
+
+IdlInterface.prototype.test_member_iterable = function(member) {
+    subsetTestByKey(this.name, test, () => {
+        const isPairIterator = member.idlType.length === 2;
+        const proto = this.get_interface_object().prototype;
+
+        const methods = [
+            ["entries", 0],
+            ["keys", 0],
+            ["values", 0],
+            ["forEach", 1]
+        ];
+
+        for (const [name, length] of methods) {
+            const desc = Object.getOwnPropertyDescriptor(proto, name);
+            assert_equals(typeof desc.value, "function", `${name} should be a function`);
+            assert_equals(desc.enumerable, true, `${name} enumerable`);
+            assert_equals(desc.configurable, true, `${name} configurable`);
+            assert_equals(desc.writable, true, `${name} writable`);
+            assert_equals(desc.value.length, length, `${name} function object length should be ${length}`);
+            assert_equals(desc.value.name, name, `${name} function object should have the right name`);
+
+            if (!isPairIterator) {
+                assert_equals(desc.value, Array.prototype[name], `${name} equality with Array.prototype version`);
+            }
+        }
+
+        const iteratorDesc = Object.getOwnPropertyDescriptor(proto, Symbol.iterator);
+        assert_equals(iteratorDesc.enumerable, false, `@@iterator enumerable`);
+        assert_equals(iteratorDesc.configurable, true, `@@iterator configurable`);
+        assert_equals(iteratorDesc.writable, true, `@@iterator writable`);
+
+        if (isPairIterator) {
+            assert_equals(iteratorDesc.value, proto.entries, `@@iterator equality with entries`);
+        } else {
+            assert_equals(iteratorDesc.value, Array.prototype[Symbol.iterator], `@@iterator equality with Array.prototype version`);
+        }
+    }, `${this.name} interface: iterable<${member.idlType.map(t => t.idlType).join(", ")}>`);
+};
+
+IdlInterface.prototype.test_member_async_iterable = function(member) {
+    subsetTestByKey(this.name, test, () => {
+        const isPairIterator = member.idlType.length === 2;
+        const proto = this.get_interface_object().prototype;
+
+        // Note that although the spec allows arguments, which will be passed to the @@asyncIterator
+        // method (which is either values or entries), those arguments must always be optional. So
+        // length of 0 is still correct for values and entries.
+        const methods = [
+            ["values", 0],
+        ];
+
+        if (isPairIterator) {
+            methods.push(
+                ["entries", 0],
+                ["keys", 0]
+            );
+        }
+
+        for (const [name, length] of methods) {
+            const desc = Object.getOwnPropertyDescriptor(proto, name);
+            assert_equals(typeof desc.value, "function", `${name} should be a function`);
+            assert_equals(desc.enumerable, true, `${name} enumerable`);
+            assert_equals(desc.configurable, true, `${name} configurable`);
+            assert_equals(desc.writable, true, `${name} writable`);
+            assert_equals(desc.value.length, length, `${name} function object length should be ${length}`);
+            assert_equals(desc.value.name, name, `${name} function object should have the right name`);
+        }
+
+        const iteratorDesc = Object.getOwnPropertyDescriptor(proto, Symbol.asyncIterator);
+        assert_equals(iteratorDesc.enumerable, false, `@@iterator enumerable`);
+        assert_equals(iteratorDesc.configurable, true, `@@iterator configurable`);
+        assert_equals(iteratorDesc.writable, true, `@@iterator writable`);
+
+        if (isPairIterator) {
+            assert_equals(iteratorDesc.value, proto.entries, `@@iterator equality with entries`);
+        } else {
+            assert_equals(iteratorDesc.value, proto.values, `@@iterator equality with values`);
+        }
+    }, `${this.name} interface: async iterable<${member.idlType.map(t => t.idlType).join(", ")}>`);
+};
+
+IdlInterface.prototype.test_member_stringifier = function(member)
+{
+    subsetTestByKey(this.name, test, function()
+    {
+        if (!this.should_have_interface_object()) {
+            return;
+        }
+
+        this.assert_interface_object_exists();
+
+        if (this.is_callback()) {
+            assert_false("prototype" in this.get_interface_object(),
+                         this.name + ' should not have a "prototype" property');
+            return;
+        }
+
+        assert_own_property(this.get_interface_object(), "prototype",
+                            'interface "' + this.name + '" does not have own property "prototype"');
+
+        // ". . . the property exists on the interface prototype object."
+        var interfacePrototypeObject = this.get_interface_object().prototype;
+        assert_own_property(interfacePrototypeObject, "toString",
+                "interface prototype object missing non-static operation");
+
+        var stringifierUnforgeable = member.isUnforgeable;
+        var desc = Object.getOwnPropertyDescriptor(interfacePrototypeObject, "toString");
+        // "The property has attributes { [[Writable]]: B,
+        // [[Enumerable]]: true, [[Configurable]]: B }, where B is false if the
+        // stringifier is unforgeable on the interface, and true otherwise."
+        assert_false("get" in desc, "property should not have a getter");
+        assert_false("set" in desc, "property should not have a setter");
+        assert_equals(desc.writable, !stringifierUnforgeable,
+                      "property should be writable if and only if not unforgeable");
+        assert_true(desc.enumerable, "property should be enumerable");
+        assert_equals(desc.configurable, !stringifierUnforgeable,
+                      "property should be configurable if and only if not unforgeable");
+        // "The value of the property is a Function object, which behaves as
+        // follows . . ."
+        assert_equals(typeof interfacePrototypeObject.toString, "function",
+                      "property must be a function");
+        // "The value of the Function object’s “length” property is the Number
+        // value 0."
+        assert_equals(interfacePrototypeObject.toString.length, 0,
+            "property has wrong .length");
+
+        // "Let O be the result of calling ToObject on the this value."
+        assert_throws_js(globalOf(interfacePrototypeObject.toString).TypeError, function() {
+            interfacePrototypeObject.toString.apply(null, []);
+        }, "calling stringifier with this = null didn't throw TypeError");
+
+        // "If O is not an object that implements the interface on which the
+        // stringifier was declared, then throw a TypeError."
+        //
+        // TODO: Test a platform object that implements some other
+        // interface.  (Have to be sure to get inheritance right.)
+        assert_throws_js(globalOf(interfacePrototypeObject.toString).TypeError, function() {
+            interfacePrototypeObject.toString.apply({}, []);
+        }, "calling stringifier with this = {} didn't throw TypeError");
+    }.bind(this), this.name + " interface: stringifier");
+};
+
+IdlInterface.prototype.test_members = function()
+{
+    var unexposed_members = new Set();
+    for (var i = 0; i < this.members.length; i++)
+    {
+        var member = this.members[i];
+        if (member.untested) {
+            continue;
+        }
+
+        if (!exposed_in(exposure_set(member, this.exposureSet))) {
+            if (!unexposed_members.has(member.name)) {
+                unexposed_members.add(member.name);
+                subsetTestByKey(this.name, test, function() {
+                    // It's not exposed, so we shouldn't find it anywhere.
+                    assert_false(member.name in this.get_interface_object(),
+                                "The interface object must not have a property " +
+                                format_value(member.name));
+                    assert_false(member.name in this.get_interface_object().prototype,
+                                "The prototype object must not have a property " +
+                                format_value(member.name));
+                }.bind(this), this.name + " interface: member " + member.name);
+            }
+            continue;
+        }
+
+        switch (member.type) {
+        case "const":
+            this.test_member_const(member);
+            break;
+
+        case "attribute":
+            // For unforgeable attributes, we do the checks in
+            // test_interface_of instead.
+            if (!member.isUnforgeable)
+            {
+                this.test_member_attribute(member);
+            }
+            if (member.special === "stringifier") {
+                this.test_member_stringifier(member);
+            }
+            break;
+
+        case "operation":
+            // TODO: Need to correctly handle multiple operations with the same
+            // identifier.
+            // For unforgeable operations, we do the checks in
+            // test_interface_of instead.
+            if (member.name) {
+                if (!member.isUnforgeable)
+                {
+                    this.test_member_operation(member);
+                }
+            } else if (member.special === "stringifier") {
+                this.test_member_stringifier(member);
+            }
+            break;
+
+        case "iterable":
+            if (member.async) {
+                this.test_member_async_iterable(member);
+            } else {
+                this.test_member_iterable(member);
+            }
+            break;
+        case "maplike":
+            this.test_member_maplike(member);
+            break;
+        case "setlike":
+            this.test_member_setlike(member);
+            break;
+        default:
+            // TODO: check more member types.
+            break;
+        }
+    }
+};
+
+IdlInterface.prototype.test_object = function(desc)
+{
+    var obj, exception = null;
+    try
+    {
+        obj = eval(desc);
+    }
+    catch(e)
+    {
+        exception = e;
+    }
+
+    var expected_typeof;
+    if (this.name == "HTMLAllCollection")
+    {
+        // Result of [[IsHTMLDDA]] slot
+        expected_typeof = "undefined";
+    }
+    else
+    {
+        expected_typeof = "object";
+    }
+
+    if (this.is_callback()) {
+        assert_equals(exception, null, "Unexpected exception when evaluating object");
+        assert_equals(typeof obj, expected_typeof, "wrong typeof object");
+    } else {
+        this.test_primary_interface_of(desc, obj, exception, expected_typeof);
+
+        var current_interface = this;
+        while (current_interface)
+        {
+            if (!(current_interface.name in this.array.members))
+            {
+                throw new IdlHarnessError("Interface " + current_interface.name + " not found (inherited by " + this.name + ")");
+            }
+            if (current_interface.prevent_multiple_testing && current_interface.already_tested)
+            {
+                return;
+            }
+            current_interface.test_interface_of(desc, obj, exception, expected_typeof);
+            current_interface = this.array.members[current_interface.base];
+        }
+    }
+};
+
+IdlInterface.prototype.test_primary_interface_of = function(desc, obj, exception, expected_typeof)
+{
+    // Only the object itself, not its members, are tested here, so if the
+    // interface is untested, there is nothing to do.
+    if (this.untested)
+    {
+        return;
+    }
+
+    // "The internal [[SetPrototypeOf]] method of every platform object that
+    // implements an interface with the [Global] extended
+    // attribute must execute the same algorithm as is defined for the
+    // [[SetPrototypeOf]] internal method of an immutable prototype exotic
+    // object."
+    // https://webidl.spec.whatwg.org/#platform-object-setprototypeof
+    if (this.is_global())
+    {
+        this.test_immutable_prototype("global platform object", obj);
+    }
+
+
+    // We can't easily test that its prototype is correct if there's no
+    // interface object, or the object is from a different global environment
+    // (not instanceof Object).  TODO: test in this case that its prototype at
+    // least looks correct, even if we can't test that it's actually correct.
+    if (this.should_have_interface_object()
+    && (typeof obj != expected_typeof || obj instanceof Object))
+    {
+        subsetTestByKey(this.name, test, function()
+        {
+            assert_equals(exception, null, "Unexpected exception when evaluating object");
+            assert_equals(typeof obj, expected_typeof, "wrong typeof object");
+            this.assert_interface_object_exists();
+            assert_own_property(this.get_interface_object(), "prototype",
+                                'interface "' + this.name + '" does not have own property "prototype"');
+
+            // "The value of the internal [[Prototype]] property of the
+            // platform object is the interface prototype object of the primary
+            // interface from the platform object’s associated global
+            // environment."
+            assert_equals(Object.getPrototypeOf(obj),
+                          this.get_interface_object().prototype,
+                          desc + "'s prototype is not " + this.name + ".prototype");
+        }.bind(this), this.name + " must be primary interface of " + desc);
+    }
+
+    // "The class string of a platform object that implements one or more
+    // interfaces must be the qualified name of the primary interface of the
+    // platform object."
+    subsetTestByKey(this.name, test, function()
+    {
+        assert_equals(exception, null, "Unexpected exception when evaluating object");
+        assert_equals(typeof obj, expected_typeof, "wrong typeof object");
+        assert_class_string(obj, this.get_qualified_name(), "class string of " + desc);
+        if (!this.has_stringifier())
+        {
+            assert_equals(String(obj), "[object " + this.get_qualified_name() + "]", "String(" + desc + ")");
+        }
+    }.bind(this), "Stringification of " + desc);
+};
+
+IdlInterface.prototype.test_interface_of = function(desc, obj, exception, expected_typeof)
+{
+    // TODO: Indexed and named properties, more checks on interface members
+    this.already_tested = true;
+    if (!shouldRunSubTest(this.name)) {
+        return;
+    }
+
+    var unexposed_properties = new Set();
+    for (var i = 0; i < this.members.length; i++)
+    {
+        var member = this.members[i];
+        if (member.untested) {
+            continue;
+        }
+        if (!exposed_in(exposure_set(member, this.exposureSet)))
+        {
+            if (!unexposed_properties.has(member.name))
+            {
+                unexposed_properties.add(member.name);
+                subsetTestByKey(this.name, test, function() {
+                    assert_equals(exception, null, "Unexpected exception when evaluating object");
+                    assert_false(member.name in obj);
+                }.bind(this), this.name + " interface: " + desc + ' must not have property "' + member.name + '"');
+            }
+            continue;
+        }
+        if (member.type == "attribute" && member.isUnforgeable)
+        {
+            var a_test = subsetTestByKey(this.name, async_test, this.name + " interface: " + desc + ' must have own property "' + member.name + '"');
+            a_test.step(function() {
+                assert_equals(exception, null, "Unexpected exception when evaluating object");
+                assert_equals(typeof obj, expected_typeof, "wrong typeof object");
+                // Call do_interface_attribute_asserts last, since it will call a_test.done()
+                this.do_interface_attribute_asserts(obj, member, a_test);
+            }.bind(this));
+        }
+        else if (member.type == "operation" &&
+                 member.name &&
+                 member.isUnforgeable)
+        {
+            var a_test = subsetTestByKey(this.name, async_test, this.name + " interface: " + desc + ' must have own property "' + member.name + '"');
+            a_test.step(function()
+            {
+                assert_equals(exception, null, "Unexpected exception when evaluating object");
+                assert_equals(typeof obj, expected_typeof, "wrong typeof object");
+                assert_own_property(obj, member.name,
+                                    "Doesn't have the unforgeable operation property");
+                this.do_member_operation_asserts(obj, member, a_test);
+            }.bind(this));
+        }
+        else if ((member.type == "const"
+        || member.type == "attribute"
+        || member.type == "operation")
+        && member.name)
+        {
+            subsetTestByKey(this.name, test, function()
+            {
+                assert_equals(exception, null, "Unexpected exception when evaluating object");
+                assert_equals(typeof obj, expected_typeof, "wrong typeof object");
+                if (member.special !== "static") {
+                    if (!this.is_global()) {
+                        assert_inherits(obj, member.name);
+                    } else {
+                        assert_own_property(obj, member.name);
+                    }
+
+                    if (member.type == "const")
+                    {
+                        assert_equals(obj[member.name], constValue(member.value));
+                    }
+                    if (member.type == "attribute")
+                    {
+                        // Attributes are accessor properties, so they might
+                        // legitimately throw an exception rather than returning
+                        // anything.
+                        var property, thrown = false;
+                        try
+                        {
+                            property = obj[member.name];
+                        }
+                        catch (e)
+                        {
+                            thrown = true;
+                        }
+                        if (!thrown)
+                        {
+                            if (this.name == "Document" && member.name == "all")
+                            {
+                                // Result of [[IsHTMLDDA]] slot
+                                assert_equals(typeof property, "undefined");
+                            }
+                            else
+                            {
+                                this.array.assert_type_is(property, member.idlType);
+                            }
+                        }
+                    }
+                    if (member.type == "operation")
+                    {
+                        assert_equals(typeof obj[member.name], "function");
+                    }
+                }
+            }.bind(this), this.name + " interface: " + desc + ' must inherit property "' + member + '" with the proper type');
+        }
+        // TODO: This is wrong if there are multiple operations with the same
+        // identifier.
+        // TODO: Test passing arguments of the wrong type.
+        if (member.type == "operation" && member.name && member.arguments.length)
+        {
+            var description =
+                this.name + " interface: calling " + member + " on " + desc +
+                " with too few arguments must throw TypeError";
+            var a_test = subsetTestByKey(this.name, async_test, description);
+            a_test.step(function()
+            {
+                assert_equals(exception, null, "Unexpected exception when evaluating object");
+                assert_equals(typeof obj, expected_typeof, "wrong typeof object");
+                var fn;
+                if (member.special !== "static") {
+                    if (!this.is_global() && !member.isUnforgeable) {
+                        assert_inherits(obj, member.name);
+                    } else {
+                        assert_own_property(obj, member.name);
+                    }
+                    fn = obj[member.name];
+                }
+                else
+                {
+                    assert_own_property(obj.constructor, member.name, "interface object must have static operation as own property");
+                    fn = obj.constructor[member.name];
+                }
+
+                var minLength = minOverloadLength(this.members.filter(function(m) {
+                    return m.type == "operation" && m.name == member.name;
+                }));
+                var args = [];
+                var cb = awaitNCallbacks(minLength, a_test.done.bind(a_test));
+                for (var i = 0; i < minLength; i++) {
+                    throwOrReject(a_test, member, fn, obj, args, "Called with " + i + " arguments", cb);
+
+                    args.push(create_suitable_object(member.arguments[i].idlType));
+                }
+                if (minLength === 0) {
+                    cb();
+                }
+            }.bind(this));
+        }
+
+        if (member.is_to_json_regular_operation()) {
+            this.test_to_json_operation(desc, obj, member);
+        }
+    }
+};
+
+IdlInterface.prototype.has_stringifier = function()
+{
+    if (this.name === "DOMException") {
+        // toString is inherited from Error, so don't assume we have the
+        // default stringifer
+        return true;
+    }
+    if (this.members.some(function(member) { return member.special === "stringifier"; })) {
+        return true;
+    }
+    if (this.base &&
+        this.array.members[this.base].has_stringifier()) {
+        return true;
+    }
+    return false;
+};
+
+IdlInterface.prototype.do_interface_attribute_asserts = function(obj, member, a_test)
+{
+    // This function tests WebIDL as of 2015-01-27.
+    // TODO: Consider [Exposed].
+
+    // This is called by test_member_attribute() with the prototype as obj if
+    // it is not a global, and the global otherwise, and by test_interface_of()
+    // with the object as obj.
+
+    var pendingPromises = [];
+
+    // "The name of the property is the identifier of the attribute."
+    assert_own_property(obj, member.name);
+
+    // "The property has attributes { [[Get]]: G, [[Set]]: S, [[Enumerable]]:
+    // true, [[Configurable]]: configurable }, where:
+    // "configurable is false if the attribute was declared with the
+    // [LegacyUnforgeable] extended attribute and true otherwise;
+    // "G is the attribute getter, defined below; and
+    // "S is the attribute setter, also defined below."
+    var desc = Object.getOwnPropertyDescriptor(obj, member.name);
+    assert_false("value" in desc, 'property descriptor should not have a "value" field');
+    assert_false("writable" in desc, 'property descriptor should not have a "writable" field');
+    assert_true(desc.enumerable, "property should be enumerable");
+    if (member.isUnforgeable)
+    {
+        assert_false(desc.configurable, "[LegacyUnforgeable] property must not be configurable");
+    }
+    else
+    {
+        assert_true(desc.configurable, "property must be configurable");
+    }
+
+
+    // "The attribute getter is a Function object whose behavior when invoked
+    // is as follows:"
+    assert_equals(typeof desc.get, "function", "getter must be Function");
+
+    // "If the attribute is a regular attribute, then:"
+    if (member.special !== "static") {
+        // "If O is not a platform object that implements I, then:
+        // "If the attribute was specified with the [LegacyLenientThis] extended
+        // attribute, then return undefined.
+        // "Otherwise, throw a TypeError."
+        if (!member.has_extended_attribute("LegacyLenientThis")) {
+            if (member.idlType.generic !== "Promise") {
+                assert_throws_js(globalOf(desc.get).TypeError, function() {
+                    desc.get.call({});
+                }.bind(this), "calling getter on wrong object type must throw TypeError");
+            } else {
+                pendingPromises.push(
+                    promise_rejects_js(a_test, TypeError, desc.get.call({}),
+                                    "calling getter on wrong object type must reject the return promise with TypeError"));
+            }
+        } else {
+            assert_equals(desc.get.call({}), undefined,
+                          "calling getter on wrong object type must return undefined");
+        }
+    }
+
+    // "The value of the Function object’s “length” property is the Number
+    // value 0."
+    assert_equals(desc.get.length, 0, "getter length must be 0");
+
+    // "Let name be the string "get " prepended to attribute’s identifier."
+    // "Perform ! SetFunctionName(F, name)."
+    assert_equals(desc.get.name, "get " + member.name,
+        "getter must have the name 'get " + member.name + "'");
+
+
+    // TODO: Test calling setter on the interface prototype (should throw
+    // TypeError in most cases).
+    if (member.readonly
+    && !member.has_extended_attribute("LegacyLenientSetter")
+    && !member.has_extended_attribute("PutForwards")
+    && !member.has_extended_attribute("Replaceable"))
+    {
+        // "The attribute setter is undefined if the attribute is declared
+        // readonly and has neither a [PutForwards] nor a [Replaceable]
+        // extended attribute declared on it."
+        assert_equals(desc.set, undefined, "setter must be undefined for readonly attributes");
+    }
+    else
+    {
+        // "Otherwise, it is a Function object whose behavior when
+        // invoked is as follows:"
+        assert_equals(typeof desc.set, "function", "setter must be function for PutForwards, Replaceable, or non-readonly attributes");
+
+        // "If the attribute is a regular attribute, then:"
+        if (member.special !== "static") {
+            // "If /validThis/ is false and the attribute was not specified
+            // with the [LegacyLenientThis] extended attribute, then throw a
+            // TypeError."
+            // "If the attribute is declared with a [Replaceable] extended
+            // attribute, then: ..."
+            // "If validThis is false, then return."
+            if (!member.has_extended_attribute("LegacyLenientThis")) {
+                assert_throws_js(globalOf(desc.set).TypeError, function() {
+                    desc.set.call({});
+                }.bind(this), "calling setter on wrong object type must throw TypeError");
+            } else {
+                assert_equals(desc.set.call({}), undefined,
+                              "calling setter on wrong object type must return undefined");
+            }
+        }
+
+        // "The value of the Function object’s “length” property is the Number
+        // value 1."
+        assert_equals(desc.set.length, 1, "setter length must be 1");
+
+        // "Let name be the string "set " prepended to id."
+        // "Perform ! SetFunctionName(F, name)."
+        assert_equals(desc.set.name, "set " + member.name,
+            "The attribute setter must have the name 'set " + member.name + "'");
+    }
+
+    Promise.all(pendingPromises).then(a_test.done.bind(a_test));
+}
+
+/// IdlInterfaceMember ///
+function IdlInterfaceMember(obj)
+{
+    /**
+     * obj is an object produced by the WebIDLParser.js "ifMember" production.
+     * We just forward all properties to this object without modification,
+     * except for special extAttrs handling.
+     */
+    for (var k in obj.toJSON())
+    {
+        this[k] = obj[k];
+    }
+    if (!("extAttrs" in this))
+    {
+        this.extAttrs = [];
+    }
+
+    this.isUnforgeable = this.has_extended_attribute("LegacyUnforgeable");
+    this.isUnscopable = this.has_extended_attribute("Unscopable");
+}
+
+IdlInterfaceMember.prototype = Object.create(IdlObject.prototype);
+
+IdlInterfaceMember.prototype.toJSON = function() {
+    return this;
+};
+
+IdlInterfaceMember.prototype.is_to_json_regular_operation = function() {
+    return this.type == "operation" && this.special !== "static" && this.name == "toJSON";
+};
+
+IdlInterfaceMember.prototype.toString = function() {
+    function formatType(type) {
+        var result;
+        if (type.generic) {
+            result = type.generic + "<" + type.idlType.map(formatType).join(", ") + ">";
+        } else if (type.union) {
+            result = "(" + type.subtype.map(formatType).join(" or ") + ")";
+        } else {
+            result = type.idlType;
+        }
+        if (type.nullable) {
+            result += "?"
+        }
+        return result;
+    }
+
+    if (this.type === "operation") {
+        var args = this.arguments.map(function(m) {
+            return [
+                m.optional ? "optional " : "",
+                formatType(m.idlType),
+                m.variadic ? "..." : "",
+            ].join("");
+        }).join(", ");
+        return this.name + "(" + args + ")";
+    }
+
+    return this.name;
+}
+
+/// Internal helper functions ///
+function create_suitable_object(type)
+{
+    /**
+     * type is an object produced by the WebIDLParser.js "type" production.  We
+     * return a JavaScript value that matches the type, if we can figure out
+     * how.
+     */
+    if (type.nullable)
+    {
+        return null;
+    }
+    switch (type.idlType)
+    {
+        case "any":
+        case "boolean":
+            return true;
+
+        case "byte": case "octet": case "short": case "unsigned short":
+        case "long": case "unsigned long": case "long long":
+        case "unsigned long long": case "float": case "double":
+        case "unrestricted float": case "unrestricted double":
+            return 7;
+
+        case "DOMString":
+        case "ByteString":
+        case "USVString":
+            return "foo";
+
+        case "object":
+            return {a: "b"};
+
+        case "Node":
+            return document.createTextNode("abc");
+    }
+    return null;
+}
+
+/// IdlEnum ///
+// Used for IdlArray.prototype.assert_type_is
+function IdlEnum(obj)
+{
+    /**
+     * obj is an object produced by the WebIDLParser.js "dictionary"
+     * production.
+     */
+
+    /** Self-explanatory. */
+    this.name = obj.name;
+
+    /** An array of values produced by the "enum" production. */
+    this.values = obj.values;
+
+}
+
+IdlEnum.prototype = Object.create(IdlObject.prototype);
+
+/// IdlCallback ///
+// Used for IdlArray.prototype.assert_type_is
+function IdlCallback(obj)
+{
+    /**
+     * obj is an object produced by the WebIDLParser.js "callback"
+     * production.
+     */
+
+    /** Self-explanatory. */
+    this.name = obj.name;
+
+    /** Arguments for the callback. */
+    this.arguments = obj.arguments;
+}
+
+IdlCallback.prototype = Object.create(IdlObject.prototype);
+
+/// IdlTypedef ///
+// Used for IdlArray.prototype.assert_type_is
+function IdlTypedef(obj)
+{
+    /**
+     * obj is an object produced by the WebIDLParser.js "typedef"
+     * production.
+     */
+
+    /** Self-explanatory. */
+    this.name = obj.name;
+
+    /** The idlType that we are supposed to be typedeffing to. */
+    this.idlType = obj.idlType;
+
+}
+
+IdlTypedef.prototype = Object.create(IdlObject.prototype);
+
+/// IdlNamespace ///
+function IdlNamespace(obj)
+{
+    this.name = obj.name;
+    this.extAttrs = obj.extAttrs;
+    this.untested = obj.untested;
+    /** A back-reference to our IdlArray. */
+    this.array = obj.array;
+
+    /** An array of IdlInterfaceMembers. */
+    this.members = obj.members.map(m => new IdlInterfaceMember(m));
+}
+
+IdlNamespace.prototype = Object.create(IdlObject.prototype);
+
+IdlNamespace.prototype.do_member_operation_asserts = function (memberHolderObject, member, a_test)
+{
+    var desc = Object.getOwnPropertyDescriptor(memberHolderObject, member.name);
+
+    assert_false("get" in desc, "property should not have a getter");
+    assert_false("set" in desc, "property should not have a setter");
+    assert_equals(
+        desc.writable,
+        !member.isUnforgeable,
+        "property should be writable if and only if not unforgeable");
+    assert_true(desc.enumerable, "property should be enumerable");
+    assert_equals(
+        desc.configurable,
+        !member.isUnforgeable,
+        "property should be configurable if and only if not unforgeable");
+
+    assert_equals(
+        typeof memberHolderObject[member.name],
+        "function",
+         "property must be a function");
+
+    assert_equals(
+        memberHolderObject[member.name].length,
+        minOverloadLength(this.members.filter(function(m) {
+            return m.type == "operation" && m.name == member.name;
+        })),
+        "operation has wrong .length");
+    a_test.done();
+}
+
+IdlNamespace.prototype.test_member_operation = function(member)
+{
+    if (!shouldRunSubTest(this.name)) {
+        return;
+    }
+    var a_test = subsetTestByKey(
+        this.name,
+        async_test,
+        this.name + ' namespace: operation ' + member);
+    a_test.step(function() {
+        assert_own_property(
+            self[this.name],
+            member.name,
+            'namespace object missing operation ' + format_value(member.name));
+
+        this.do_member_operation_asserts(self[this.name], member, a_test);
+    }.bind(this));
+};
+
+IdlNamespace.prototype.test_member_attribute = function (member)
+{
+    if (!shouldRunSubTest(this.name)) {
+        return;
+    }
+    var a_test = subsetTestByKey(
+        this.name,
+        async_test,
+        this.name + ' namespace: attribute ' + member.name);
+    a_test.step(function()
+    {
+        assert_own_property(
+            self[this.name],
+            member.name,
+            this.name + ' does not have property ' + format_value(member.name));
+
+        var desc = Object.getOwnPropertyDescriptor(self[this.name], member.name);
+        assert_equals(desc.set, undefined, "setter must be undefined for namespace members");
+        a_test.done();
+    }.bind(this));
+};
+
+IdlNamespace.prototype.test_self = function ()
+{
+    /**
+     * TODO(lukebjerring): Assert:
+     * - "Note that unlike interfaces or dictionaries, namespaces do not create types."
+     */
+
+    subsetTestByKey(this.name, test, () => {
+        assert_true(this.extAttrs.every(o => o.name === "Exposed" || o.name === "SecureContext"),
+            "Only the [Exposed] and [SecureContext] extended attributes are applicable to namespaces");
+        assert_true(this.has_extended_attribute("Exposed"),
+            "Namespaces must be annotated with the [Exposed] extended attribute");
+    }, `${this.name} namespace: extended attributes`);
+
+    const namespaceObject = self[this.name];
+
+    subsetTestByKey(this.name, test, () => {
+        const desc = Object.getOwnPropertyDescriptor(self, this.name);
+        assert_equals(desc.value, namespaceObject, `wrong value for ${this.name} namespace object`);
+        assert_true(desc.writable, "namespace object should be writable");
+        assert_false(desc.enumerable, "namespace object should not be enumerable");
+        assert_true(desc.configurable, "namespace object should be configurable");
+        assert_false("get" in desc, "namespace object should not have a getter");
+        assert_false("set" in desc, "namespace object should not have a setter");
+    }, `${this.name} namespace: property descriptor`);
+
+    subsetTestByKey(this.name, test, () => {
+        assert_true(Object.isExtensible(namespaceObject));
+    }, `${this.name} namespace: [[Extensible]] is true`);
+
+    subsetTestByKey(this.name, test, () => {
+        assert_true(namespaceObject instanceof Object);
+
+        if (this.name === "console") {
+            // https://console.spec.whatwg.org/#console-namespace
+            const namespacePrototype = Object.getPrototypeOf(namespaceObject);
+            assert_equals(Reflect.ownKeys(namespacePrototype).length, 0);
+            assert_equals(Object.getPrototypeOf(namespacePrototype), Object.prototype);
+        } else {
+            assert_equals(Object.getPrototypeOf(namespaceObject), Object.prototype);
+        }
+    }, `${this.name} namespace: [[Prototype]] is Object.prototype`);
+
+    subsetTestByKey(this.name, test, () => {
+        assert_equals(typeof namespaceObject, "object");
+    }, `${this.name} namespace: typeof is "object"`);
+
+    subsetTestByKey(this.name, test, () => {
+        assert_equals(
+            Object.getOwnPropertyDescriptor(namespaceObject, "length"),
+            undefined,
+            "length property must be undefined"
+        );
+    }, `${this.name} namespace: has no length property`);
+
+    subsetTestByKey(this.name, test, () => {
+        assert_equals(
+            Object.getOwnPropertyDescriptor(namespaceObject, "name"),
+            undefined,
+            "name property must be undefined"
+        );
+    }, `${this.name} namespace: has no name property`);
+};
+
+IdlNamespace.prototype.test = function ()
+{
+    if (!this.untested) {
+        this.test_self();
+    }
+
+    for (const v of Object.values(this.members)) {
+        switch (v.type) {
+
+        case 'operation':
+            this.test_member_operation(v);
+            break;
+
+        case 'attribute':
+            this.test_member_attribute(v);
+            break;
+
+        default:
+            throw 'Invalid namespace member ' + v.name + ': ' + v.type + ' not supported';
+        }
+    };
+};
+
+}());
+
+/**
+ * idl_test is a promise_test wrapper that handles the fetching of the IDL,
+ * avoiding repetitive boilerplate.
+ *
+ * @param {String[]} srcs Spec name(s) for source idl files (fetched from
+ *      /interfaces/{name}.idl).
+ * @param {String[]} deps Spec name(s) for dependency idl files (fetched
+ *      from /interfaces/{name}.idl). Order is important - dependencies from
+ *      each source will only be included if they're already know to be a
+ *      dependency (i.e. have already been seen).
+ * @param {Function} setup_func Function for extra setup of the idl_array, such
+ *      as adding objects. Do not call idl_array.test() in the setup; it is
+ *      called by this function (idl_test).
+ */
+function idl_test(srcs, deps, idl_setup_func) {
+    return promise_test(function (t) {
+        var idl_array = new IdlArray();
+        var setup_error = null;
+        const validationIgnored = [
+            "constructor-member",
+            "dict-arg-default",
+            "require-exposed"
+        ];
+        return Promise.all(
+            srcs.concat(deps).map(fetch_spec))
+            .then(function(results) {
+                const astArray = results.map(result =>
+                    WebIDL2.parse(result.idl, { sourceName: result.spec })
+                );
+                test(() => {
+                    const validations = WebIDL2.validate(astArray)
+                        .filter(v => !validationIgnored.includes(v.ruleName));
+                    if (validations.length) {
+                        const message = validations.map(v => v.message).join("\n\n");
+                        throw new Error(message);
+                    }
+                }, "idl_test validation");
+                for (var i = 0; i < srcs.length; i++) {
+                    idl_array.internal_add_idls(astArray[i]);
+                }
+                for (var i = srcs.length; i < srcs.length + deps.length; i++) {
+                    idl_array.internal_add_dependency_idls(astArray[i]);
+                }
+            })
+            .then(function() {
+                if (idl_setup_func) {
+                    return idl_setup_func(idl_array, t);
+                }
+            })
+            .catch(function(e) { setup_error = e || 'IDL setup failed.'; })
+            .then(function () {
+                var error = setup_error;
+                try {
+                    idl_array.test(); // Test what we can.
+                } catch (e) {
+                    // If testing fails hard here, the original setup error
+                    // is more likely to be the real cause.
+                    error = error || e;
+                }
+                if (error) {
+                    throw error;
+                }
+            });
+    }, 'idl_test setup');
+}
+
+/**
+ * fetch_spec is a shorthand for a Promise that fetches the spec's content.
+ */
+function fetch_spec(spec) {
+    var url = '/interfaces/' + spec + '.idl';
+    return fetch(url).then(function (r) {
+        if (!r.ok) {
+            throw new IdlHarnessError("Error fetching " + url + ".");
+        }
+        return r.text();
+    }).then(idl => ({ spec, idl }));
+}
+// vim: set expandtab shiftwidth=4 tabstop=4 foldmarker=@{,@} foldmethod=marker:
diff --git a/test/wpt/tests/resources/idlharness.js.headers b/test/wpt/tests/resources/idlharness.js.headers
new file mode 100644
index 0000000..5e8f640
--- /dev/null
+++ b/test/wpt/tests/resources/idlharness.js.headers
@@ -0,0 +1,2 @@
+Content-Type: text/javascript; charset=utf-8
+Cache-Control: max-age=3600
diff --git a/test/wpt/tests/resources/readme.md b/test/wpt/tests/resources/readme.md
new file mode 100644
index 0000000..09a62fb
--- /dev/null
+++ b/test/wpt/tests/resources/readme.md
@@ -0,0 +1,14 @@
+# Resources
+
+This directory contains utilities intended for use by tests and maintained as project infrastructure.
+It does not contain tests.
+
+## `testharness.js`
+
+`testharness.js` is a framework for writing low-level tests of
+browser functionality in javascript. It provides a convenient API for
+making assertions and is intended to work for both simple synchronous
+tests, and tests of asynchronous behaviour.
+
+Complete documentation is available in the `docs/` directory of this repository
+and on the web at https://web-platform-tests.org/writing-tests/.
diff --git a/test/wpt/tests/resources/sriharness.js b/test/wpt/tests/resources/sriharness.js
new file mode 100644
index 0000000..943d677
--- /dev/null
+++ b/test/wpt/tests/resources/sriharness.js
@@ -0,0 +1,226 @@
+// `integrityValue` indicates the 'integrity' attribute value at the time of
+// #prepare-a-script.
+//
+// `integrityValueAfterPrepare` indicates how the 'integrity' attribute value
+// is modified after #prepare-a-script:
+// - `undefined` => not modified.
+// - `null` => 'integrity' attribute is removed.
+// - others => 'integrity' attribute value is set to that value.
+//
+// TODO: Make the arguments a dictionary for readability in the test files.
+var SRIScriptTest = function(pass, name, src, integrityValue, crossoriginValue, nonce, integrityValueAfterPrepare) {
+    this.pass = pass;
+    this.name = "Script: " + name;
+    this.src = src;
+    this.integrityValue = integrityValue;
+    this.crossoriginValue = crossoriginValue;
+    this.nonce = nonce;
+    this.integrityValueAfterPrepare = integrityValueAfterPrepare;
+}
+
+SRIScriptTest.prototype.execute = function() {
+    var test = async_test(this.name);
+    var e = document.createElement("script");
+    e.src = this.src;
+    if (this.integrityValue) {
+      e.setAttribute("integrity", this.integrityValue);
+    }
+    if(this.crossoriginValue) {
+        e.setAttribute("crossorigin", this.crossoriginValue);
+    }
+    if(this.nonce) {
+      e.setAttribute("nonce", this.nonce);
+    }
+    if(this.pass) {
+        e.addEventListener("load", function() {test.done()});
+        e.addEventListener("error", function() {
+            test.step(function(){ assert_unreached("Good load fired error handler.") })
+        });
+    } else {
+       e.addEventListener("load", function() {
+            test.step(function() { assert_unreached("Bad load succeeded.") })
+        });
+       e.addEventListener("error", function() {test.done()});
+    }
+    document.body.appendChild(e);
+
+    if (this.integrityValueAfterPrepare === null) {
+      e.removeAttribute("integrity");
+    } else if (this.integrityValueAfterPrepare !== undefined) {
+      e.setAttribute("integrity", this.integrityValueAfterPrepare);
+    }
+};
+
+function set_extra_attributes(element, attrs) {
+  // Apply the rest of the attributes, if any.
+  for (const [attr_name, attr_val] of Object.entries(attrs)) {
+    element[attr_name] = attr_val;
+  }
+}
+
+function buildElementFromDestination(resource_url, destination, attrs) {
+  // Assert: |destination| is a valid destination.
+  let element;
+
+  // The below switch is responsible for:
+  //   1. Creating the correct subresource element
+  //   2. Setting said element's href, src, or fetch-instigating property
+  //      appropriately.
+  switch (destination) {
+    case "script":
+      element = document.createElement(destination);
+      set_extra_attributes(element, attrs);
+      element.src = resource_url;
+      break;
+    case "style":
+      element = document.createElement('link');
+      set_extra_attributes(element, attrs);
+      element.rel = 'stylesheet';
+      element.href = resource_url;
+      break;
+    case "image":
+      element = document.createElement('img');
+      set_extra_attributes(element, attrs);
+      element.src = resource_url;
+      break;
+    default:
+      assert_unreached("INVALID DESTINATION");
+  }
+
+  return element;
+}
+
+// When using SRIPreloadTest, also include /preload/resources/preload_helper.js
+// |number_of_requests| is used to ensure that preload requests are actually
+// reused as expected.
+const SRIPreloadTest = (preload_sri_success, subresource_sri_success, name,
+                        number_of_requests, destination, resource_url,
+                        link_attrs, subresource_attrs) => {
+  const test = async_test(name);
+  const link = document.createElement('link');
+
+  // Early-fail in UAs that do not support `preload` links.
+  test.step_func(() => {
+    assert_true(link.relList.supports('preload'),
+      "This test is automatically failing because the browser does not" +
+      "support `preload` links.");
+  })();
+
+  // Build up the link.
+  link.rel = 'preload';
+  link.as = destination;
+  link.href = resource_url;
+  for (const [attr_name, attr_val] of Object.entries(link_attrs)) {
+    link[attr_name] = attr_val; // This may override `rel` to modulepreload.
+  }
+
+  // Preload + subresource success and failure loading functions.
+  const valid_preload_failed = test.step_func(() =>
+    { assert_unreached("Valid preload fired error handler.") });
+  const invalid_preload_succeeded = test.step_func(() =>
+    { assert_unreached("Invalid preload load succeeded.") });
+  const valid_subresource_failed = test.step_func(() =>
+    { assert_unreached("Valid subresource fired error handler.") });
+  const invalid_subresource_succeeded = test.step_func(() =>
+    { assert_unreached("Invalid subresource load succeeded.") });
+  const subresource_pass = test.step_func(() => {
+    verifyNumberOfResourceTimingEntries(resource_url, number_of_requests);
+    test.done();
+  });
+  const preload_pass = test.step_func(() => {
+    const subresource_element = buildElementFromDestination(
+      resource_url,
+      destination,
+      subresource_attrs
+    );
+
+    if (subresource_sri_success) {
+      subresource_element.onload = subresource_pass;
+      subresource_element.onerror = valid_subresource_failed;
+    } else {
+      subresource_element.onload = invalid_subresource_succeeded;
+      subresource_element.onerror = subresource_pass;
+    }
+
+    document.body.append(subresource_element);
+  });
+
+  if (preload_sri_success) {
+    link.onload = preload_pass;
+    link.onerror = valid_preload_failed;
+  } else {
+    link.onload = invalid_preload_succeeded;
+    link.onerror = preload_pass;
+  }
+
+  document.head.append(link);
+}
+
+// <link> tests
+// Style tests must be done synchronously because they rely on the presence
+// and absence of global style, which can affect later tests. Thus, instead
+// of executing them one at a time, the style tests are implemented as a
+// queue that builds up a list of tests, and then executes them one at a
+// time.
+var SRIStyleTest = function(queue, pass, name, attrs, customCallback, altPassValue) {
+    this.pass = pass;
+    this.name = "Style: " + name;
+    this.customCallback = customCallback || function () {};
+    this.attrs = attrs || {};
+    this.passValue = altPassValue || "rgb(255, 255, 0)";
+
+    this.test = async_test(this.name);
+
+    this.queue = queue;
+    this.queue.push(this);
+}
+
+SRIStyleTest.prototype.execute = function() {
+  var that = this;
+    var container = document.getElementById("container");
+    while (container.hasChildNodes()) {
+      container.removeChild(container.firstChild);
+    }
+
+    var test = this.test;
+
+    var div = document.createElement("div");
+    div.className = "testdiv";
+    var e = document.createElement("link");
+
+    // The link relation is guaranteed to not be "preload" or "modulepreload".
+    this.attrs.rel = this.attrs.rel || "stylesheet";
+    for (var key in this.attrs) {
+        if (this.attrs.hasOwnProperty(key)) {
+            e.setAttribute(key, this.attrs[key]);
+        }
+    }
+
+    if(this.pass) {
+        e.addEventListener("load", function() {
+            test.step(function() {
+                var background = window.getComputedStyle(div, null).getPropertyValue("background-color");
+                assert_equals(background, that.passValue);
+                test.done();
+            });
+        });
+        e.addEventListener("error", function() {
+            test.step(function(){ assert_unreached("Good load fired error handler.") })
+        });
+    } else {
+        e.addEventListener("load", function() {
+             test.step(function() { assert_unreached("Bad load succeeded.") })
+         });
+        e.addEventListener("error", function() {
+            test.step(function() {
+                var background = window.getComputedStyle(div, null).getPropertyValue("background-color");
+                assert_not_equals(background, that.passValue);
+                test.done();
+            });
+        });
+    }
+    container.appendChild(div);
+    container.appendChild(e);
+    this.customCallback(e, container);
+};
+
diff --git a/test/wpt/tests/resources/test-only-api.js b/test/wpt/tests/resources/test-only-api.js
new file mode 100644
index 0000000..a66eb44
--- /dev/null
+++ b/test/wpt/tests/resources/test-only-api.js
@@ -0,0 +1,31 @@
+'use strict';
+
+/* Whether the browser is Chromium-based with MojoJS enabled */
+const isChromiumBased = 'MojoInterfaceInterceptor' in self;
+/* Whether the browser is WebKit-based with internal test-only API enabled */
+const isWebKitBased = !isChromiumBased && 'internals' in self;
+
+/**
+ * Loads a script in a window or worker.
+ *
+ * @param {string} path - A script path
+ * @returns {Promise}
+ */
+function loadScript(path) {
+  if (typeof document === 'undefined') {
+    // Workers (importScripts is synchronous and may throw.)
+    importScripts(path);
+    return Promise.resolve();
+  } else {
+    // Window
+    const script = document.createElement('script');
+    script.src = path;
+    script.async = false;
+    const p = new Promise((resolve, reject) => {
+      script.onload = () => { resolve(); };
+      script.onerror = e => { reject(`Error loading ${path}`); };
+    })
+    document.head.appendChild(script);
+    return p;
+  }
+}
diff --git a/test/wpt/tests/resources/test-only-api.js.headers b/test/wpt/tests/resources/test-only-api.js.headers
new file mode 100644
index 0000000..5e8f640
--- /dev/null
+++ b/test/wpt/tests/resources/test-only-api.js.headers
@@ -0,0 +1,2 @@
+Content-Type: text/javascript; charset=utf-8
+Cache-Control: max-age=3600
diff --git a/test/wpt/tests/resources/test-only-api.m.js b/test/wpt/tests/resources/test-only-api.m.js
new file mode 100644
index 0000000..984f635
--- /dev/null
+++ b/test/wpt/tests/resources/test-only-api.m.js
@@ -0,0 +1,5 @@
+/* Whether the browser is Chromium-based with MojoJS enabled */
+export const isChromiumBased = 'MojoInterfaceInterceptor' in self;
+
+/* Whether the browser is WebKit-based with internal test-only API enabled */
+export const isWebKitBased = !isChromiumBased && 'internals' in self;
diff --git a/test/wpt/tests/resources/test-only-api.m.js.headers b/test/wpt/tests/resources/test-only-api.m.js.headers
new file mode 100644
index 0000000..5e8f640
--- /dev/null
+++ b/test/wpt/tests/resources/test-only-api.m.js.headers
@@ -0,0 +1,2 @@
+Content-Type: text/javascript; charset=utf-8
+Cache-Control: max-age=3600
diff --git a/test/wpt/tests/resources/test/README.md b/test/wpt/tests/resources/test/README.md
new file mode 100644
index 0000000..edc03ef
--- /dev/null
+++ b/test/wpt/tests/resources/test/README.md
@@ -0,0 +1,83 @@
+# `testharness.js` test suite
+
+The test suite for the `testharness.js` testing framework.
+
+## Executing Tests
+
+Install the following dependencies:
+
+- [Python 2.7.9+](https://www.python.org/)
+- [the tox Python package](https://tox.readthedocs.io/en/latest/)
+- [the Mozilla Firefox web browser](https://mozilla.org/firefox)
+- [the GeckoDriver server](https://github.com/mozilla/geckodriver)
+
+Make sure `geckodriver` can be found in your `PATH`.
+
+Currently, the tests should be run with the latest *Firefox Nightly*. In order to
+specify the path to Firefox Nightly, use the following command-line option:
+
+    tox -- --binary=/path/to/FirefoxNightly
+
+### Automated Script
+
+Alternatively, you may run `tools/ci/ci_resources_unittest.sh`, which only depends on
+Python 2. The script will install other dependencies automatically and start `tox` with
+the correct arguments.
+
+## Authoring Tests
+
+Test cases are expressed as `.html` files located within the `tests/unit/` and
+`tests/functional/` sub-directories. Each test should include the
+`testharness.js` library with the following markup:
+
+    <script src="/resources/testharness.js"></script>
+    <script src="/resources/testharnessreport.js"></script>
+
+This should be followed by one or more `<script>` tags that interface with the
+`testharness.js` API in some way. For example:
+
+    <script>
+    test(function() {
+        1 = 1;
+      }, 'This test is expected to fail.');
+    </script>
+
+### Unit tests
+
+The "unit test" type allows for concisely testing the expected behavior of
+assertion methods. These tests may define any number of sub-tests; the
+acceptance criteria is simply that all tests executed pass.
+
+### Functional tests
+
+Thoroughly testing the behavior of the harness itself requires ensuring a
+number of considerations which cannot be verified with the "unit testing"
+strategy. These include:
+
+- Ensuring that some tests are not run
+- Ensuring conditions that cause test failures
+- Ensuring conditions that cause harness errors
+
+Functional tests allow for these details to be verified. Every functional test
+must include a summary of the expected results as a JSON string within a
+`<script>` tag with an `id` of `"expected"`, e.g.:
+
+    <script type="text/json" id="expected">
+    {
+      "summarized_status": {
+        "message": null,
+        "stack": null,
+        "status_string": "OK"
+      },
+      "summarized_tests": [
+        {
+          "message": "ReferenceError: invalid assignment left-hand side",
+          "name": "Sample HTML5 API Tests",
+          "properties": {},
+          "stack": "(implementation-defined)",
+          "status_string": "FAIL"
+        }
+      ],
+      "type": "complete"
+    }
+    </script>
diff --git a/test/wpt/tests/resources/test/conftest.py b/test/wpt/tests/resources/test/conftest.py
new file mode 100644
index 0000000..7253cac
--- /dev/null
+++ b/test/wpt/tests/resources/test/conftest.py
@@ -0,0 +1,269 @@
+import copy
+import json
+import os
+import ssl
+import sys
+import subprocess
+import urllib
+
+import html5lib
+import py
+import pytest
+
+from wptserver import WPTServer
+
+HERE = os.path.dirname(os.path.abspath(__file__))
+WPT_ROOT = os.path.normpath(os.path.join(HERE, '..', '..'))
+HARNESS = os.path.join(HERE, 'harness.html')
+TEST_TYPES = ('functional', 'unit')
+
+sys.path.insert(0, os.path.normpath(os.path.join(WPT_ROOT, "tools")))
+import localpaths
+
+sys.path.insert(0, os.path.normpath(os.path.join(WPT_ROOT, "tools", "webdriver")))
+import webdriver
+
+
+def pytest_addoption(parser):
+    parser.addoption("--binary", action="store", default=None, help="path to browser binary")
+    parser.addoption("--headless", action="store_true", default=False, help="run browser in headless mode")
+
+
+def pytest_collect_file(file_path, path, parent):
+    if file_path.suffix.lower() != '.html':
+        return
+
+    # Tests are organized in directories by type
+    test_type = os.path.relpath(str(file_path), HERE)
+    if os.path.sep not in test_type or ".." in test_type:
+        # HTML files in this directory are not tests
+        return
+    test_type = test_type.split(os.path.sep)[1]
+
+    # Handle the deprecation of Node construction in pytest6
+    # https://docs.pytest.org/en/stable/deprecations.html#node-construction-changed-to-node-from-parent
+    if hasattr(HTMLItem, "from_parent"):
+        return HTMLItem.from_parent(parent, filename=str(file_path), test_type=test_type)
+    return HTMLItem(parent, str(file_path), test_type)
+
+
+def pytest_configure(config):
+    config.proc = subprocess.Popen(["geckodriver"])
+    config.add_cleanup(config.proc.kill)
+
+    capabilities = {"alwaysMatch": {"acceptInsecureCerts": True, "moz:firefoxOptions": {}}}
+    if config.getoption("--binary"):
+        capabilities["alwaysMatch"]["moz:firefoxOptions"]["binary"] = config.getoption("--binary")
+    if config.getoption("--headless"):
+        capabilities["alwaysMatch"]["moz:firefoxOptions"]["args"] = ["--headless"]
+
+    config.driver = webdriver.Session("localhost", 4444,
+                                      capabilities=capabilities)
+    config.add_cleanup(config.driver.end)
+
+    # Although the name of the `_create_unverified_context` method suggests
+    # that it is not intended for external consumption, the standard library's
+    # documentation explicitly endorses its use:
+    #
+    # > To revert to the previous, unverified, behavior
+    # > ssl._create_unverified_context() can be passed to the context
+    # > parameter.
+    #
+    # https://docs.python.org/2/library/httplib.html#httplib.HTTPSConnection
+    config.ssl_context = ssl._create_unverified_context()
+
+    config.server = WPTServer(WPT_ROOT)
+    config.server.start(config.ssl_context)
+    config.add_cleanup(config.server.stop)
+
+
+def resolve_uri(context, uri):
+    if uri.startswith('/'):
+        base = WPT_ROOT
+        path = uri[1:]
+    else:
+        base = os.path.dirname(context)
+        path = uri
+
+    return os.path.exists(os.path.join(base, path))
+
+
+def _summarize(actual):
+    def _scrub_stack(test_obj):
+        copy = dict(test_obj)
+        del copy['stack']
+        return copy
+
+    def _expand_status(status_obj):
+        for key, value in [item for item in status_obj.items()]:
+            # In "status" and "test" objects, the "status" value enum
+            # definitions are interspersed with properties for unrelated
+            # metadata. The following condition is a best-effort attempt to
+            # ignore non-enum properties.
+            if key != key.upper() or not isinstance(value, int):
+                continue
+
+            del status_obj[key]
+
+            if status_obj['status'] == value:
+                status_obj[u'status_string'] = key
+
+        del status_obj['status']
+
+        return status_obj
+
+    def _summarize_test(test_obj):
+        del test_obj['index']
+
+        assert 'phase' in test_obj
+        assert 'phases' in test_obj
+        assert 'COMPLETE' in test_obj['phases']
+        assert test_obj['phase'] == test_obj['phases']['COMPLETE']
+        del test_obj['phases']
+        del test_obj['phase']
+
+        return _expand_status(_scrub_stack(test_obj))
+
+    def _summarize_status(status_obj):
+        return _expand_status(_scrub_stack(status_obj))
+
+
+    summarized = {}
+
+    summarized[u'summarized_status'] = _summarize_status(actual['status'])
+    summarized[u'summarized_tests'] = [
+        _summarize_test(test) for test in actual['tests']]
+    summarized[u'summarized_tests'].sort(key=lambda test_obj: test_obj.get('name'))
+    summarized[u'summarized_asserts'] = [
+        {"assert_name": assert_item["assert_name"],
+        "test": assert_item["test"]["name"] if assert_item["test"] else None,
+        "args": assert_item["args"],
+        "status": assert_item["status"]} for assert_item in actual["asserts"]]
+    summarized[u'type'] = actual['type']
+
+    return summarized
+
+
+class HTMLItem(pytest.Item, pytest.Collector):
+    def __init__(self, parent, filename, test_type):
+        self.url = parent.session.config.server.url(filename)
+        self.type = test_type
+        # Some tests are reliant on the WPT servers substitution functionality,
+        # so tests must be retrieved from the server rather than read from the
+        # file system directly.
+        handle = urllib.request.urlopen(self.url,
+                                        context=parent.session.config.ssl_context)
+        try:
+            markup = handle.read()
+        finally:
+            handle.close()
+
+        if test_type not in TEST_TYPES:
+            raise ValueError('Unrecognized test type: "%s"' % test_type)
+
+        parsed = html5lib.parse(markup, namespaceHTMLElements=False)
+        name = None
+        self.expected = None
+
+        for element in parsed.iter():
+            if not name and element.tag == 'title':
+                name = element.text
+                continue
+            if element.tag == 'script':
+                if element.attrib.get('id') == 'expected':
+                    try:
+                        self.expected = json.loads(element.text)
+                    except ValueError:
+                        print("Failed parsing JSON in %s" % filename)
+                        raise
+
+        if not name:
+            raise ValueError('No name found in %s add a <title> element' % filename)
+        elif self.type == 'functional':
+            if not self.expected:
+                raise ValueError('Functional tests must specify expected report data')
+        elif self.type == 'unit' and self.expected:
+            raise ValueError('Unit tests must not specify expected report data')
+
+        # Ensure that distinct items have distinct fspath attributes.
+        # This is necessary because pytest has an internal cache keyed on it,
+        # and only the first test with any given fspath will be run.
+        #
+        # This cannot use super(HTMLItem, self).__init__(..) because only the
+        # Collector constructor takes the fspath argument.
+        pytest.Item.__init__(self, name, parent)
+        pytest.Collector.__init__(self, name, parent, fspath=py.path.local(filename))
+
+
+    def reportinfo(self):
+        return self.fspath, None, self.url
+
+    def repr_failure(self, excinfo):
+        return pytest.Collector.repr_failure(self, excinfo)
+
+    def runtest(self):
+        if self.type == 'unit':
+            self._run_unit_test()
+        elif self.type == 'functional':
+            self._run_functional_test()
+        else:
+            raise NotImplementedError
+
+    def _run_unit_test(self):
+        driver = self.session.config.driver
+        server = self.session.config.server
+
+        driver.url = server.url(HARNESS)
+
+        actual = driver.execute_async_script(
+            'runTest("%s", "foo", arguments[0])' % self.url
+        )
+
+        summarized = _summarize(copy.deepcopy(actual))
+
+        print(json.dumps(summarized, indent=2))
+
+        assert summarized[u'summarized_status'][u'status_string'] == u'OK', summarized[u'summarized_status'][u'message']
+        for test in summarized[u'summarized_tests']:
+            msg = "%s\n%s" % (test[u'name'], test[u'message'])
+            assert test[u'status_string'] == u'PASS', msg
+
+    def _run_functional_test(self):
+        driver = self.session.config.driver
+        server = self.session.config.server
+
+        driver.url = server.url(HARNESS)
+
+        test_url = self.url
+        actual = driver.execute_async_script('runTest("%s", "foo", arguments[0])' % test_url)
+
+        print(json.dumps(actual, indent=2))
+
+        summarized = _summarize(copy.deepcopy(actual))
+
+        print(json.dumps(summarized, indent=2))
+
+        # Test object ordering is not guaranteed. This weak assertion verifies
+        # that the indices are unique and sequential
+        indices = [test_obj.get('index') for test_obj in actual['tests']]
+        self._assert_sequence(indices)
+
+        self.expected[u'summarized_tests'].sort(key=lambda test_obj: test_obj.get('name'))
+
+        # Make asserts opt-in for now
+        if "summarized_asserts" not in self.expected:
+            del summarized["summarized_asserts"]
+        else:
+            # We can't be sure of the order of asserts even within the same test
+            # although we could also check for the failing assert being the final
+            # one
+            for obj in [summarized, self.expected]:
+                obj["summarized_asserts"].sort(
+                    key=lambda x: (x["test"] or "", x["status"], x["assert_name"], tuple(x["args"])))
+
+        assert summarized == self.expected
+
+    @staticmethod
+    def _assert_sequence(nums):
+        if nums and len(nums) > 0:
+            assert nums == list(range(1, nums[-1] + 1))
diff --git a/test/wpt/tests/resources/test/harness.html b/test/wpt/tests/resources/test/harness.html
new file mode 100644
index 0000000..5ee0f28
--- /dev/null
+++ b/test/wpt/tests/resources/test/harness.html
@@ -0,0 +1,26 @@
+<!DOCTYPE html>
+<html>
+  <head>
+    <meta http-equiv="Content-Type" content="text/html; charset=utf-8">
+  </head>
+  <body>
+    <script>
+function runTest(url, id, done) {
+  var child;
+
+  function onMessage(event) {
+    if (!event.data || event.data.type !== 'complete') {
+      return;
+    }
+
+    window.removeEventListener('message', onMessage);
+    child.close();
+    done(event.data);
+  }
+  window.addEventListener('message', onMessage);
+
+  window.child = child = window.open(url, id);
+}
+    </script>
+  </body>
+</html>
diff --git a/test/wpt/tests/resources/test/idl-helper.js b/test/wpt/tests/resources/test/idl-helper.js
new file mode 100644
index 0000000..2b73527
--- /dev/null
+++ b/test/wpt/tests/resources/test/idl-helper.js
@@ -0,0 +1,24 @@
+"use strict";
+
+var typedefFrom = interfaceFrom;
+var dictionaryFrom = interfaceFrom;
+function interfaceFrom(i) {
+    var idl = new IdlArray();
+    idl.add_idls(i);
+    for (var prop in idl.members) {
+        return idl.members[prop];
+    }
+}
+
+function memberFrom(m) {
+    var idl = new IdlArray();
+    idl.add_idls('interface A { ' + m + '; };');
+    return idl.members["A"].members[0];
+}
+
+function typeFrom(type) {
+    var ast = WebIDL2.parse('interface Foo { ' + type + ' a(); };');
+    ast = ast[0]; // get the first fragment
+    ast = ast.members[0]; // get the first member
+    return ast.idlType; // get the type of the first field
+}
diff --git a/test/wpt/tests/resources/test/nested-testharness.js b/test/wpt/tests/resources/test/nested-testharness.js
new file mode 100644
index 0000000..d97c156
--- /dev/null
+++ b/test/wpt/tests/resources/test/nested-testharness.js
@@ -0,0 +1,80 @@
+'use strict';
+
+/**
+ * Execute testharness.js and one or more scripts in an iframe. Report the
+ * results of the execution.
+ *
+ * @param {...function|...string} bodies - a function body. If specified as a
+ *                                         function object, it will be
+ *                                         serialized to a string using the
+ *                                         built-in
+ *                                         `Function.prototype.toString` prior
+ *                                         to inclusion in the generated
+ *                                         iframe.
+ *
+ * @returns {Promise} eventual value describing the result of the test
+ *                    execution; the summary object has two properties:
+ *                    `harness` (a string describing the harness status) and
+ *                    `tests` (an object whose "own" property names are the
+ *                    titles of the defined sub-tests and whose associated
+ *                    values are the subtest statuses).
+ */
+function makeTest(...bodies) {
+  const closeScript = '<' + '/script>';
+  let src = `
+<!DOCTYPE HTML>
+<html>
+<head>
+<title>Document title</title>
+<script src="/resources/testharness.js?${Math.random()}">${closeScript}
+</head>
+
+<body>
+<div id="log"></div>`;
+  bodies.forEach((body) => {
+    src += '<script>(' + body + ')();' + closeScript;
+  });
+
+  const iframe = document.createElement('iframe');
+
+  document.body.appendChild(iframe);
+  iframe.contentDocument.write(src);
+
+  return new Promise((resolve) => {
+    window.addEventListener('message', function onMessage(e) {
+      if (e.source !== iframe.contentWindow) {
+        return;
+      }
+      if (!e.data || e.data.type !=='complete') {
+        return;
+      }
+      window.removeEventListener('message', onMessage);
+      resolve(e.data);
+    });
+
+    iframe.contentDocument.close();
+  }).then(({ tests, status }) => {
+    const summary = {
+      harness: getEnumProp(status, status.status),
+      tests: {}
+    };
+
+    tests.forEach((test) => {
+      summary.tests[test.name] = getEnumProp(test, test.status);
+    });
+
+    return summary;
+  });
+}
+
+function getEnumProp(object, value) {
+  for (let property in object) {
+    if (!/^[A-Z]+$/.test(property)) {
+      continue;
+    }
+
+    if (object[property] === value) {
+      return property;
+    }
+  }
+}
diff --git a/test/wpt/tests/resources/test/requirements.txt b/test/wpt/tests/resources/test/requirements.txt
new file mode 100644
index 0000000..95d87c3
--- /dev/null
+++ b/test/wpt/tests/resources/test/requirements.txt
@@ -0,0 +1 @@
+html5lib==1.1
diff --git a/test/wpt/tests/resources/test/tests/functional/abortsignal.html b/test/wpt/tests/resources/test/tests/functional/abortsignal.html
new file mode 100644
index 0000000..e6080e9
--- /dev/null
+++ b/test/wpt/tests/resources/test/tests/functional/abortsignal.html
@@ -0,0 +1,49 @@
+<!DOCTYPE html>
+<title>Test#get_signal</title>
+<script src="/resources/testharness.js"></script>
+<script src="/resources/testharnessreport.js"></script>
+<script>
+  "use strict";
+
+  setup(() => {
+    assert_implements_optional(window.AbortController, "No AbortController");
+  });
+
+  let signal;
+  let observed = false;
+
+  test(t => {
+    signal = t.get_signal();
+    assert_true(signal instanceof AbortSignal, "Returns an abort signal");
+    assert_false(signal.aborted, "Signal should not be aborted before test end");
+    signal.onabort = () => observed = true;
+  }, "t.signal existence");
+
+  test(t => {
+    assert_true(signal.aborted, "Signal should be aborted after test end");
+    assert_true(observed, "onabort should have been called");
+  }, "t.signal.aborted");
+</script>
+<script type="text/json" id="expected">
+{
+  "summarized_status": {
+    "message": null,
+    "status_string": "OK"
+  },
+  "summarized_tests": [
+    {
+      "message": null,
+      "name": "t.signal existence",
+      "properties": {},
+      "status_string": "PASS"
+    },
+    {
+      "message": null,
+      "name": "t.signal.aborted",
+      "properties": {},
+      "status_string": "PASS"
+    }
+  ],
+  "type": "complete"
+}
+</script>
diff --git a/test/wpt/tests/resources/test/tests/functional/add_cleanup.html b/test/wpt/tests/resources/test/tests/functional/add_cleanup.html
new file mode 100644
index 0000000..468319f
--- /dev/null
+++ b/test/wpt/tests/resources/test/tests/functional/add_cleanup.html
@@ -0,0 +1,91 @@
+<!DOCTYPE HTML>
+<html>
+<head>
+<title>Test#add_cleanup</title>
+<script src="/resources/testharness.js"></script>
+<script src="/resources/testharnessreport.js"></script>
+</head>
+<body>
+<div id="log"></div>
+<script>
+"use strict";
+
+var log_sync;
+test(function(t) {
+  log_sync = "";
+  t.add_cleanup(function() { log_sync += "1"; });
+  t.add_cleanup(function() { log_sync += "2"; });
+  t.add_cleanup(function() { log_sync += "3"; });
+  t.add_cleanup(function() { log_sync += "4"; });
+  t.add_cleanup(function() { log_sync += "5"; });
+  log_sync += "0";
+}, "probe synchronous");
+
+test(function() {
+  if (log_sync !== "012345") {
+    throw new Error("Expected: '012345'. Actual: '" + log_sync + "'.");
+  }
+}, "Cleanup methods are invoked exactly once and in the expected sequence.");
+
+var complete, log_async;
+async_test(function(t) {
+  complete = t.step_func(function() {
+    if (log_async !== "012") {
+      throw new Error("Expected: '012'. Actual: '" + log_async + "'.");
+    }
+
+    t.done();
+  });
+}, "Cleanup methods are invoked following the completion of asynchronous tests");
+
+async_test(function(t) {
+  log_async = "";
+  t.add_cleanup(function() { log_async += "1"; });
+
+  setTimeout(t.step_func(function() {
+    t.add_cleanup(function() {
+      log_async += "2";
+      complete();
+    });
+    log_async += "0";
+    t.done();
+  }), 0);
+}, "probe asynchronous");
+</script>
+<script type="text/json" id="expected">
+{
+  "summarized_status": {
+    "status_string": "OK",
+    "message": null
+  },
+  "summarized_tests": [
+    {
+      "status_string": "PASS",
+      "name": "Cleanup methods are invoked exactly once and in the expected sequence.",
+      "properties": {},
+      "message": null
+    },
+    {
+      "status_string": "PASS",
+      "name": "Cleanup methods are invoked following the completion of asynchronous tests",
+      "properties": {},
+      "message": null
+    },
+    {
+      "status_string": "PASS",
+      "name": "probe asynchronous",
+      "properties": {},
+      "message": null
+    },
+    {
+      "status_string": "PASS",
+      "name": "probe synchronous",
+      "properties": {},
+      "message": null
+    }
+  ],
+  "type": "complete"
+}
+</script>
+</body>
+</html>
diff --git a/test/wpt/tests/resources/test/tests/functional/add_cleanup_async.html b/test/wpt/tests/resources/test/tests/functional/add_cleanup_async.html
new file mode 100644
index 0000000..07ade4b
--- /dev/null
+++ b/test/wpt/tests/resources/test/tests/functional/add_cleanup_async.html
@@ -0,0 +1,85 @@
+<!DOCTYPE HTML>
+<html>
+<head>
+<title>Test#add_cleanup with Promise-returning functions</title>
+<script src="../../../testharness.js"></script>
+<script src="../../../testharnessreport.js"></script>
+</head>
+<body>
+<div id="log"></div>
+
+<script>
+"use strict";
+var completeCount = 0;
+var counts = {
+    afterTick: null,
+    afterFirst: null
+};
+
+add_result_callback(function(result_t) {
+  completeCount += 1;
+});
+
+promise_test(function(t) {
+  t.add_cleanup(function() {
+    return new Promise(function(resolve) {
+      setTimeout(function() {
+        counts.afterTick = completeCount;
+        resolve();
+      }, 0);
+    });
+  });
+  t.add_cleanup(function() {
+    return new Promise(function(resolve) {
+
+      setTimeout(function() {
+        counts.afterFirst = completeCount;
+        resolve();
+      }, 0);
+    });
+  });
+
+  return Promise.resolve();
+}, 'promise_test with asynchronous cleanup');
+
+promise_test(function() {
+  assert_equals(
+    counts.afterTick,
+    0,
+    "test is not asynchronously considered 'complete'"
+  );
+  assert_equals(
+    counts.afterFirst,
+    0,
+    "test is not considered 'complete' following fulfillment of first promise"
+  );
+  assert_equals(completeCount, 1);
+
+  return Promise.resolve();
+}, "synchronously-defined promise_test");
+</script>
+<script type="text/json" id="expected">
+{
+  "summarized_status": {
+    "status_string": "OK",
+    "message": null
+  },
+  "summarized_tests": [
+    {
+      "status_string": "PASS",
+      "name": "promise_test with asynchronous cleanup",
+      "message": null,
+      "properties": {}
+    },
+    {
+      "status_string": "PASS",
+      "name": "synchronously-defined promise_test",
+      "message": null,
+      "properties": {}
+    }
+  ],
+  "type": "complete"
+}
+</script>
+</body>
+</html>
diff --git a/test/wpt/tests/resources/test/tests/functional/add_cleanup_async_bad_return.html b/test/wpt/tests/resources/test/tests/functional/add_cleanup_async_bad_return.html
new file mode 100644
index 0000000..867bde2
--- /dev/null
+++ b/test/wpt/tests/resources/test/tests/functional/add_cleanup_async_bad_return.html
@@ -0,0 +1,50 @@
+<!DOCTYPE HTML>
+<html>
+<head>
+<title>Test#add_cleanup with non-thenable-returning function</title>
+<script src="../../../testharness.js"></script>
+<script src="../../../testharnessreport.js"></script>
+</head>
+<body>
+<div id="log"></div>
+
+<script>
+"use strict";
+
+promise_test(function(t) {
+  t.add_cleanup(function() {});
+  t.add_cleanup(function() {
+    return { then: 9 };
+  });
+  t.add_cleanup(function() { return Promise.resolve(); });
+
+  return Promise.resolve();
+}, "promise_test that returns a non-thenable object in one \"cleanup\" callback");
+
+promise_test(function() {}, "The test runner is in an unpredictable state ('NOT RUN')");
+</script>
+<script type="text/json" id="expected">
+{
+  "summarized_status": {
+    "status_string": "ERROR",
+    "message": "Test named 'promise_test that returns a non-thenable object in one \"cleanup\" callback' specified 3 'cleanup' functions, and 1 returned a non-thenable value."
+  },
+  "summarized_tests": [
+    {
+      "status_string": "NOTRUN",
+      "name": "The test runner is in an unpredictable state ('NOT RUN')",
+      "message": null,
+      "properties": {}
+    },
+    {
+      "status_string": "PASS",
+      "name": "promise_test that returns a non-thenable object in one \"cleanup\" callback",
+      "message": null,
+      "properties": {}
+    }
+  ],
+  "type": "complete"
+}
+</script>
+</body>
+</html>
diff --git a/test/wpt/tests/resources/test/tests/functional/add_cleanup_async_rejection.html b/test/wpt/tests/resources/test/tests/functional/add_cleanup_async_rejection.html
new file mode 100644
index 0000000..e51465e
--- /dev/null
+++ b/test/wpt/tests/resources/test/tests/functional/add_cleanup_async_rejection.html
@@ -0,0 +1,94 @@
+<!DOCTYPE HTML>
+<html>
+<head>
+<title>Test#add_cleanup with Promise-returning functions (rejection handling)</title>
+<script src="../../../testharness.js"></script>
+<script src="../../../testharnessreport.js"></script>
+</head>
+<body>
+<div id="log"></div>
+
+<script>
+"use strict";
+var resolve, reject;
+var completeCount = 0;
+add_result_callback(function(result_t) {
+  completeCount += 1;
+});
+promise_test(function(t) {
+  t.add_cleanup(function() {
+    return new Promise(function(_, _reject) { reject = _reject; });
+  });
+  t.add_cleanup(function() {
+    return new Promise(function(_resolve) { resolve = _resolve; });
+  });
+
+  // The following cleanup function defines empty tests so that the reported
+  // data demonstrates the intended run-time behavior without relying on the
+  // test harness's handling of errors during test cleanup (which is tested
+  // elsewhere).
+  t.add_cleanup(function() {
+    if (completeCount === 0) {
+      promise_test(
+        function() {},
+        "test is not asynchronously considered 'complete' ('NOT RUN')"
+      );
+    }
+
+    reject();
+
+    setTimeout(function() {
+      if (completeCount === 0) {
+        promise_test(
+          function() {},
+          "test is not considered 'complete' following rejection of first " +
+          "promise ('NOT RUN')"
+        );
+      }
+
+      resolve();
+    }, 0);
+  });
+
+  return Promise.resolve();
+}, "promise_test with asynchronous cleanup including rejection");
+
+promise_test(function() {}, "synchronously-defined test ('NOT RUN')");
+</script>
+<script type="text/json" id="expected">
+{
+  "summarized_status": {
+    "status_string": "ERROR",
+    "message": "Test named 'promise_test with asynchronous cleanup including rejection' specified 3 'cleanup' functions, and 1 failed."
+  },
+  "summarized_tests": [
+    {
+      "status_string": "PASS",
+      "name": "promise_test with asynchronous cleanup including rejection",
+      "message": null,
+      "properties": {}
+    },
+    {
+      "status_string": "NOTRUN",
+      "name": "synchronously-defined test ('NOT RUN')",
+      "message": null,
+      "properties": {}
+    },
+    {
+      "status_string": "NOTRUN",
+      "name": "test is not asynchronously considered 'complete' ('NOT RUN')",
+      "message": null,
+      "properties": {}
+    },
+    {
+      "status_string": "NOTRUN",
+      "name": "test is not considered 'complete' following rejection of first promise ('NOT RUN')",
+      "message": null,
+      "properties": {}
+    }
+  ],
+  "type": "complete"
+}
+</script>
+</body>
+</html>
diff --git a/test/wpt/tests/resources/test/tests/functional/add_cleanup_async_rejection_after_load.html b/test/wpt/tests/resources/test/tests/functional/add_cleanup_async_rejection_after_load.html
new file mode 100644
index 0000000..f9b2846
--- /dev/null
+++ b/test/wpt/tests/resources/test/tests/functional/add_cleanup_async_rejection_after_load.html
@@ -0,0 +1,52 @@
+<!DOCTYPE HTML>
+<html>
+<head>
+<title>Test#add_cleanup with Promise-returning functions (rejection handling following "load" event)</title>
+</head>
+<body>
+<h1>Promise Tests</h1>
+<p>This test demonstrates the use of <tt>promise_test</tt>. Assumes ECMAScript 6
+Promise support. Some failures are expected.</p>
+<div id="log"></div>
+<script src="../../../testharness.js"></script>
+<script src="../../../testharnessreport.js"></script>
+<script>
+promise_test(function(t) {
+  t.add_cleanup(function() {
+    return Promise.reject(new Error("foo"));
+  });
+
+  return new Promise((resolve) => {
+    document.addEventListener("DOMContentLoaded", function() {
+      setTimeout(resolve, 0)
+    });
+  });
+}, "Test with failing cleanup that completes after DOMContentLoaded event");
+
+promise_test(function(t) {
+  return Promise.resolve();
+}, "Test that should not be run due to invalid harness state ('NOT RUN')");
+</script>
+<script type="text/json" id="expected">
+{
+  "summarized_status": {
+    "status_string": "ERROR",
+    "message": "Test named 'Test with failing cleanup that completes after DOMContentLoaded event' specified 1 'cleanup' function, and 1 failed."
+  },
+  "summarized_tests": [
+    {
+      "status_string": "NOTRUN",
+      "name": "Test that should not be run due to invalid harness state ('NOT RUN')",
+      "message": null,
+      "properties": {}
+    },
+    {
+      "status_string": "PASS",
+      "name": "Test with failing cleanup that completes after DOMContentLoaded event",
+      "message": null,
+      "properties": {}
+    }
+  ],
+  "type": "complete"
+}
+</script>
diff --git a/test/wpt/tests/resources/test/tests/functional/add_cleanup_async_timeout.html b/test/wpt/tests/resources/test/tests/functional/add_cleanup_async_timeout.html
new file mode 100644
index 0000000..429536c
--- /dev/null
+++ b/test/wpt/tests/resources/test/tests/functional/add_cleanup_async_timeout.html
@@ -0,0 +1,57 @@
+<!DOCTYPE HTML>
+<html>
+<head>
+<title>Test#add_cleanup with Promise-returning functions (timeout handling)</title>
+<script src="../../../testharness.js"></script>
+<script src="../../../testharnessreport.js"></script>
+</head>
+<body>
+<div id="log"></div>
+<script>
+"use strict";
+
+promise_test(function(t) {
+  t.add_cleanup(function() {
+    return Promise.resolve();
+  });
+
+  t.add_cleanup(function() {
+    return new Promise(function() {});
+  });
+
+  t.add_cleanup(function() {});
+
+  t.add_cleanup(function() {
+    return new Promise(function() {});
+  });
+
+  return Promise.resolve();
+}, "promise_test with asynchronous cleanup");
+
+promise_test(function() {}, "promise_test following timed out cleanup ('NOT RUN')");
+</script>
+<script type="text/json" id="expected">
+{
+  "summarized_status": {
+    "status_string": "ERROR",
+    "message": "Timeout while running cleanup for test named \"promise_test with asynchronous cleanup\"."
+  },
+  "summarized_tests": [
+    {
+      "status_string": "NOTRUN",
+      "name": "promise_test following timed out cleanup ('NOT RUN')",
+      "message": null,
+      "properties": {}
+    },
+    {
+      "status_string": "PASS",
+      "name": "promise_test with asynchronous cleanup",
+      "message": null,
+      "properties": {}
+    }
+  ],
+  "type": "complete"
+}
+</script>
+</body>
+</html>
diff --git a/test/wpt/tests/resources/test/tests/functional/add_cleanup_bad_return.html b/test/wpt/tests/resources/test/tests/functional/add_cleanup_bad_return.html
new file mode 100644
index 0000000..3cfb28a
--- /dev/null
+++ b/test/wpt/tests/resources/test/tests/functional/add_cleanup_bad_return.html
@@ -0,0 +1,61 @@
+<!DOCTYPE HTML>
+<html>
+<head>
+<title>Test#add_cleanup with value-returning function</title>
+<script src="../../../testharness.js"></script>
+<script src="../../../testharnessreport.js"></script>
+</head>
+<body>
+<div id="log"></div>
+<script>
+"use strict";
+
+test(function(t) {
+  t.add_cleanup(function() {});
+  t.add_cleanup(function() { return null; });
+  t.add_cleanup(function() {
+    test(
+      function() {},
+      "The test runner is in an unpredictable state #1 ('NOT RUN')"
+    );
+
+    throw new Error();
+  });
+  t.add_cleanup(function() { return 4; });
+  t.add_cleanup(function() { return { then: function() {} }; });
+  t.add_cleanup(function() {});
+}, "Test that returns a value in three \"cleanup\" functions");
+
+test(function() {}, "The test runner is in an unpredictable state #2 ('NOT RUN')");
+</script>
+<script type="text/json" id="expected">
+{
+  "summarized_status": {
+    "status_string": "ERROR",
+    "message": "Test named 'Test that returns a value in three \"cleanup\" functions' specified 6 'cleanup' functions, and 1 failed, and 3 returned a non-undefined value."
+  },
+  "summarized_tests": [
+    {
+      "status_string": "PASS",
+      "name": "Test that returns a value in three \"cleanup\" functions",
+      "properties": {},
+      "message": null
+    },
+    {
+      "status_string": "NOTRUN",
+      "name": "The test runner is in an unpredictable state #1 ('NOT RUN')",
+      "message": null,
+      "properties": {}
+    },
+    {
+      "status_string": "NOTRUN",
+      "name": "The test runner is in an unpredictable state #2 ('NOT RUN')",
+      "message": null,
+      "properties": {}
+    }
+  ],
+  "type": "complete"
+}
+</script>
+</body>
+</html>
diff --git a/test/wpt/tests/resources/test/tests/functional/add_cleanup_count.html b/test/wpt/tests/resources/test/tests/functional/add_cleanup_count.html
new file mode 100644
index 0000000..2c9b51c
--- /dev/null
+++ b/test/wpt/tests/resources/test/tests/functional/add_cleanup_count.html
@@ -0,0 +1,39 @@
+<!DOCTYPE HTML>
+<html>
+<head>
+<title>Test#add_cleanup reported count</title>
+<script src="../../../testharness.js"></script>
+<script src="../../../testharnessreport.js"></script>
+</head>
+<body>
+<div id="log"></div>
+
+<script>
+promise_test(function(t) {
+    t.add_cleanup(function() {});
+    t.add_cleanup(function() {});
+    t.add_cleanup(function() { throw new Error(); });
+    new EventWatcher(t, document.body, []);
+
+    return Promise.resolve();
+}, 'test with 3 user-defined cleanup functions');
+</script>
+<script type="text/json" id="expected">
+{
+  "summarized_status": {
+    "status_string": "ERROR",
+    "message": "Test named 'test with 3 user-defined cleanup functions' specified 3 'cleanup' functions, and 1 failed."
+  },
+  "summarized_tests": [
+    {
+      "status_string": "PASS",
+      "name": "test with 3 user-defined cleanup functions",
+      "message": null,
+      "properties": {}
+    }
+  ],
+  "type": "complete"
+}
+</script>
+</body>
+</html>
diff --git a/test/wpt/tests/resources/test/tests/functional/add_cleanup_err.html b/test/wpt/tests/resources/test/tests/functional/add_cleanup_err.html
new file mode 100644
index 0000000..60357c6
--- /dev/null
+++ b/test/wpt/tests/resources/test/tests/functional/add_cleanup_err.html
@@ -0,0 +1,45 @@
+<!DOCTYPE HTML>
+<html>
+<head>
+<title>Test#add_cleanup: error</title>
+<script src="../../../testharness.js"></script>
+<script src="../../../testharnessreport.js"></script>
+</head>
+<body>
+<div id="log"></div>
+<script>
+"use strict";
+
+test(function(t) {
+  t.add_cleanup(function() {
+    throw new Error('exception in cleanup function');
+  });
+}, "Exception in cleanup function causes harness failure.");
+
+test(function() {}, "This test should not be run.");
+</script>
+<script type="text/json" id="expected">
+{
+  "summarized_status": {
+    "status_string": "ERROR",
+    "message": "Test named 'Exception in cleanup function causes harness failure.' specified 1 'cleanup' function, and 1 failed."
+  },
+  "summarized_tests": [
+    {
+      "status_string": "PASS",
+      "name": "Exception in cleanup function causes harness failure.",
+      "properties": {},
+      "message": null
+    },
+    {
+      "status_string": "NOTRUN",
+      "name": "This test should not be run.",
+      "properties": {},
+      "message": null
+    }
+  ],
+  "type": "complete"
+}
+</script>
+</body>
+</html>
diff --git a/test/wpt/tests/resources/test/tests/functional/add_cleanup_err_multi.html b/test/wpt/tests/resources/test/tests/functional/add_cleanup_err_multi.html
new file mode 100644
index 0000000..80ba1b4
--- /dev/null
+++ b/test/wpt/tests/resources/test/tests/functional/add_cleanup_err_multi.html
@@ -0,0 +1,52 @@
+<!DOCTYPE HTML>
+<html>
+<head>
+<title>Test#add_cleanup: multiple functions with one in error</title>
+<script src="../../../testharness.js"></script>
+<script src="../../../testharnessreport.js"></script>
+</head>
+<body>
+<div id="log"></div>
+
+<script>
+"use strict";
+
+test(function(t) {
+    t.add_cleanup(function() {
+      throw new Error("exception in cleanup function");
+    });
+
+    // The following cleanup function defines a test so that the reported
+    // data demonstrates the intended run-time behavior, i.e. that
+    // `testharness.js` invokes all cleanup functions even when one or more
+    // throw errors.
+    t.add_cleanup(function() {
+      test(function() {}, "Verification test");
+    });
+  }, "Test with multiple cleanup functions");
+</script>
+<script type="text/json" id="expected">
+{
+  "summarized_status": {
+    "status_string": "ERROR",
+    "message": "Test named 'Test with multiple cleanup functions' specified 2 'cleanup' functions, and 1 failed."
+  },
+  "summarized_tests": [
+    {
+      "status_string": "PASS",
+      "name": "Test with multiple cleanup functions",
+      "properties": {},
+      "message": null
+    },
+    {
+      "status_string": "NOTRUN",
+      "name": "Verification test",
+      "properties": {},
+      "message": null
+    }
+  ],
+  "type": "complete"
+}
+</script>
+</body>
+</html>
diff --git a/test/wpt/tests/resources/test/tests/functional/add_cleanup_sync_queue.html b/test/wpt/tests/resources/test/tests/functional/add_cleanup_sync_queue.html
new file mode 100644
index 0000000..0a61503
--- /dev/null
+++ b/test/wpt/tests/resources/test/tests/functional/add_cleanup_sync_queue.html
@@ -0,0 +1,55 @@
+<!DOCTYPE HTML>
+<html>
+<head>
+<title>Test#add_cleanup: queuing tests</title>
+<script src="../../../testharness.js"></script>
+<script src="../../../testharnessreport.js"></script>
+</head>
+<body>
+<div id="log"></div>
+
+<script>
+"use strict";
+var firstCleaned = false;
+
+promise_test(function(t) {
+  promise_test(function() {
+    assert_true(
+      firstCleaned, "should not execute until first test is complete"
+    );
+
+    return Promise.resolve();
+  }, "test defined when no tests are queued, but one test is executing");
+
+  t.add_cleanup(function() {
+    firstCleaned = true;
+  });
+
+  return Promise.resolve();
+}, "Test with a 'cleanup' function");
+</script>
+<script type="text/json" id="expected">
+{
+  "summarized_status": {
+    "message": null,
+    "status_string": "OK"
+  },
+  "summarized_tests": [
+    {
+      "message": null,
+      "name": "Test with a 'cleanup' function",
+      "status_string": "PASS",
+      "properties": {}
+    },
+    {
+      "message": null,
+      "name": "test defined when no tests are queued, but one test is executing",
+      "status_string": "PASS",
+      "properties": {}
+    }
+  ],
+  "type": "complete"
+}
+</script>
+</body>
+</html>
diff --git a/test/wpt/tests/resources/test/tests/functional/api-tests-1.html b/test/wpt/tests/resources/test/tests/functional/api-tests-1.html
new file mode 100644
index 0000000..9de875b
--- /dev/null
+++ b/test/wpt/tests/resources/test/tests/functional/api-tests-1.html
@@ -0,0 +1,991 @@
+<!DOCTYPE HTML>
+<html>
+<head>
+<title>Sample HTML5 API Tests</title>
+<meta name="timeout" content="6000">
+</head>
+<body onload="load_test_attr.done()">
+<h1>Sample HTML5 API Tests</h1>
+<div id="log"></div>
+<script src="/resources/testharness.js"></script>
+<script src="/resources/testharnessreport.js"></script>
+<script>
+    setup_run = false;
+    setup(function() {
+            setup_run = true;
+          });
+    test(function() {assert_true(setup_run)}, "Setup function ran");
+
+    // Two examples for testing events from handler and attributes
+    var load_test_event = async_test("window onload event fires when set from the handler");
+
+    function windowLoad()
+    {
+        load_test_event.done();
+    }
+    on_event(window, "load", windowLoad);
+
+    test(function() {
+        var sequence = [];
+        var outer = document.createElement("div");
+        var inner = document.createElement("div");
+        outer.appendChild(inner);
+        document.body.appendChild(outer);
+        inner.addEventListener("click", function() {
+            sequence.push("inner");
+        }, false);
+
+        on_event(outer, "click", function() {
+            sequence.push("outer");
+        });
+        inner.click();
+
+        assert_array_equals(sequence, ["inner", "outer"]);
+    }, "on_event does not use event capture");
+
+    // see the body onload below
+    var load_test_attr = async_test("body element fires the onload event set from the attribute");
+</script>
+<script>
+    function bodyElement()
+    {
+        assert_equals(document.body, document.getElementsByTagName("body")[0]);
+    }
+    test(bodyElement, "document.body should be the first body element in the document");
+
+    test(function() {
+        assert_equals(1,1);
+        assert_equals(NaN, NaN, "NaN case");
+        assert_equals(0, 0, "Zero case");
+    }, "assert_equals tests")
+
+    test(function() {
+        assert_equals(-0, 0, "Zero case");
+    }, "assert_equals tests expected to fail")
+
+    test(function() {
+        assert_not_equals({}, {}, "object case");
+        assert_not_equals(-0, 0, "Zero case");
+    }, "assert_not_equals tests")
+
+    function testAssertPass()
+    {
+        assert_true(true);
+    }
+    test(testAssertPass, "assert_true expected to pass");
+
+    function testAssertFalse()
+    {
+        assert_true(false, "false should not be true");
+    }
+    test(testAssertFalse, "assert_true expected to fail");
+
+    function basicAssertArrayEquals()
+    {
+        assert_array_equals([1, NaN], [1, NaN], "[1, NaN] is equal to [1, NaN]");
+    }
+    test(basicAssertArrayEquals, "basic assert_array_equals test");
+
+    function assertArrayEqualsUndefined()
+    {
+        assert_array_equals(undefined, [1], "undefined equals [1]?");
+    }
+    test(assertArrayEqualsUndefined, "assert_array_equals with first param undefined");
+
+    function assertArrayEqualsTrue()
+    {
+        assert_array_equals(true, [1], "true equals [1]?");
+    }
+    test(assertArrayEqualsTrue, "assert_array_equals with first param true");
+
+    function assertArrayEqualsFalse()
+    {
+        assert_array_equals(false, [1], "false equals [1]?");
+    }
+    test(assertArrayEqualsFalse, "assert_array_equals with first param false");
+
+    function assertArrayEqualsNull()
+    {
+        assert_array_equals(null, [1], "null equals [1]?");
+    }
+    test(assertArrayEqualsNull, "assert_array_equals with first param null");
+
+    function assertArrayEqualsNumeric()
+    {
+        assert_array_equals(1, [1], "1 equals [1]?");
+    }
+    test(assertArrayEqualsNumeric, "assert_array_equals with first param 1");
+
+    function basicAssertArrayApproxEquals()
+    {
+        assert_array_approx_equals([10, 11], [11, 10], 1, "[10, 11] is approximately (+/- 1) [11, 10]")
+    }
+    test(basicAssertArrayApproxEquals, "basic assert_array_approx_equals test");
+
+    function basicAssertApproxEquals()
+    {
+        assert_approx_equals(10, 11, 1, "10 is approximately (+/- 1) 11")
+    }
+    test(basicAssertApproxEquals, "basic assert_approx_equals test");
+
+    function basicAssertLessThan()
+    {
+        assert_less_than(10, 11, "10 is less than 11")
+    }
+    test(basicAssertApproxEquals, "basic assert_less_than test");
+
+    function basicAssertGreaterThan()
+    {
+        assert_greater_than(10, 11, "10 is not greater than 11");
+    }
+    test(basicAssertGreaterThan, "assert_greater_than expected to fail");
+
+    function basicAssertGreaterThanEqual()
+    {
+        assert_greater_than_equal(10, 10, "10 is greater than or equal to 10")
+    }
+    test(basicAssertGreaterThanEqual, "basic assert_greater_than_equal test");
+
+    function basicAssertLessThanEqual()
+    {
+        assert_greater_than_equal('10', 10, "'10' is not a number")
+    }
+    test(basicAssertLessThanEqual, "assert_less_than_equal expected to fail");
+
+    function testAssertInherits() {
+        var A = function(){this.a = "a"}
+        A.prototype = {b:"b"}
+        var a = new A();
+        assert_own_property(a, "a");
+        assert_not_own_property(a, "b", "unexpected property found: \"b\"");
+        assert_inherits(a, "b");
+    }
+    test(testAssertInherits, "test for assert[_not]_own_property and insert_inherits")
+
+    test(function()
+    {
+        var a = document.createElement("a")
+        var b = document.createElement("b")
+        assert_throws_dom("NOT_FOUND_ERR", function () {a.removeChild(b)});
+    }, "Test throw DOM exception")
+
+    test(function()
+    {
+        var a = document.createElement("a")
+        var b = document.createElement("b")
+        assert_throws_js(DOMException, function () {a.removeChild(b)});
+    }, "Test throw DOMException as JS exception expected to fail")
+
+    test(function()
+    {
+        assert_throws_js(SyntaxError, function () {document.querySelector("")});
+    }, "Test throw SyntaxError DOMException where JS SyntaxError expected; expected to fail")
+
+    test(function()
+    {
+        assert_throws_js(SyntaxError, function () {JSON.parse("{")});
+    }, "Test throw JS SyntaxError")
+
+    test(function()
+    {
+        assert_throws_dom("SyntaxError", function () {document.querySelector("")});
+    }, "Test throw DOM SyntaxError")
+
+    test(function()
+    {
+        var ifr = document.createElement("iframe");
+        document.body.appendChild(ifr);
+        this.add_cleanup(() => ifr.remove());
+        assert_throws_dom("SyntaxError", ifr.contentWindow.DOMException,
+                          function () {ifr.contentDocument.querySelector("")});
+    }, "Test throw DOM SyntaxError from subframe");
+
+    test(function()
+    {
+        var ifr = document.createElement("iframe");
+        document.body.appendChild(ifr);
+        this.add_cleanup(() => ifr.remove());
+        assert_throws_dom("SyntaxError",
+                          function () {ifr.contentDocument.querySelector("")});
+    }, "Test throw DOM SyntaxError from subframe with incorrect global expectation; expected to fail");
+
+    test(function()
+    {
+        var ifr = document.createElement("iframe");
+        document.body.appendChild(ifr);
+        this.add_cleanup(() => ifr.remove());
+        assert_throws_dom("SyntaxError", ifr.contentWindow.DOMException,
+                          function () {document.querySelector("")});
+    }, "Test throw DOM SyntaxError with incorrect expectation; expected to fail");
+
+    test(function()
+    {
+        assert_throws_dom("SyntaxError", function () {JSON.parse("{")});
+    }, "Test throw JS SyntaxError where SyntaxError DOMException expected; expected to fail")
+
+    test(function()
+    {
+        var a = document.createTextNode("a")
+        var b = document.createElement("b")
+        assert_throws_dom("NOT_FOUND_ERR", function () {a.appendChild(b)});
+    }, "Test throw DOM exception expected to fail")
+
+    test(function()
+    {
+        var e = new DOMException("I am not known", "TEST_ERROR_NO_SUCH_THING");
+        assert_throws_dom(0, function() {throw e});
+    }, "Test assert_throws_dom with ambiguous DOM-exception expected to Fail");
+
+    test(function()
+    {
+        var e = {code:0, name:"TEST_ERR", TEST_ERR:0};
+        e.constructor = DOMException;
+        assert_throws_dom("TEST_ERR", function() {throw e});
+    }, "Test assert_throws_dom with non-DOM-exception expected to Fail");
+
+    test(function()
+    {
+        var e = {code: DOMException.SYNTAX_ERR, name:"SyntaxError"};
+        e.constructor = DOMException;
+        assert_throws_dom(DOMException.SYNTAX_ERR, function() {throw e});
+    }, "Test assert_throws_dom with number code value expected to Pass");
+
+    test(function()
+    {
+        var e = new DOMException("Some message", "SyntaxError");
+        assert_throws_dom(DOMException.SYNTAX_ERR, function() {throw e});
+    }, "Test assert_throws_dom with number code value and real DOMException expected to Pass");
+
+    var t = async_test("Test step_func")
+    setTimeout(
+      t.step_func(
+        function () {
+          assert_true(true); t.done();
+        }), 0);
+
+    async_test(function(t) {
+        setTimeout(t.step_func(function (){assert_true(true); t.done();}), 0);
+    }, "Test async test with callback");
+
+    async_test(function() {
+        setTimeout(this.step_func(function (){assert_true(true); this.done();}), 0);
+    }, "Test async test with callback and `this` obj.");
+
+    async_test("test should timeout (fail) with the default of 2 seconds").step(function(){});
+
+    async_test("async test that is never started, should have status Not Run");
+
+
+    test(function(t) {
+             window.global = 1;
+             t.add_cleanup(function() {delete window.global});
+             assert_equals(window.global, 1);
+         },
+         "Test that defines a global and cleans it up");
+
+    test(function() {assert_equals(window.global, undefined)},
+         "Test that cleanup handlers from previous test ran");
+
+</script>
+<script type="text/json" id="expected">
+{
+  "summarized_status": {
+    "status_string": "TIMEOUT",
+    "message": null
+  },
+  "summarized_tests": [
+    {
+      "status_string": "PASS",
+      "name": "Setup function ran",
+      "message": null,
+      "properties": {}
+    },
+    {
+      "status_string": "FAIL",
+      "name": "Test assert_throws_dom with ambiguous DOM-exception expected to Fail",
+      "message": "Test bug: ambiguous DOMException code 0 passed to assert_throws_dom()",
+      "properties": {}
+    },
+    {
+      "status_string": "FAIL",
+      "name": "Test assert_throws_dom with non-DOM-exception expected to Fail",
+      "message": "Test bug: unrecognized DOMException code name or name \"TEST_ERR\" passed to assert_throws_dom()",
+      "properties": {}
+    },
+    {
+      "status_string": "PASS",
+      "name": "Test assert_throws_dom with number code value expected to Pass",
+      "message": null,
+      "properties": {}
+    },
+    {
+      "status_string": "PASS",
+      "name": "Test assert_throws_dom with number code value and real DOMException expected to Pass",
+      "message": null,
+      "properties": {}
+    },
+    {
+      "status_string": "PASS",
+      "name": "Test async test with callback",
+      "message": null,
+      "properties": {}
+    },
+    {
+      "status_string": "PASS",
+      "name": "Test async test with callback and `this` obj.",
+      "message": null,
+      "properties": {}
+    },
+    {
+      "status_string": "PASS",
+      "name": "Test step_func",
+      "message": null,
+      "properties": {}
+    },
+    {
+      "status_string": "PASS",
+      "name": "Test that cleanup handlers from previous test ran",
+      "message": null,
+      "properties": {}
+    },
+    {
+      "status_string": "PASS",
+      "name": "Test that defines a global and cleans it up",
+      "message": null,
+      "properties": {}
+    },
+    {
+      "status_string": "PASS",
+      "name": "Test throw DOM exception",
+      "message": null,
+      "properties": {}
+    },
+    {
+      "status_string": "FAIL",
+      "name": "Test throw DOMException as JS exception expected to fail",
+      "message": "assert_throws_js: function \"function DOMException() {\n    [native code]\n}\" is not an Error subtype",
+      "properties": {}
+    },
+    {
+      "status_string": "FAIL",
+      "name": "Test throw SyntaxError DOMException where JS SyntaxError expected; expected to fail",
+      "message": "assert_throws_js: function \"function () {document.querySelector(\"\")}\" threw object \"SyntaxError: Document.querySelector: '' is not a valid selector\" (\"SyntaxError\") expected instance of function \"function SyntaxError() {\n    [native code]\n}\" (\"SyntaxError\")",
+      "properties": {}
+    },
+    {
+      "status_string": "PASS",
+      "name": "Test throw JS SyntaxError",
+      "message": null,
+      "properties": {}
+    },
+    {
+      "status_string": "PASS",
+      "name": "Test throw DOM SyntaxError",
+      "message": null,
+      "properties": {}
+    },
+    {
+      "status_string": "PASS",
+      "name": "Test throw DOM SyntaxError from subframe",
+      "message": null,
+      "properties": {}
+    },
+    {
+      "status_string": "FAIL",
+      "name": "Test throw DOM SyntaxError from subframe with incorrect global expectation; expected to fail",
+      "message": "assert_throws_dom: function \"function () {ifr.contentDocument.querySelector(\"\")}\" threw an exception from the wrong global",
+      "properties": {}
+    },
+    {
+      "status_string": "FAIL",
+      "name": "Test throw DOM SyntaxError with incorrect expectation; expected to fail",
+      "message": "assert_throws_dom: function \"function () {document.querySelector(\"\")}\" threw an exception from the wrong global",
+      "properties": {}
+    },
+    {
+      "status_string": "FAIL",
+      "name": "Test throw JS SyntaxError where SyntaxError DOMException expected; expected to fail",
+      "message": "assert_throws_dom: function \"function () {JSON.parse(\"{\")}\" threw object \"SyntaxError: JSON.parse: end of data while reading object contents at line 1 column 2 of the JSON data\" that is not a DOMException SyntaxError: property \"code\" is equal to undefined, expected 12",
+      "properties": {}
+    },
+    {
+      "status_string": "FAIL",
+      "name": "Test throw DOM exception expected to fail",
+      "message": "assert_throws_dom: function \"function () {a.appendChild(b)}\" threw object \"HierarchyRequestError: Node.appendChild: Cannot add children to a Text\" that is not a DOMException NOT_FOUND_ERR: property \"code\" is equal to 3, expected 8",
+      "properties": {}
+    },
+    {
+      "status_string": "FAIL",
+      "name": "assert_array_equals with first param 1",
+      "message": "assert_array_equals: 1 equals [1]? value is 1, expected array",
+      "properties": {}
+    },
+    {
+      "status_string": "FAIL",
+      "name": "assert_array_equals with first param false",
+      "message": "assert_array_equals: false equals [1]? value is false, expected array",
+      "properties": {}
+    },
+    {
+      "status_string": "FAIL",
+      "name": "assert_array_equals with first param null",
+      "message": "assert_array_equals: null equals [1]? value is null, expected array",
+      "properties": {}
+    },
+    {
+      "status_string": "FAIL",
+      "name": "assert_array_equals with first param true",
+      "message": "assert_array_equals: true equals [1]? value is true, expected array",
+      "properties": {}
+    },
+    {
+      "status_string": "FAIL",
+      "name": "assert_array_equals with first param undefined",
+      "message": "assert_array_equals: undefined equals [1]? value is undefined, expected array",
+      "properties": {}
+    },
+    {
+      "status_string": "PASS",
+      "name": "assert_equals tests",
+      "message": null,
+      "properties": {}
+    },
+    {
+      "status_string": "FAIL",
+      "name": "assert_equals tests expected to fail",
+      "message": "assert_equals: Zero case expected 0 but got -0",
+      "properties": {}
+    },
+    {
+      "status_string": "FAIL",
+      "name": "assert_greater_than expected to fail",
+      "message": "assert_greater_than: 10 is not greater than 11 expected a number greater than 11 but got 10",
+      "properties": {}
+    },
+    {
+      "status_string": "FAIL",
+      "name": "assert_less_than_equal expected to fail",
+      "message": "assert_greater_than_equal: '10' is not a number expected a number but got a \"string\"",
+      "properties": {}
+    },
+    {
+      "status_string": "PASS",
+      "name": "assert_not_equals tests",
+      "message": null,
+      "properties": {}
+    },
+    {
+      "status_string": "FAIL",
+      "name": "assert_true expected to fail",
+      "message": "assert_true: false should not be true expected true got false",
+      "properties": {}
+    },
+    {
+      "status_string": "PASS",
+      "name": "assert_true expected to pass",
+      "message": null,
+      "properties": {}
+    },
+    {
+      "status_string": "NOTRUN",
+      "name": "async test that is never started, should have status Not Run",
+      "message": null,
+      "properties": {}
+    },
+    {
+      "status_string": "PASS",
+      "name": "basic assert_approx_equals test",
+      "message": null,
+      "properties": {}
+    },
+    {
+      "status_string": "PASS",
+      "name": "basic assert_array_approx_equals test",
+      "message": null,
+      "properties": {}
+    },
+    {
+      "status_string": "PASS",
+      "name": "basic assert_array_equals test",
+      "message": null,
+      "properties": {}
+    },
+    {
+      "status_string": "PASS",
+      "name": "basic assert_greater_than_equal test",
+      "message": null,
+      "properties": {}
+    },
+    {
+      "status_string": "PASS",
+      "name": "basic assert_less_than test",
+      "message": null,
+      "properties": {}
+    },
+    {
+      "status_string": "PASS",
+      "name": "body element fires the onload event set from the attribute",
+      "message": null,
+      "properties": {}
+    },
+    {
+      "status_string": "PASS",
+      "name": "document.body should be the first body element in the document",
+      "message": null,
+      "properties": {}
+    },
+    {
+      "status_string": "PASS",
+      "name": "test for assert[_not]_own_property and insert_inherits",
+      "message": null,
+      "properties": {}
+    },
+    {
+      "status_string": "TIMEOUT",
+      "name": "test should timeout (fail) with the default of 2 seconds",
+      "message": "Test timed out",
+      "properties": {}
+    },
+    {
+      "status_string": "PASS",
+      "name": "window onload event fires when set from the handler",
+      "message": null,
+      "properties": {}
+    },
+    {
+      "status_string": "PASS",
+      "name": "on_event does not use event capture",
+      "message": null,
+      "properties": {}
+    }
+  ],
+  "summarized_asserts": [
+    {
+      "assert_name": "assert_true",
+      "test": "Setup function ran",
+      "args": [
+        "true"
+      ],
+      "status": 0
+    },
+    {
+      "assert_name": "assert_array_equals",
+      "test": "on_event does not use event capture",
+      "args": [
+        "[\"inner\", \"outer\"]",
+        "[\"inner\", \"outer\"]"
+      ],
+      "status": 0
+    },
+    {
+      "assert_name": "assert_equals",
+      "test": "document.body should be the first body element in the document",
+      "args": [
+        "Element node <body onload=\"load_test_attr.done()\"> <h1>Sample HTML5 AP...",
+        "Element node <body onload=\"load_test_attr.done()\"> <h1>Sample HTML5 AP..."
+      ],
+      "status": 0
+    },
+    {
+      "assert_name": "assert_equals",
+      "test": "assert_equals tests",
+      "args": [
+        "1",
+        "1"
+      ],
+      "status": 0
+    },
+    {
+      "assert_name": "assert_equals",
+      "test": "assert_equals tests",
+      "args": [
+        "NaN",
+        "NaN",
+        "\"NaN case\""
+      ],
+      "status": 0
+    },
+    {
+      "assert_name": "assert_equals",
+      "test": "assert_equals tests",
+      "args": [
+        "0",
+        "0",
+        "\"Zero case\""
+      ],
+      "status": 0
+    },
+    {
+      "assert_name": "assert_equals",
+      "test": "assert_equals tests expected to fail",
+      "args": [
+        "-0",
+        "0",
+        "\"Zero case\""
+      ],
+      "status": 1
+    },
+    {
+      "assert_name": "assert_not_equals",
+      "test": "assert_not_equals tests",
+      "args": [
+        "object \"[object Object]\"",
+        "object \"[object Object]\"",
+        "\"object case\""
+      ],
+      "status": 0
+    },
+    {
+      "assert_name": "assert_not_equals",
+      "test": "assert_not_equals tests",
+      "args": [
+        "-0",
+        "0",
+        "\"Zero case\""
+      ],
+      "status": 0
+    },
+    {
+      "assert_name": "assert_true",
+      "test": "assert_true expected to pass",
+      "args": [
+        "true"
+      ],
+      "status": 0
+    },
+    {
+      "assert_name": "assert_true",
+      "test": "assert_true expected to fail",
+      "args": [
+        "false",
+        "\"false should not be true\""
+      ],
+      "status": 1
+    },
+    {
+      "assert_name": "assert_array_equals",
+      "test": "basic assert_array_equals test",
+      "args": [
+        "[1, NaN]",
+        "[1, NaN]",
+        "\"[1, NaN] is equal to [1, NaN]\""
+      ],
+      "status": 0
+    },
+    {
+      "assert_name": "assert_array_equals",
+      "test": "assert_array_equals with first param undefined",
+      "args": [
+        "undefined",
+        "[1]",
+        "\"undefined equals [1]?\""
+      ],
+      "status": 1
+    },
+    {
+      "assert_name": "assert_array_equals",
+      "test": "assert_array_equals with first param true",
+      "args": [
+        "true",
+        "[1]",
+        "\"true equals [1]?\""
+      ],
+      "status": 1
+    },
+    {
+      "assert_name": "assert_array_equals",
+      "test": "assert_array_equals with first param false",
+      "args": [
+        "false",
+        "[1]",
+        "\"false equals [1]?\""
+      ],
+      "status": 1
+    },
+    {
+      "assert_name": "assert_array_equals",
+      "test": "assert_array_equals with first param null",
+      "args": [
+        "null",
+        "[1]",
+        "\"null equals [1]?\""
+      ],
+      "status": 1
+    },
+    {
+      "assert_name": "assert_array_equals",
+      "test": "assert_array_equals with first param 1",
+      "args": [
+        "1",
+        "[1]",
+        "\"1 equals [1]?\""
+      ],
+      "status": 1
+    },
+    {
+      "assert_name": "assert_array_approx_equals",
+      "test": "basic assert_array_approx_equals test",
+      "args": [
+        "[10, 11]",
+        "[11, 10]",
+        "1",
+        "\"[10, 11] is approximately (+/- 1) [11, 10]\""
+      ],
+      "status": 0
+    },
+    {
+      "assert_name": "assert_approx_equals",
+      "test": "basic assert_approx_equals test",
+      "args": [
+        "10",
+        "11",
+        "1",
+        "\"10 is approximately (+/- 1) 11\""
+      ],
+      "status": 0
+    },
+    {
+      "assert_name": "assert_approx_equals",
+      "test": "basic assert_less_than test",
+      "args": [
+        "10",
+        "11",
+        "1",
+        "\"10 is approximately (+/- 1) 11\""
+      ],
+      "status": 0
+    },
+    {
+      "assert_name": "assert_greater_than",
+      "test": "assert_greater_than expected to fail",
+      "args": [
+        "10",
+        "11",
+        "\"10 is not greater than 11\""
+      ],
+      "status": 1
+    },
+    {
+      "assert_name": "assert_greater_than_equal",
+      "test": "basic assert_greater_than_equal test",
+      "args": [
+        "10",
+        "10",
+        "\"10 is greater than or equal to 10\""
+      ],
+      "status": 0
+    },
+    {
+      "assert_name": "assert_greater_than_equal",
+      "test": "assert_less_than_equal expected to fail",
+      "args": [
+        "\"10\"",
+        "10",
+        "\"'10' is not a number\""
+      ],
+      "status": 1
+    },
+    {
+      "assert_name": "assert_own_property",
+      "test": "test for assert[_not]_own_property and insert_inherits",
+      "args": [
+        "object \"[object Object]\"",
+        "\"a\""
+      ],
+      "status": 0
+    },
+    {
+      "assert_name": "assert_not_own_property",
+      "test": "test for assert[_not]_own_property and insert_inherits",
+      "args": [
+        "object \"[object Object]\"",
+        "\"b\"",
+        "\"unexpected property found: \\\"b\\\"\""
+      ],
+      "status": 0
+    },
+    {
+      "assert_name": "assert_inherits",
+      "test": "test for assert[_not]_own_property and insert_inherits",
+      "args": [
+        "object \"[object Object]\"",
+        "\"b\""
+      ],
+      "status": 0
+    },
+    {
+      "assert_name": "assert_throws_dom",
+      "test": "Test throw DOM exception",
+      "args": [
+        "\"NOT_FOUND_ERR\"",
+        "function \"function () {a.removeChild(b)}\""
+      ],
+      "status": 0
+    },
+    {
+      "assert_name": "assert_throws_js",
+      "test": "Test throw DOMException as JS exception expected to fail",
+      "args": [
+        "function \"function DOMException() {     [native code] }\"",
+        "function \"function () {a.removeChild(b)}\""
+      ],
+      "status": 1
+    },
+    {
+      "assert_name": "assert_throws_js",
+      "test": "Test throw SyntaxError DOMException where JS SyntaxError expected; expected to fail",
+      "args": [
+        "function \"function SyntaxError() {     [native code] }\"",
+        "function \"function () {document.querySelector(\"\")}\""
+      ],
+      "status": 1
+    },
+    {
+      "assert_name": "assert_throws_js",
+      "test": "Test throw JS SyntaxError",
+      "args": [
+        "function \"function SyntaxError() {     [native code] }\"",
+        "function \"function () {JSON.parse(\"{\")}\""
+      ],
+      "status": 0
+    },
+    {
+      "assert_name": "assert_throws_dom",
+      "test": "Test throw DOM SyntaxError",
+      "args": [
+        "\"SyntaxError\"",
+        "function \"function () {document.querySelector(\"\")}\""
+      ],
+      "status": 0
+    },
+    {
+      "assert_name": "assert_throws_dom",
+      "test": "Test throw DOM SyntaxError from subframe",
+      "args": [
+        "\"SyntaxError\"",
+        "function \"function DOMException() {     [native code] }\"",
+        "function \"function () {ifr.contentDocument.querySelector(\"\")}\""
+      ],
+      "status": 0
+    },
+    {
+      "assert_name": "assert_throws_dom",
+      "test": "Test throw DOM SyntaxError from subframe with incorrect global expectation; expected to fail",
+      "args": [
+        "\"SyntaxError\"",
+        "function \"function () {ifr.contentDocument.querySelector(\"\")}\""
+      ],
+      "status": 1
+    },
+    {
+      "assert_name": "assert_throws_dom",
+      "test": "Test throw DOM SyntaxError with incorrect expectation; expected to fail",
+      "args": [
+        "\"SyntaxError\"",
+        "function \"function DOMException() {     [native code] }\"",
+        "function \"function () {document.querySelector(\"\")}\""
+      ],
+      "status": 1
+    },
+    {
+      "assert_name": "assert_throws_dom",
+      "test": "Test throw JS SyntaxError where SyntaxError DOMException expected; expected to fail",
+      "args": [
+        "\"SyntaxError\"",
+        "function \"function () {JSON.parse(\"{\")}\""
+      ],
+      "status": 1
+    },
+    {
+      "assert_name": "assert_throws_dom",
+      "test": "Test throw DOM exception expected to fail",
+      "args": [
+        "\"NOT_FOUND_ERR\"",
+        "function \"function () {a.appendChild(b)}\""
+      ],
+      "status": 1
+    },
+    {
+      "assert_name": "assert_throws_dom",
+      "test": "Test assert_throws_dom with ambiguous DOM-exception expected to Fail",
+      "args": [
+        "0",
+        "function \"function() {throw e}\""
+      ],
+      "status": 1
+    },
+    {
+      "assert_name": "assert_throws_dom",
+      "test": "Test assert_throws_dom with non-DOM-exception expected to Fail",
+      "args": [
+        "\"TEST_ERR\"",
+        "function \"function() {throw e}\""
+      ],
+      "status": 1
+    },
+    {
+      "assert_name": "assert_throws_dom",
+      "test": "Test assert_throws_dom with number code value expected to Pass",
+      "args": [
+        "12",
+        "function \"function() {throw e}\""
+      ],
+      "status": 0
+    },
+    {
+      "assert_name": "assert_throws_dom",
+      "test": "Test assert_throws_dom with number code value and real DOMException expected to Pass",
+      "args": [
+        "12",
+        "function \"function() {throw e}\""
+      ],
+      "status": 0
+    },
+    {
+      "assert_name": "assert_equals",
+      "test": "Test that defines a global and cleans it up",
+      "args": [
+        "1",
+        "1"
+      ],
+      "status": 0
+    },
+    {
+      "assert_name": "assert_equals",
+      "test": "Test that cleanup handlers from previous test ran",
+      "args": [
+        "undefined",
+        "undefined"
+      ],
+      "status": 0
+    },
+    {
+      "assert_name": "assert_true",
+      "test": "Test step_func",
+      "args": [
+        "true"
+      ],
+      "status": 0
+    },
+    {
+      "assert_name": "assert_true",
+      "test": "Test async test with callback",
+      "args": [
+        "true"
+      ],
+      "status": 0
+    },
+    {
+      "assert_name": "assert_true",
+      "test": "Test async test with callback and `this` obj.",
+      "args": [
+        "true"
+      ],
+      "status": 0
+    }
+  ],
+  "type": "complete"
+}
+</script>
+</body>
+</html>
diff --git a/test/wpt/tests/resources/test/tests/functional/api-tests-2.html b/test/wpt/tests/resources/test/tests/functional/api-tests-2.html
new file mode 100644
index 0000000..9af94f6
--- /dev/null
+++ b/test/wpt/tests/resources/test/tests/functional/api-tests-2.html
@@ -0,0 +1,62 @@
+<!DOCTYPE HTML>
+<html>
+<head>
+<title>Sample HTML5 API Tests</title>
+</head>
+<body>
+<h1>Sample HTML5 API Tests</h1>
+<p>There should be two results</p>
+<div id="log"></div>
+<script src="/resources/testharness.js"></script>
+<script src="/resources/testharnessreport.js"></script>
+<script>
+setup({explicit_done:true})
+test(function() {assert_true(true)}, "Test defined before onload");
+
+onload = function() {test(function (){assert_true(true)}, "Test defined after onload");
+done();
+}
+</script>
+<script type="text/json" id="expected">
+{
+  "summarized_status": {
+    "status_string": "OK",
+    "message": null
+  },
+  "summarized_tests": [
+    {
+      "status_string": "PASS",
+      "name": "Test defined after onload",
+      "properties": {},
+      "message": null
+    },
+    {
+      "status_string": "PASS",
+      "name": "Test defined before onload",
+      "properties": {},
+      "message": null
+    }
+  ],
+  "summarized_asserts": [
+    {
+      "assert_name": "assert_true",
+      "test": "Test defined before onload",
+      "args": [
+        "true"
+      ],
+      "status": 0
+    },
+    {
+      "assert_name": "assert_true",
+      "test": "Test defined after onload",
+      "args": [
+        "true"
+      ],
+      "status": 0
+    }
+  ],
+  "type": "complete"
+}
+</script>
+</body>
+</html>
diff --git a/test/wpt/tests/resources/test/tests/functional/api-tests-3.html b/test/wpt/tests/resources/test/tests/functional/api-tests-3.html
new file mode 100644
index 0000000..991fc6d
--- /dev/null
+++ b/test/wpt/tests/resources/test/tests/functional/api-tests-3.html
@@ -0,0 +1,34 @@
+<!DOCTYPE HTML>
+<html>
+<head>
+<title>Sample HTML5 API Tests</title>
+</head>
+<script src="/resources/testharness.js"></script>
+
+<body>
+<h1>Sample HTML5 API Tests</h1>
+<div id="log"></div>
+<script>
+setup({explicit_timeout:true});
+var t = async_test("This test should give a status of 'Not Run' without a delay");
+timeout();
+</script>
+<script type="text/json" id="expected">
+{
+  "summarized_status": {
+    "status_string": "TIMEOUT",
+    "message": null
+  },
+  "summarized_tests": [
+    {
+      "status_string": "NOTRUN",
+      "name": "This test should give a status of 'Not Run' without a delay",
+      "properties": {},
+      "message": null
+    }
+  ],
+  "type": "complete"
+}
+</script>
+</body>
+</html>
diff --git a/test/wpt/tests/resources/test/tests/functional/assert-array-equals.html b/test/wpt/tests/resources/test/tests/functional/assert-array-equals.html
new file mode 100644
index 0000000..b6460a4
--- /dev/null
+++ b/test/wpt/tests/resources/test/tests/functional/assert-array-equals.html
@@ -0,0 +1,162 @@
+<!DOCTYPE HTML>
+<title>assert_array_equals</title>
+<script src="/resources/testharness.js"></script>
+<script src="/resources/testharnessreport.js"></script>
+<div id="log"></div>
+<script>
+test(() => {
+  assert_array_equals([], []);
+}, "empty and equal");
+test(() => {
+  assert_array_equals([1], [1]);
+}, "non-empty and equal");
+test(() => {
+  assert_array_equals([], [1]);
+}, "length differs");
+test(() => {
+  assert_array_equals([1], [,]);
+}, "property is present");
+test(() => {
+  assert_array_equals([,], [1]);
+}, "property is missing");
+test(() => {
+  assert_array_equals([0,1,2,3,4,5,6,7,8,9,10,11,12,13,14,15,16,17,18,19,20], ["x",1,2,3,4,5,6,7,8,9,10,11,12,13,14,15,16,17,18,19,20]);
+}, "property 0 differs");
+test(() => {
+  assert_array_equals([0,1,2,3,4,5,6,7,8,9,10,11,12,13,14,15,16,17,18,19,20], [0,1,2,3,4,"x",6,7,8,9,10,11,12,13,14,15,16,17,18,19,20]);
+}, "property 5 differs");
+test(() => {
+  assert_array_equals([0,1,2,3,4,5,6,7,8,9,10,11,12,13,14,15,16,17,18,19,20,21], [1,2,3,4,5,6,7,8,9,10,11,12,13,14,15,16,17,18,19,20,21]);
+}, "lengths differ and input array beyond display limit");
+test(() => {
+  assert_array_equals([1,2,3,4,5,6,7,8,9,10,11,12,13,14,15,16,17,18,19,20,21], [0,1,2,3,4,5,6,7,8,9,10,11,12,13,14,15,16,17,18,19,20,21]);
+}, "lengths differ and expected array beyond display limit");
+test(() => {
+  assert_array_equals([0,1,2,3,4,5,6,7,8,9,10,11,12,13,14,15,16,17,18,19,20,21], [,1,2,3,4,5,6,7,8,9,10,11,12,13,14,15,16,17,18,19,20,21]);
+}, "property 0 is present and arrays are beyond display limit");
+test(() => {
+  assert_array_equals([,1,2,3,4,5,6,7,8,9,10,11,12,13,14,15,16,17,18,19,20,21], [0,1,2,3,4,5,6,7,8,9,10,11,12,13,14,15,16,17,18,19,20,21]);
+}, "property 0 is missing and arrays are beyond display limit");
+test(() => {
+  assert_array_equals([0,1,2,3,4,5,6,7,8,9,10,11,12,13,14,15,16,17,18,19,20,21], [0,1,2,3,4,5,6,7,8,9,10,11,12,13,14,15,16,17,,19,20,21]);
+}, "property 18 is present and arrays are beyond display limit");
+test(() => {
+  assert_array_equals([0,1,2,3,4,5,6,7,8,9,10,11,12,13,14,15,16,17,,19,20,21], [0,1,2,3,4,5,6,7,8,9,10,11,12,13,14,15,16,17,18,19,20,21]);
+}, "property 18 is missing and arrays are beyond display limit");
+test(() => {
+  assert_array_equals([0,1,2,3,4,5,6,7,8,9,10,11,12,13,14,15,16,17,18,19,20,21], ["x",1,2,3,4,5,6,7,8,9,10,11,12,13,14,15,16,17,18,19,20,21]);
+}, "property 0 differs and arrays are beyond display limit");
+test(() => {
+  assert_array_equals([0,1,2,3,4,5,6,7,8,9,10,11,12,13,14,15,16,17,18,19,20,21], [0,1,2,3,4,"x",6,7,8,9,10,11,12,13,14,15,16,17,18,19,20,21]);
+}, "property 5 differs and arrays are beyond display limit");
+test(() => {
+  assert_array_equals([0,1,2,3,4,5,6,7,8,9,10,11,12,13,14,15,16,17,18,19,20,21,22,23,24,25,26], [0,1,2,3,4,5,6,7,8,9,10,11,"x",13,14,15,16,17,18,19,20,21,22,23,24,25,26]);
+}, "property 5 differs and arrays are beyond display limit on both sides");
+</script>
+<script type="text/json" id="expected">
+{
+  "type": "complete",
+  "summarized_status": {
+    "message": null,
+    "status_string": "OK"
+  },
+  "summarized_tests": [
+    {
+      "name": "empty and equal",
+      "message": null,
+      "properties": {},
+      "status_string": "PASS"
+    },
+    {
+      "name": "length differs",
+      "message": "assert_array_equals: lengths differ, expected array [1] length 1, got [] length 0",
+      "properties": {},
+      "status_string": "FAIL"
+    },
+    {
+      "name": "lengths differ and expected array beyond display limit",
+      "message": "assert_array_equals: lengths differ, expected array [\u2026, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21] length 22, got [1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21] length 21",
+      "properties": {},
+      "status_string": "FAIL"
+    },
+    {
+      "name": "lengths differ and input array beyond display limit",
+      "message": "assert_array_equals: lengths differ, expected array [1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21] length 21, got [\u2026, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21] length 22",
+      "properties": {},
+      "status_string": "FAIL"
+    },
+    {
+      "name": "non-empty and equal",
+      "message": null,
+      "properties": {},
+      "status_string": "PASS"
+    },
+    {
+      "name": "property 0 differs",
+      "message": "assert_array_equals: expected property 0 to be \"x\" but got 0 (expected array [\"x\", 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20] got [0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20])",
+      "properties": {},
+      "status_string": "FAIL"
+    },
+    {
+      "name": "property 0 differs and arrays are beyond display limit",
+      "message": "assert_array_equals: expected property 0 to be \"x\" but got 0 (expected array [\"x\", 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, \u2026] got [0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, \u2026])",
+      "properties": {},
+      "status_string": "FAIL"
+    },
+    {
+      "name": "property 0 is missing and arrays are beyond display limit",
+      "message": "assert_array_equals: expected property 0 to be \"present\" but was \"missing\" (expected array [0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, \u2026] got [, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, \u2026])",
+      "properties": {},
+      "status_string": "FAIL"
+    },
+    {
+      "name": "property 0 is present and arrays are beyond display limit",
+      "message": "assert_array_equals: expected property 0 to be \"missing\" but was \"present\" (expected array [, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, \u2026] got [0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, \u2026])",
+      "properties": {},
+      "status_string": "FAIL"
+    },
+    {
+      "name": "property 18 is missing and arrays are beyond display limit",
+      "message": "assert_array_equals: expected property 18 to be \"present\" but was \"missing\" (expected array [\u2026, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21] got [\u2026, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, , 19, 20, 21])",
+      "properties": {},
+      "status_string": "FAIL"
+    },
+    {
+      "name": "property 18 is present and arrays are beyond display limit",
+      "message": "assert_array_equals: expected property 18 to be \"missing\" but was \"present\" (expected array [\u2026, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, , 19, 20, 21] got [\u2026, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21])",
+      "properties": {},
+      "status_string": "FAIL"
+    },
+    {
+      "name": "property 5 differs",
+      "message": "assert_array_equals: expected property 5 to be \"x\" but got 5 (expected array [0, 1, 2, 3, 4, \"x\", 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20] got [0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20])",
+      "properties": {},
+      "status_string": "FAIL"
+    },
+    {
+      "name": "property 5 differs and arrays are beyond display limit",
+      "message": "assert_array_equals: expected property 5 to be \"x\" but got 5 (expected array [0, 1, 2, 3, 4, \"x\", 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, \u2026] got [0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, \u2026])",
+      "properties": {},
+      "status_string": "FAIL"
+    },
+    {
+      "name": "property 5 differs and arrays are beyond display limit on both sides",
+      "message": "assert_array_equals: expected property 12 to be \"x\" but got 12 (expected array [\u2026, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, \"x\", 13, 14, 15, 16, 17, 18, 19, 20, 21, \u2026] got [\u2026, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, \u2026])",
+      "properties": {},
+      "status_string": "FAIL"
+    },
+    {
+      "name": "property is missing",
+      "message": "assert_array_equals: expected property 0 to be \"present\" but was \"missing\" (expected array [1] got [])",
+      "properties": {},
+      "status_string": "FAIL"
+    },
+    {
+      "name": "property is present",
+      "message": "assert_array_equals: expected property 0 to be \"missing\" but was \"present\" (expected array [] got [1])",
+      "properties": {},
+      "status_string": "FAIL"
+    }
+  ]
+}
+</script>
diff --git a/test/wpt/tests/resources/test/tests/functional/assert-throws-dom.html b/test/wpt/tests/resources/test/tests/functional/assert-throws-dom.html
new file mode 100644
index 0000000..4dd66b2
--- /dev/null
+++ b/test/wpt/tests/resources/test/tests/functional/assert-throws-dom.html
@@ -0,0 +1,55 @@
+<!DOCTYPE HTML>
+<title>assert_throws_dom</title>
+<script src="/resources/testharness.js"></script>
+<script src="/resources/testharnessreport.js"></script>
+<div id="log"></div>
+<script>
+test(() => {
+  function f() {
+      assert_true(false, "Trivial assertion.");
+
+      // Would lead to throwing a SyntaxError.
+      document.createElement("div").contentEditable = "invalid";
+    }
+
+  assert_throws_dom("SyntaxError", () => { f(); });
+}, "Violated assertion nested in `assert_throws_dom`.");
+</script>
+<script type="text/json" id="expected">
+{
+  "type": "complete",
+  "summarized_status": {
+    "message": null,
+    "status_string": "OK"
+  },
+  "summarized_tests": [
+    {
+      "message": "assert_true: Trivial assertion. expected true got false",
+      "name": "Violated assertion nested in `assert_throws_dom`.",
+      "properties": {},
+      "status_string": "FAIL"
+    }
+  ],
+  "summarized_asserts": [
+    {
+      "assert_name": "assert_throws_dom",
+      "test": "Violated assertion nested in `assert_throws_dom`.",
+      "args": [
+        "\"SyntaxError\"",
+        "function \"() => { f(); }\""
+      ],
+      "status": 1
+    },
+    {
+      "assert_name": "assert_true",
+      "test": "Violated assertion nested in `assert_throws_dom`.",
+      "args": [
+        "false",
+        "\"Trivial assertion.\""
+      ],
+      "status": 1
+    }
+  ]
+}
+</script>
+
diff --git a/test/wpt/tests/resources/test/tests/functional/force_timeout.html b/test/wpt/tests/resources/test/tests/functional/force_timeout.html
new file mode 100644
index 0000000..2058fdb
--- /dev/null
+++ b/test/wpt/tests/resources/test/tests/functional/force_timeout.html
@@ -0,0 +1,60 @@
+<!DOCTYPE HTML>
+<html>
+<head>
+<title>Test#force_timeout</title>
+</head>
+<body>
+<h1>Test#force_timeout</h1>
+<div id="log"></div>
+<script src="/resources/testharness.js"></script>
+<script src="/resources/testharnessreport.js"></script>
+<script>
+setup({ explicit_timeout: true });
+
+test(function(t) {
+    t.force_timeout();
+  }, 'test (synchronous)');
+
+async_test(function(t) {
+    t.step_timeout(function() {
+        t.force_timeout();
+      }, 0);
+  }, 'async_test');
+
+promise_test(function(t) {
+    t.force_timeout();
+
+    return new Promise(function() {});
+  }, 'promise_test');
+</script>
+<script type="text/json" id="expected">
+{
+  "summarized_status": {
+    "status_string": "OK",
+    "message": null
+  },
+  "summarized_tests": [
+    {
+      "status_string": "TIMEOUT",
+      "name": "async_test",
+      "message": "Test timed out",
+      "properties": {}
+    },
+    {
+      "status_string": "TIMEOUT",
+      "name": "promise_test",
+      "message": "Test timed out",
+      "properties": {}
+    },
+    {
+      "status_string": "TIMEOUT",
+      "name": "test (synchronous)",
+      "message": "Test timed out",
+      "properties": {}
+    }
+  ],
+  "type": "complete"
+}
+</script>
+</body>
+</html>
diff --git a/test/wpt/tests/resources/test/tests/functional/generate-callback.html b/test/wpt/tests/resources/test/tests/functional/generate-callback.html
new file mode 100644
index 0000000..11d4174
--- /dev/null
+++ b/test/wpt/tests/resources/test/tests/functional/generate-callback.html
@@ -0,0 +1,153 @@
+<!DOCTYPE HTML>
+<html>
+<head>
+<title>Sample for using generate_tests to create a series of tests that share the same callback.</title>
+<script src="/resources/testharness.js"></script>
+<script src="/resources/testharnessreport.js"></script>
+</head>
+<body>
+<script>
+// generate_tests takes an array of arrays that define tests
+// but lets pass it an empty array and verify it does nothing.
+function null_callback() {
+  throw "null_callback should not be called.";
+}
+generate_tests(null_callback, []);
+
+// Generate 3 tests specifying the name and one parameter
+function validate_arguments(arg1) {
+  assert_equals(arg1, 1, "Ensure that we get our expected argument");
+}
+generate_tests(validate_arguments, [
+  ["first test", 1],
+  ["second test", 1],
+  ["third test", 1],
+]);
+
+// Generate a test passing in a properties object that is shared across tests.
+function validate_properties() {
+  assert_true(this.properties.sentinel, "Ensure that we got the right properties object.");
+}
+generate_tests(validate_properties, [["sentinel check 1"], ["sentinel check 2"]], {sentinel: true});
+
+// Generate a test passing in a properties object that is shared across tests.
+function validate_separate_properties() {
+  if (this.name === "sentinel check 1 unique properties") {
+    assert_true(this.properties.sentinel, "Ensure that we got the right properties object. Expect sentinel: true.");
+  }
+  else {
+    assert_false(this.properties.sentinel, "Ensure that we got the right properties object. Expect sentinel: false.");
+  }
+}
+generate_tests(validate_separate_properties, [["sentinel check 1 unique properties"], ["sentinel check 2 unique properties"]], [{sentinel: true}, {sentinel: false}]);
+
+// Finally generate a complicated set of tests from another data source
+var letters = ["a", "b", "c", "d", "e", "f"];
+var numbers = [0, 1, 2, 3, 4, 5];
+function validate_related_arguments(arg1, arg2) {
+  assert_equals(arg1.charCodeAt(0) - "a".charCodeAt(0), arg2, "Ensure that we can map letters to numbers.");
+}
+function format_as_test(letter, index, letters) {
+  return ["Test to map " + letter + " to " + numbers[index], letter, numbers[index]];
+}
+generate_tests(validate_related_arguments, letters.map(format_as_test));
+</script>
+<script type="text/json" id="expected">
+{
+  "summarized_status": {
+    "status_string": "OK",
+    "message": null
+  },
+  "summarized_tests": [
+    {
+      "status_string": "PASS",
+      "name": "Test to map a to 0",
+      "properties": {},
+      "message": null
+    },
+    {
+      "status_string": "PASS",
+      "name": "Test to map b to 1",
+      "properties": {},
+      "message": null
+    },
+    {
+      "status_string": "PASS",
+      "name": "Test to map c to 2",
+      "properties": {},
+      "message": null
+    },
+    {
+      "status_string": "PASS",
+      "name": "Test to map d to 3",
+      "properties": {},
+      "message": null
+    },
+    {
+      "status_string": "PASS",
+      "name": "Test to map e to 4",
+      "properties": {},
+      "message": null
+    },
+    {
+      "status_string": "PASS",
+      "name": "Test to map f to 5",
+      "properties": {},
+      "message": null
+    },
+    {
+      "status_string": "PASS",
+      "name": "first test",
+      "properties": {},
+      "message": null
+    },
+    {
+      "status_string": "PASS",
+      "name": "second test",
+      "properties": {},
+      "message": null
+    },
+    {
+      "status_string": "PASS",
+      "name": "sentinel check 1",
+      "properties": {
+        "sentinel": true
+      },
+      "message": null
+    },
+    {
+      "status_string": "PASS",
+      "name": "sentinel check 1 unique properties",
+      "properties": {
+        "sentinel": true
+      },
+      "message": null
+    },
+    {
+      "status_string": "PASS",
+      "name": "sentinel check 2",
+      "properties": {
+        "sentinel": true
+      },
+      "message": null
+    },
+    {
+      "status_string": "PASS",
+      "name": "sentinel check 2 unique properties",
+      "properties": {
+        "sentinel": false
+      },
+      "message": null
+    },
+    {
+      "status_string": "PASS",
+      "name": "third test",
+      "properties": {},
+      "message": null
+    }
+  ],
+  "type": "complete"
+}
+</script>
+</body>
+</html>
diff --git a/test/wpt/tests/resources/test/tests/functional/idlharness/IdlDictionary/test_partial_interface_of.html b/test/wpt/tests/resources/test/tests/functional/idlharness/IdlDictionary/test_partial_interface_of.html
new file mode 100644
index 0000000..f635768
--- /dev/null
+++ b/test/wpt/tests/resources/test/tests/functional/idlharness/IdlDictionary/test_partial_interface_of.html
@@ -0,0 +1,89 @@
+<!DOCTYPE HTML>
+<html>
+
+<head>
+  <meta charset="utf-8">
+  <title>idlharness: Partial dictionary</title>
+  <script src="/resources/test/variants.js"></script>
+  <script src="/resources/testharness.js"></script>
+  <script src="/resources/testharnessreport.js"></script>
+  <script src="/resources/WebIDLParser.js"></script>
+  <script src="/resources/idlharness.js"></script>
+</head>
+
+<body>
+  <p>Verify the series of sub-tests that are executed for "partial" dictionary objects.</p>
+  <script>
+    "use strict";
+
+    // No original existence
+    (() => {
+      const idlArray = new IdlArray();
+      idlArray.add_idls('partial dictionary A {};');
+      idlArray.test();
+    })();
+
+    // Multiple partials existence
+    (() => {
+      const idlArray = new IdlArray();
+      idlArray.add_untested_idls('partial dictionary B {};');
+      idlArray.add_idls('partial dictionary B {};');
+      idlArray.add_idls('partial dictionary B {};');
+      idlArray.add_idls('partial dictionary B {};');
+      idlArray.add_idls('dictionary B {};');
+      idlArray.test();
+    })();
+
+    // Original is a namespace, not a dictionary.
+    (() => {
+      const idlArray = new IdlArray();
+      idlArray.add_idls(`
+        partial dictionary C {};
+        namespace C {};`);
+      idlArray.merge_partials();
+    })();
+  </script>
+  <script type="text/json" id="expected">
+{
+  "summarized_status": {
+    "status_string": "OK",
+    "message": null
+  },
+  "summarized_tests": [
+    {
+      "name": "Partial dictionary A: original dictionary defined",
+      "status_string": "FAIL",
+      "properties": {},
+      "message": "assert_true: Original dictionary should be defined expected true got false"
+    },
+    {
+      "name": "Partial dictionary B[2]: original dictionary defined",
+      "status_string": "PASS",
+      "properties": {},
+      "message": null
+    },
+    {
+      "name": "Partial dictionary B[3]: original dictionary defined",
+      "status_string": "PASS",
+      "properties": {},
+      "message": null
+    },
+    {
+      "name": "Partial dictionary B[4]: original dictionary defined",
+      "status_string": "PASS",
+      "properties": {},
+      "message": null
+    },
+    {
+      "name": "Partial dictionary C: original dictionary defined",
+      "status_string": "FAIL",
+      "properties": {},
+      "message": "assert_true: Original C definition should have type dictionary expected true got false"
+    }
+  ],
+  "type": "complete"
+}
+</script>
+</body>
+
+</html>
diff --git a/test/wpt/tests/resources/test/tests/functional/idlharness/IdlInterface/test_exposed_wildcard.html b/test/wpt/tests/resources/test/tests/functional/idlharness/IdlInterface/test_exposed_wildcard.html
new file mode 100644
index 0000000..addc0eb
--- /dev/null
+++ b/test/wpt/tests/resources/test/tests/functional/idlharness/IdlInterface/test_exposed_wildcard.html
@@ -0,0 +1,233 @@
+<!DOCTYPE HTML>
+<html>
+<head>
+  <meta charset="utf-8">
+  <title>idlharness: Exposed=*</title>
+  <script src="/resources/testharness.js"></script>
+  <script src="/resources/testharnessreport.js"></script>
+  <script src="/resources/WebIDLParser.js"></script>
+  <script src="/resources/idlharness.js"></script>
+</head>
+<body>
+<script>
+"use strict";
+
+Object.defineProperty(window, "A", {
+    enumerable: false,
+    writable: true,
+    configurable: true,
+    value: function A() {}
+  });
+Object.defineProperty(window.A, "prototype", {
+    writable: false,
+    value: window.A.prototype
+  });
+A.prototype[Symbol.toStringTag] = "A";
+
+Object.defineProperty(window, "C", {
+    enumerable: false,
+    writable: true,
+    configurable: true,
+    value: function C() {}
+  });
+Object.defineProperty(window.C, "prototype", {
+    writable: false,
+    value: window.C.prototype
+  });
+C.prototype[Symbol.toStringTag] = "C";
+
+Object.defineProperty(window, "D", {
+    enumerable: false,
+    writable: true,
+    configurable: true,
+    value: function D() {}
+  });
+Object.defineProperty(window.D, "prototype", {
+    writable: false,
+    value: window.D.prototype
+  });
+C.prototype[Symbol.toStringTag] = "D";
+Object.defineProperty(window, "B", {
+    enumerable: false,
+    writable: true,
+    configurable: true,
+    value: window.A
+  });
+
+var idlArray = new IdlArray();
+idlArray.add_idls(`
+[Exposed=*, LegacyWindowAlias=B] interface A {};
+[Exposed=*] partial interface A {};
+[Exposed=Window] interface C {};
+[Exposed=*] partial interface C {};
+[Exposed=*] interface D {};
+[Exposed=Window] partial interface D {};
+`);
+idlArray.add_objects({
+  Window: ["window"]
+});
+idlArray.test();
+</script>
+<script type="text/json" id="expected">
+{
+    "summarized_status": {
+        "message": null,
+        "status_string": "OK"
+    },
+    "summarized_tests": [
+        {
+            "name": "A interface object length",
+            "properties": {},
+            "message": null,
+            "status_string": "PASS"
+        },
+        {
+            "name": "A interface object name",
+            "properties": {},
+            "message": null,
+            "status_string": "PASS"
+        },
+        {
+            "name": "A interface: existence and properties of interface object",
+            "properties": {},
+            "message": "assert_throws_js: interface object didn't throw TypeError when called as a function function \"function() {\n            interface_object();\n        }\" did not throw",
+            "status_string": "FAIL"
+        },
+        {
+            "name": "A interface: existence and properties of interface prototype object",
+            "properties": {},
+            "message": null,
+            "status_string": "PASS"
+        },
+        {
+            "name": "A interface: existence and properties of interface prototype object's \"constructor\" property",
+            "properties": {},
+            "message": null,
+            "status_string": "PASS"
+        },
+        {
+            "name": "A interface: existence and properties of interface prototype object's @@unscopables property",
+            "properties": {},
+            "message": null,
+            "status_string": "PASS"
+        },
+        {
+            "name": "A interface: legacy window alias",
+            "properties": {},
+            "message": null,
+            "status_string": "PASS"
+        },
+        {
+            "name": "C interface object length",
+            "properties": {},
+            "message": null,
+            "status_string": "PASS"
+        },
+        {
+            "name": "C interface object name",
+            "properties": {},
+            "message": null,
+            "status_string": "PASS"
+        },
+        {
+            "name": "C interface: existence and properties of interface object",
+            "properties": {},
+            "message": "assert_throws_js: interface object didn't throw TypeError when called as a function function \"function() {\n            interface_object();\n        }\" did not throw",
+            "status_string": "FAIL"
+        },
+        {
+            "name": "C interface: existence and properties of interface prototype object",
+            "properties": {},
+            "message": null,
+            "status_string": "PASS"
+        },
+        {
+            "name": "C interface: existence and properties of interface prototype object's \"constructor\" property",
+            "properties": {},
+            "message": null,
+            "status_string": "PASS"
+        },
+        {
+            "name": "C interface: existence and properties of interface prototype object's @@unscopables property",
+            "properties": {},
+            "message": null,
+            "status_string": "PASS"
+        },
+        {
+            "name": "D interface object length",
+            "properties": {},
+            "message": null,
+            "status_string": "PASS"
+        },
+        {
+            "name": "D interface object name",
+            "properties": {},
+            "message": null,
+            "status_string": "PASS"
+        },
+        {
+            "name": "D interface: existence and properties of interface object",
+            "properties": {},
+            "message": "assert_throws_js: interface object didn't throw TypeError when called as a function function \"function() {\n            interface_object();\n        }\" did not throw",
+            "status_string": "FAIL"
+        },
+        {
+            "name": "D interface: existence and properties of interface prototype object",
+            "properties": {},
+            "message": null,
+            "status_string": "PASS"
+        },
+        {
+            "name": "D interface: existence and properties of interface prototype object's \"constructor\" property",
+            "properties": {},
+            "message": null,
+            "status_string": "PASS"
+        },
+        {
+            "name": "D interface: existence and properties of interface prototype object's @@unscopables property",
+            "properties": {},
+            "message": null,
+            "status_string": "PASS"
+        },
+        {
+            "name": "Partial interface A: original interface defined",
+            "properties": {},
+            "message": null,
+            "status_string": "PASS"
+        },
+        {
+            "name": "Partial interface A: valid exposure set",
+            "properties": {},
+            "message": null,
+            "status_string": "PASS"
+        },
+        {
+            "name": "Partial interface C: original interface defined",
+            "properties": {},
+            "message": null,
+            "status_string": "PASS"
+        },
+        {
+            "name": "Partial interface C: valid exposure set",
+            "properties": {},
+            "message": "Partial C interface is exposed everywhere, the original interface is not.",
+            "status_string": "FAIL"
+        },
+        {
+            "name": "Partial interface D: original interface defined",
+            "properties": {},
+            "message": null,
+            "status_string": "PASS"
+        },
+        {
+            "name": "Partial interface D: valid exposure set",
+            "properties": {},
+            "message": null,
+            "status_string": "PASS"
+        }
+    ],
+    "type": "complete"
+}
+</script>
+</body>
+</html>
diff --git a/test/wpt/tests/resources/test/tests/functional/idlharness/IdlInterface/test_immutable_prototype.html b/test/wpt/tests/resources/test/tests/functional/idlharness/IdlInterface/test_immutable_prototype.html
new file mode 100644
index 0000000..5fe0591
--- /dev/null
+++ b/test/wpt/tests/resources/test/tests/functional/idlharness/IdlInterface/test_immutable_prototype.html
@@ -0,0 +1,298 @@
+<!DOCTYPE HTML>
+<html>
+<head>
+  <meta charset="utf-8">
+  <title>idlharness: Immutable prototypes</title>
+  <script src="/resources/testharness.js"></script>
+  <script src="/resources/testharnessreport.js"></script>
+  <script src="/resources/WebIDLParser.js"></script>
+  <script src="/resources/idlharness.js"></script>
+</head>
+<body>
+<script>
+"use strict";
+
+Object.defineProperty(window, "Foo", {
+    enumerable: false,
+    writable: true,
+    configurable: true,
+    value: function Foo() {
+        if (!new.target) {
+            throw new TypeError('Foo() must be called with new');
+        }
+    }
+  });
+Object.defineProperty(window.Foo, "prototype", {
+    writable: false,
+    value: window.Foo.prototype
+  });
+Foo.prototype[Symbol.toStringTag] = "Foo";
+
+var idlArray = new IdlArray();
+idlArray.add_untested_idls("interface EventTarget {};");
+idlArray.add_idls(
+    "[Global=Window, Exposed=Window]\n" +
+    "interface Window : EventTarget {};\n" +
+
+    "[Global=Window, Exposed=Window]\n" +
+    "interface Foo { constructor(); };"
+  );
+idlArray.add_objects({
+  Foo: ["new Foo()"],
+  Window: ["window"]
+});
+idlArray.test();
+</script>
+<script type="text/json" id="expected">
+{
+    "summarized_status": {
+        "message": null,
+        "status_string": "OK"
+    },
+    "summarized_tests": [
+        {
+            "name": "Foo interface object length",
+            "status_string": "PASS",
+            "properties": {},
+            "message": null
+        },
+        {
+            "name": "Foo interface object name",
+            "status_string": "PASS",
+            "properties": {},
+            "message": null
+        },
+        {
+            "name": "Foo interface: existence and properties of interface object",
+            "status_string": "PASS",
+            "properties": {},
+            "message": null
+        },
+        {
+            "name": "Foo interface: existence and properties of interface prototype object",
+            "status_string": "PASS",
+            "properties": {},
+            "message": null
+        },
+        {
+            "name": "Foo interface: existence and properties of interface prototype object's \"constructor\" property",
+            "status_string": "PASS",
+            "properties": {},
+            "message": null
+        },
+        {
+            "name": "Foo interface: existence and properties of interface prototype object's @@unscopables property",
+            "status_string": "PASS",
+            "properties": {},
+            "message": null
+        },
+        {
+            "name": "Foo interface: internal [[SetPrototypeOf]] method of global platform object - setting to a new value via Object.setPrototypeOf should throw a TypeError",
+            "status_string": "FAIL",
+            "properties": {},
+            "message": "assert_throws_js: function \"function() {\n            Object.setPrototypeOf(obj, newValue);\n        }\" did not throw"
+        },
+        {
+            "name": "Foo interface: internal [[SetPrototypeOf]] method of global platform object - setting to a new value via Reflect.setPrototypeOf should return false",
+            "status_string": "FAIL",
+            "properties": {},
+            "message": "assert_false: expected false got true"
+        },
+        {
+            "name": "Foo interface: internal [[SetPrototypeOf]] method of global platform object - setting to a new value via __proto__ should throw a TypeError",
+            "status_string": "FAIL",
+            "properties": {},
+            "message": "assert_throws_js: function \"function() {\n            obj.__proto__ = newValue;\n        }\" did not throw"
+        },
+        {
+            "name": "Foo interface: internal [[SetPrototypeOf]] method of global platform object - setting to its original value via Object.setPrototypeOf should not throw",
+            "status_string": "PASS",
+            "properties": {},
+            "message": null
+        },
+        {
+            "name": "Foo interface: internal [[SetPrototypeOf]] method of global platform object - setting to its original value via Reflect.setPrototypeOf should return true",
+            "status_string": "PASS",
+            "properties": {},
+            "message": null
+        },
+        {
+            "name": "Foo interface: internal [[SetPrototypeOf]] method of global platform object - setting to its original value via __proto__ should not throw",
+            "status_string": "PASS",
+            "properties": {},
+            "message": null
+        },
+        {
+            "name": "Foo interface: internal [[SetPrototypeOf]] method of interface prototype object - setting to a new value via Object.setPrototypeOf should throw a TypeError",
+            "status_string": "FAIL",
+            "properties": {},
+            "message": "assert_throws_js: function \"function() {\n            Object.setPrototypeOf(obj, newValue);\n        }\" did not throw"
+        },
+        {
+            "name": "Foo interface: internal [[SetPrototypeOf]] method of interface prototype object - setting to a new value via Reflect.setPrototypeOf should return false",
+            "status_string": "FAIL",
+            "properties": {},
+            "message": "assert_false: expected false got true"
+        },
+        {
+            "name": "Foo interface: internal [[SetPrototypeOf]] method of interface prototype object - setting to a new value via __proto__ should throw a TypeError",
+            "status_string": "FAIL",
+            "properties": {},
+            "message": "assert_throws_js: function \"function() {\n            obj.__proto__ = newValue;\n        }\" did not throw"
+        },
+        {
+            "name": "Foo interface: internal [[SetPrototypeOf]] method of interface prototype object - setting to its original value via Object.setPrototypeOf should not throw",
+            "status_string": "PASS",
+            "properties": {},
+            "message": null
+        },
+        {
+            "name": "Foo interface: internal [[SetPrototypeOf]] method of interface prototype object - setting to its original value via Reflect.setPrototypeOf should return true",
+            "status_string": "PASS",
+            "properties": {},
+            "message": null
+        },
+        {
+            "name": "Foo interface: internal [[SetPrototypeOf]] method of interface prototype object - setting to its original value via __proto__ should not throw",
+            "status_string": "PASS",
+            "properties": {},
+            "message": null
+        },
+        {
+            "name": "Foo must be primary interface of new Foo()",
+            "status_string": "PASS",
+            "properties": {},
+            "message": null
+        },
+        {
+            "name": "Stringification of new Foo()",
+            "status_string": "PASS",
+            "properties": {},
+            "message": null
+        },
+        {
+            "name": "Stringification of window",
+            "status_string": "PASS",
+            "properties": {},
+            "message": null
+        },
+        {
+            "name": "Window interface object length",
+            "status_string": "PASS",
+            "properties": {},
+            "message": null
+        },
+        {
+            "name": "Window interface object name",
+            "status_string": "PASS",
+            "properties": {},
+            "message": null
+        },
+        {
+            "name": "Window interface: existence and properties of interface object",
+            "status_string": "PASS",
+            "properties": {},
+            "message": null
+        },
+        {
+            "name": "Window interface: existence and properties of interface prototype object",
+            "status_string": "PASS",
+            "properties": {},
+            "message": null
+        },
+        {
+            "name": "Window interface: existence and properties of interface prototype object's \"constructor\" property",
+            "status_string": "PASS",
+            "properties": {},
+            "message": null
+        },
+        {
+            "name": "Window interface: existence and properties of interface prototype object's @@unscopables property",
+            "status_string": "PASS",
+            "properties": {},
+            "message": null
+        },
+        {
+            "name": "Window interface: internal [[SetPrototypeOf]] method of global platform object - setting to a new value via Object.setPrototypeOf should throw a TypeError",
+            "status_string": "PASS",
+            "properties": {},
+            "message": null
+        },
+        {
+            "name": "Window interface: internal [[SetPrototypeOf]] method of global platform object - setting to a new value via Reflect.setPrototypeOf should return false",
+            "status_string": "PASS",
+            "properties": {},
+            "message": null
+        },
+        {
+            "name": "Window interface: internal [[SetPrototypeOf]] method of global platform object - setting to a new value via __proto__ should throw a TypeError",
+            "status_string": "PASS",
+            "properties": {},
+            "message": null
+        },
+        {
+            "name": "Window interface: internal [[SetPrototypeOf]] method of global platform object - setting to its original value via Object.setPrototypeOf should not throw",
+            "status_string": "PASS",
+            "properties": {},
+            "message": null
+        },
+        {
+            "name": "Window interface: internal [[SetPrototypeOf]] method of global platform object - setting to its original value via Reflect.setPrototypeOf should return true",
+            "status_string": "PASS",
+            "properties": {},
+            "message": null
+        },
+        {
+            "name": "Window interface: internal [[SetPrototypeOf]] method of global platform object - setting to its original value via __proto__ should not throw",
+            "status_string": "PASS",
+            "properties": {},
+            "message": null
+        },
+        {
+            "name": "Window interface: internal [[SetPrototypeOf]] method of interface prototype object - setting to a new value via Object.setPrototypeOf should throw a TypeError",
+            "status_string": "PASS",
+            "properties": {},
+            "message": null
+        },
+        {
+            "name": "Window interface: internal [[SetPrototypeOf]] method of interface prototype object - setting to a new value via Reflect.setPrototypeOf should return false",
+            "status_string": "PASS",
+            "properties": {},
+            "message": null
+        },
+        {
+            "name": "Window interface: internal [[SetPrototypeOf]] method of interface prototype object - setting to a new value via __proto__ should throw a TypeError",
+            "status_string": "PASS",
+            "properties": {},
+            "message": null
+        },
+        {
+            "name": "Window interface: internal [[SetPrototypeOf]] method of interface prototype object - setting to its original value via Object.setPrototypeOf should not throw",
+            "status_string": "PASS",
+            "properties": {},
+            "message": null
+        },
+        {
+            "name": "Window interface: internal [[SetPrototypeOf]] method of interface prototype object - setting to its original value via Reflect.setPrototypeOf should return true",
+            "status_string": "PASS",
+            "properties": {},
+            "message": null
+        },
+        {
+            "name": "Window interface: internal [[SetPrototypeOf]] method of interface prototype object - setting to its original value via __proto__ should not throw",
+            "status_string": "PASS",
+            "properties": {},
+            "message": null
+        },
+        {
+            "name": "Window must be primary interface of window",
+            "status_string": "PASS",
+            "properties": {},
+            "message": null
+        }
+    ],
+    "type": "complete"
+}
+</script>
+</body>
+</html>
diff --git a/test/wpt/tests/resources/test/tests/functional/idlharness/IdlInterface/test_interface_mixin.html b/test/wpt/tests/resources/test/tests/functional/idlharness/IdlInterface/test_interface_mixin.html
new file mode 100644
index 0000000..be2844e
--- /dev/null
+++ b/test/wpt/tests/resources/test/tests/functional/idlharness/IdlInterface/test_interface_mixin.html
@@ -0,0 +1,131 @@
+<!DOCTYPE HTML>
+<html>
+
+<head>
+  <meta charset="utf-8">
+  <title>idlharness: interface mixins</title>
+  <script src="/resources/testharness.js"></script>
+  <script src="/resources/testharnessreport.js"></script>
+  <script src="/resources/WebIDLParser.js"></script>
+  <script src="/resources/idlharness.js"></script>
+</head>
+
+<body>
+  <p>Verify the series of sub-tests that are executed for "interface mixin" objects.</p>
+  <script>
+    "use strict";
+
+    // Simple includes statement (valid)
+    (() => {
+      const idlArray = new IdlArray();
+      idlArray.add_idls(`
+        [Exposed=Window] interface I1 {};
+        interface mixin M1 { attribute any a1; };
+        I1 includes M1;`);
+      idlArray.merge_partials();
+      idlArray.merge_mixins();
+    })();
+
+    // Partial interface mixin (valid)
+    (() => {
+      const idlArray = new IdlArray();
+      idlArray.add_idls(`
+        [Exposed=Window] interface I2 {};
+        interface mixin M2 {};
+        partial interface mixin M2 { attribute any a2; };
+        I2 includes M2;`);
+      idlArray.merge_partials();
+      idlArray.merge_mixins();
+    })();
+
+    // Partial interface mixin without original mixin
+    (() => {
+      const idlArray = new IdlArray();
+      idlArray.add_idls('partial interface mixin M3 {};');
+      idlArray.merge_partials();
+      idlArray.merge_mixins();
+    })();
+
+    // Name clash between mixin and partial mixin
+    (() => {
+      const idlArray = new IdlArray();
+      idlArray.add_idls(`
+        interface mixin M4 { attribute any a4; };
+        partial interface mixin M4 { attribute any a4; };`);
+      idlArray.merge_partials();
+      idlArray.merge_mixins();
+    })();
+
+    // Name clash between interface and mixin
+    (() => {
+      const idlArray = new IdlArray();
+      idlArray.add_untested_idls(`
+        interface mixin M5 { attribute any a5; };
+        interface I5 { attribute any a5; };
+        I5 includes M5;`);
+      idlArray.merge_partials();
+      idlArray.merge_mixins();
+    })();
+  </script>
+  <script type="text/json" id="expected">
+{
+  "summarized_status": {
+    "status_string": "OK",
+    "message": null
+  },
+  "summarized_tests": [
+    {
+      "name": "I1 includes M1: member names are unique",
+      "status_string": "PASS",
+      "properties": {},
+      "message": null
+    },
+    {
+      "name": "I2 includes M2: member names are unique",
+      "status_string": "PASS",
+      "properties": {},
+      "message": null
+    },
+    {
+      "name": "I5 includes M5: member names are unique",
+      "status_string": "FAIL",
+      "properties": {},
+      "message": "assert_true: member a5 is unique expected true got false"
+    },
+    {
+      "name": "Partial interface mixin M2: member names are unique",
+      "status_string": "PASS",
+      "properties": {},
+      "message": null
+    },
+    {
+      "name": "Partial interface mixin M2: original interface mixin defined",
+      "status_string": "PASS",
+      "properties": {},
+      "message": null
+    },
+    {
+      "name": "Partial interface mixin M3: original interface mixin defined",
+      "status_string": "FAIL",
+      "properties": {},
+      "message": "assert_true: Original interface mixin should be defined expected true got false"
+    },
+    {
+      "name": "Partial interface mixin M4: member names are unique",
+      "status_string": "FAIL",
+      "properties": {},
+      "message": "assert_true: member a4 is unique expected true got false"
+    },
+    {
+      "name": "Partial interface mixin M4: original interface mixin defined",
+      "status_string": "PASS",
+      "properties": {},
+      "message": null
+    }
+  ],
+  "type": "complete"
+}
+</script>
+</body>
+
+</html>
diff --git a/test/wpt/tests/resources/test/tests/functional/idlharness/IdlInterface/test_partial_interface_of.html b/test/wpt/tests/resources/test/tests/functional/idlharness/IdlInterface/test_partial_interface_of.html
new file mode 100644
index 0000000..7dd9e67
--- /dev/null
+++ b/test/wpt/tests/resources/test/tests/functional/idlharness/IdlInterface/test_partial_interface_of.html
@@ -0,0 +1,187 @@
+<!DOCTYPE HTML>
+<html>
+
+<head>
+  <meta charset="utf-8">
+  <title>idlharness: Partial interface</title>
+  <script src="/resources/test/variants.js"></script>
+  <script src="/resources/testharness.js"></script>
+  <script src="/resources/testharnessreport.js"></script>
+  <script src="/resources/WebIDLParser.js"></script>
+  <script src="/resources/idlharness.js"></script>
+</head>
+
+<body>
+  <p>Verify the series of sub-tests that are executed for "partial" interface objects.</p>
+  <script>
+    "use strict";
+
+    // No original existence
+    (() => {
+      const idlArray = new IdlArray();
+      idlArray.add_idls('partial interface A {};');
+      idlArray.test();
+    })();
+
+    // Valid exposure (Note: Worker -> {Shared,Dedicated,Service}Worker)
+    (() => {
+      const idlArray = new IdlArray();
+      idlArray.add_untested_idls(`
+        [Exposed=(Worker)]
+        interface B {};
+
+        [Exposed=(DedicatedWorker, ServiceWorker, SharedWorker)]
+        interface C {};`);
+      idlArray.add_idls(`
+        [Exposed=(DedicatedWorker, ServiceWorker, SharedWorker)]
+        partial interface B {};
+
+        [Exposed=(Worker)]
+        partial interface C {};`);
+      idlArray.merge_partials();
+    })();
+
+    // Invalid exposure
+    (() => {
+      const idlArray = new IdlArray();
+      idlArray.add_untested_idls(`
+        [Exposed=(Window, ServiceWorker)]
+        interface D {};`);
+      idlArray.add_idls(`
+        [Exposed=(DedicatedWorker)]
+        partial interface D {};`);
+      idlArray.merge_partials();
+    })();
+
+    // Original is a namespace, not an interface.
+    (() => {
+      const idlArray = new IdlArray();
+      idlArray.add_idls(`
+        partial interface E {};
+        namespace E {};`);
+      idlArray.merge_partials();
+    })();
+
+    (() => {
+      const idlArray = new IdlArray();
+      idlArray.add_idls(`
+        partial interface F {};
+        partial interface mixin G {};
+      `);
+      idlArray.add_dependency_idls(`
+        interface F {};
+        interface mixin G {};
+        interface mixin H {};
+        F includes H;
+        I includes H;
+        J includes G;
+        interface K : J {};
+        interface L : F {};
+      `);
+      test(() => {
+        // Convert idlArray.includes into a Map from name of target interface to
+        // name of included mixin. (This assumes each interface includes at most
+        // one mixin, otherwise later includes would clobber earlier ones.)
+        const includes = new Map(idlArray.includes.map(i => [i.target, i.includes]));
+        // F is tested, so H is a dep.
+        assert_equals(includes.get('F'), 'H', 'F should be picked up');
+        // H is not tested, so I is not a dep.
+        assert_false(includes.has('I'), 'I should be ignored');
+        // G is a dep, so J is a dep.
+        assert_equals(includes.get('J'), 'G', 'J should be picked up');
+        // K isn't a dep because J isn't defined.
+        assert_false('K' in idlArray.members, 'K should be ignored');
+        // L isn't a dep because F is untested.
+        assert_false('L' in idlArray.members, 'L should be ignored');
+      }, 'partial mixin dep implications');
+    })();
+
+    // Name clash (partials)
+    (() => {
+      const idlArray = new IdlArray();
+      idlArray.add_idls(`
+        interface M { attribute any A; };
+        partial interface M { attribute any A; };`);
+      idlArray.merge_partials();
+    })();
+  </script>
+  <script type="text/json" id="expected">
+{
+  "summarized_status": {
+    "status_string": "OK",
+    "message": null
+  },
+  "summarized_tests": [
+    {
+      "name": "Partial interface A: original interface defined",
+      "status_string": "FAIL",
+      "properties": {},
+      "message": "assert_true: Original interface should be defined expected true got false"
+    },
+    {
+      "name": "Partial interface B: original interface defined",
+      "status_string": "PASS",
+      "properties": {},
+      "message": null
+    },
+    {
+      "name": "Partial interface B: valid exposure set",
+      "status_string": "PASS",
+      "properties": {},
+      "message": null
+    },
+    {
+      "name": "Partial interface C: original interface defined",
+      "status_string": "PASS",
+      "properties": {},
+      "message": null
+    },
+    {
+      "name": "Partial interface C: valid exposure set",
+      "status_string": "PASS",
+      "properties": {},
+      "message": null
+    },
+    {
+      "name": "Partial interface D: original interface defined",
+      "status_string": "PASS",
+      "properties": {},
+      "message": null
+    },
+    {
+      "name": "Partial interface D: valid exposure set",
+      "status_string": "FAIL",
+      "properties": {},
+      "message": "Partial D interface is exposed to 'DedicatedWorker', the original interface is not."
+    },
+    {
+      "name": "Partial interface E: original interface defined",
+      "status_string": "FAIL",
+      "properties": {},
+      "message": "assert_true: Original E definition should have type interface expected true got false"
+    },
+    {
+      "name": "partial mixin dep implications",
+      "status_string": "PASS",
+      "properties": {},
+      "message": null
+    },
+    {
+      "name": "Partial interface M: original interface defined",
+      "status_string": "PASS",
+      "properties": {},
+      "message": null
+    },
+    {
+      "name": "Partial interface M: member names are unique",
+      "status_string": "FAIL",
+      "properties": {},
+      "message": "assert_true: member A is unique expected true got false"
+    }
+  ],
+  "type": "complete"
+}
+</script>
+</body>
+
+</html>
diff --git a/test/wpt/tests/resources/test/tests/functional/idlharness/IdlInterface/test_primary_interface_of.html b/test/wpt/tests/resources/test/tests/functional/idlharness/IdlInterface/test_primary_interface_of.html
new file mode 100644
index 0000000..309de60
--- /dev/null
+++ b/test/wpt/tests/resources/test/tests/functional/idlharness/IdlInterface/test_primary_interface_of.html
@@ -0,0 +1,116 @@
+<!DOCTYPE HTML>
+<html>
+<head>
+  <meta charset="utf-8">
+  <title>idlharness: Primary interface</title>
+  <script src="/resources/testharness.js"></script>
+  <script src="/resources/testharnessreport.js"></script>
+  <script src="/resources/WebIDLParser.js"></script>
+  <script src="/resources/idlharness.js"></script>
+</head>
+<body>
+<p>Verify the series of sub-tests that are executed for "tested" interface
+objects but skipped for "untested" interface objects.</p>
+<script>
+"use strict";
+
+function FooParent() {
+    if (!new.target) {
+        throw new TypeError('FooParent() must be called with new');
+    }
+}
+Object.defineProperty(window, "Foo", {
+    enumerable: false,
+    writable: true,
+    configurable: true,
+    value: function Foo() {
+        if (!new.target) {
+            throw new TypeError('Foo() must be called with new');
+        }
+    }
+  });
+Object.defineProperty(window.Foo, "prototype", {
+    writable: false,
+    value: new FooParent()
+  });
+Object.defineProperty(window.Foo.prototype, "constructor", {
+    enumerable: false,
+    writable: true,
+    configurable: true,
+    value: window.Foo
+  });
+Object.setPrototypeOf(Foo, FooParent);
+Foo.prototype[Symbol.toStringTag] = "Foo";
+
+var idlArray = new IdlArray();
+idlArray.add_untested_idls("interface FooParent {};");
+idlArray.add_idls(
+    "interface Foo : FooParent { constructor(); };"
+  );
+idlArray.add_objects({
+  Foo: ["new Foo()"],
+  FooParent: ["new FooParent()"]
+});
+idlArray.test();
+</script>
+<script type="text/json" id="expected">
+{
+  "summarized_status": {
+    "status_string": "OK",
+    "message": null
+  },
+  "summarized_tests": [
+    {
+      "name": "Foo interface object length",
+      "status_string": "PASS",
+      "properties": {},
+      "message": null
+    },
+    {
+      "name": "Foo interface object name",
+      "status_string": "PASS",
+      "properties": {},
+      "message": null
+    },
+    {
+      "name": "Foo interface: existence and properties of interface object",
+      "status_string": "PASS",
+      "properties": {},
+      "message": null
+    },
+    {
+      "name": "Foo interface: existence and properties of interface prototype object",
+      "status_string": "PASS",
+      "properties": {},
+      "message": null
+    },
+    {
+      "name": "Foo interface: existence and properties of interface prototype object's \"constructor\" property",
+      "status_string": "PASS",
+      "properties": {},
+      "message": null
+    },
+    {
+      "name": "Foo interface: existence and properties of interface prototype object's @@unscopables property",
+      "status_string": "PASS",
+      "properties": {},
+      "message": null
+    },
+    {
+      "name": "Foo must be primary interface of new Foo()",
+      "status_string": "PASS",
+      "properties": {},
+      "message": null
+    },
+    {
+      "name": "Stringification of new Foo()",
+      "status_string": "PASS",
+      "properties": {},
+      "message": null
+    }
+  ],
+  "type": "complete"
+}
+</script>
+</body>
+</html>
diff --git a/test/wpt/tests/resources/test/tests/functional/idlharness/IdlInterface/test_to_json_operation.html b/test/wpt/tests/resources/test/tests/functional/idlharness/IdlInterface/test_to_json_operation.html
new file mode 100644
index 0000000..bbc502a
--- /dev/null
+++ b/test/wpt/tests/resources/test/tests/functional/idlharness/IdlInterface/test_to_json_operation.html
@@ -0,0 +1,177 @@
+<!DOCTYPE HTML>
+<html>
+<head>
+  <meta charset="utf-8">
+  <title>IdlInterface.prototype.test_to_json_operation()</title>
+  <script src="/resources/testharness.js"></script>
+  <script src="/resources/testharnessreport.js"></script>
+  <script src="/resources/WebIDLParser.js"></script>
+  <script src="/resources/idlharness.js"></script>
+  <script src="../../../../idl-helper.js"></script>
+</head>
+<body>
+<script>
+    "use strict";
+    function wrap(member, obj) {
+        function F(obj) {
+            this._obj = obj;
+        }
+
+        F.prototype.toJSON = function() {
+            return this._obj;
+        }
+        Object.defineProperty(F, 'name', { value: member.name });
+        return new F(obj);
+    }
+
+    var i, obj;
+    i = interfaceFrom("interface A { [Default] object toJSON(); attribute long foo; };");
+    i.test_to_json_operation("object", wrap(i, { foo: 123 }), i.members[0]);
+
+    // should fail (wrong type)
+    i = interfaceFrom("interface B { [Default] object toJSON(); attribute long foo; };");
+    i.test_to_json_operation("object", wrap(i, { foo: "a value" }), i.members[0]);
+
+    // should handle extraneous attributes (e.g. from an extension specification)
+    i = interfaceFrom("interface C { [Default] object toJSON(); attribute long foo; };");
+    i.test_to_json_operation("object", wrap(i, { foo: 123, bar: 456 }), i.members[0]);
+
+    // should fail (missing property)
+    i = interfaceFrom("interface D { [Default] object toJSON(); attribute long foo; };");
+    i.test_to_json_operation("object", wrap(i, { }), i.members[0]);
+
+    // should fail (should be writable)
+    obj = Object.defineProperties({}, { foo: {
+        writable: false,
+        enumerable: true,
+        configurable: true,
+        value: 123
+    }});
+    i = interfaceFrom("interface F { [Default] object toJSON(); attribute long foo; };");
+    i.test_to_json_operation("object", wrap(i, obj), i.members[0]);
+
+    // should fail (should be enumerable)
+    obj = Object.defineProperties({}, { foo: {
+        writable: true,
+        enumerable: false,
+        configurable: true,
+        value: 123
+    }});
+    i = interfaceFrom("interface G { [Default] object toJSON(); attribute long foo; };");
+    i.test_to_json_operation("object", wrap(i, obj), i.members[0]);
+
+    // should fail (should be configurable)
+    obj = Object.defineProperties({}, { foo: {
+        writable: true,
+        enumerable: true,
+        configurable: false,
+        value: 123
+    }});
+    i = interfaceFrom("interface H { [Default] object toJSON(); attribute long foo; };");
+    i.test_to_json_operation("object", wrap(i, obj), i.members[0]);
+
+    var idl = new IdlArray();
+    idl.add_idls("interface I : J { [Default] object toJSON(); attribute long foo; };");
+    idl.add_idls("interface J { [Default] object toJSON(); attribute DOMString foo;};");
+    var i = idl.members.I;
+    i.test_to_json_operation("object", wrap(i, { foo: 123 }), i.members[0]);
+
+    i = interfaceFrom("interface K { [Default] object toJSON(); };");
+    i.test_to_json_operation("object", wrap(i, {}), i.members[0]);
+
+    i = interfaceFrom("interface L { DOMString toJSON(); };");
+    i.test_to_json_operation("object", wrap(i, "a string"), i.members[0]);
+
+    // should fail (wrong output type)
+    i = interfaceFrom("interface M { DOMString toJSON(); };");
+    i.test_to_json_operation("object", wrap(i, {}), i.members[0]);
+
+    // should fail (not an IDL type)
+    i = interfaceFrom("interface N { DOMException toJSON(); };");
+    i.test_to_json_operation("object", wrap(i, {}), i.members[0]);
+</script>
+<script type="text/json" id="expected">
+    {
+        "summarized_status": {
+            "message": null,
+            "status_string": "OK"
+        },
+        "summarized_tests": [
+            {
+                "message": null,
+                "name": "A interface: default toJSON operation on object",
+                "properties": {},
+                "status_string": "PASS"
+            },
+            {
+                "message": "assert_equals: expected \"number\" but got \"string\"",
+                "name": "B interface: default toJSON operation on object",
+                "properties": {},
+                "status_string": "FAIL"
+            },
+            {
+                "message": null,
+                "name": "C interface: default toJSON operation on object",
+                "properties": {},
+                "status_string": "PASS"
+            },
+            {
+                "message": "assert_true: property \"foo\" should be present in the output of D.prototype.toJSON() expected true got false",
+                "name": "D interface: default toJSON operation on object",
+                "properties": {},
+                "status_string": "FAIL"
+            },
+            {
+                "message": "assert_true: property foo should be writable expected true got false",
+                "name": "F interface: default toJSON operation on object",
+                "properties": {},
+                "status_string": "FAIL"
+            },
+            {
+                "message": "assert_true: property foo should be enumerable expected true got false",
+                "name": "G interface: default toJSON operation on object",
+                "properties": {},
+                "status_string": "FAIL"
+            },
+            {
+                "message": "assert_true: property foo should be configurable expected true got false",
+                "name": "H interface: default toJSON operation on object",
+                "properties": {},
+                "status_string": "FAIL"
+            },
+            {
+                "message": null,
+                "name": "I interface: default toJSON operation on object",
+                "properties": {},
+                "status_string": "PASS"
+            },
+            {
+                "message": null,
+                "name": "K interface: default toJSON operation on object",
+                "properties": {},
+                "status_string": "PASS"
+            },
+            {
+                "message": null,
+                "name": "L interface: toJSON operation on object",
+                "properties": {},
+                "status_string": "PASS"
+            },
+            {
+                "message": "assert_equals: expected \"string\" but got \"object\"",
+                "name": "M interface: toJSON operation on object",
+                "properties": {},
+                "status_string": "FAIL"
+            },
+            {
+                "message": "assert_true: {\"type\":\"return-type\",\"extAttrs\":[],\"generic\":\"\",\"nullable\":false,\"union\":false,\"idlType\":\"DOMException\"} is not an appropriate return value for the toJSON operation of N expected true got false",
+                "name": "N interface: toJSON operation on object",
+                "properties": {},
+                "status_string": "FAIL"
+            }
+        ],
+        "type": "complete"
+    }
+</script>
+</body>
+</html>
diff --git a/test/wpt/tests/resources/test/tests/functional/idlharness/IdlNamespace/test_attribute.html b/test/wpt/tests/resources/test/tests/functional/idlharness/IdlNamespace/test_attribute.html
new file mode 100644
index 0000000..2c94061
--- /dev/null
+++ b/test/wpt/tests/resources/test/tests/functional/idlharness/IdlNamespace/test_attribute.html
@@ -0,0 +1,100 @@
+<!DOCTYPE HTML>
+<html>
+<head>
+  <meta charset="utf-8">
+  <title>idlharness: namespace attribute</title>
+  <script src="/resources/testharness.js"></script>
+  <script src="/resources/testharnessreport.js"></script>
+  <script src="/resources/WebIDLParser.js"></script>
+  <script src="/resources/idlharness.js"></script>
+</head>
+<body>
+<p>Verify the series of sub-tests that are executed for namespace attributes.</p>
+<script>
+"use strict";
+
+Object.defineProperty(self, "foo", {
+  value: {
+    truth: true,
+  },
+  writable: true,
+  enumerable: false,
+  configurable: true,
+});
+
+var idlArray = new IdlArray();
+idlArray.add_idls(`
+[Exposed=Window]
+namespace foo {
+  readonly attribute bool truth;
+  readonly attribute bool lies;
+};`);
+idlArray.test();
+</script>
+<script type="text/json" id="expected">
+{
+  "summarized_status": {
+    "status_string": "OK",
+    "message": null
+  },
+  "summarized_tests": [
+    {
+      "name": "foo namespace: extended attributes",
+      "status_string": "PASS",
+      "properties": {},
+      "message": null
+    },
+    {
+      "name": "foo namespace: property descriptor",
+      "status_string": "PASS",
+      "properties": {},
+      "message": null
+    },
+    {
+      "name": "foo namespace: [[Extensible]] is true",
+      "status_string": "PASS",
+      "properties": {},
+      "message": null
+    },
+    {
+      "name": "foo namespace: [[Prototype]] is Object.prototype",
+      "status_string": "PASS",
+      "properties": {},
+      "message": null
+    },
+    {
+      "name": "foo namespace: typeof is \"object\"",
+      "status_string": "PASS",
+      "properties": {},
+      "message": null
+    },
+    {
+      "name": "foo namespace: has no length property",
+      "status_string": "PASS",
+      "properties": {},
+      "message": null
+    },
+    {
+      "name": "foo namespace: has no name property",
+      "status_string": "PASS",
+      "properties": {},
+      "message": null
+    },
+    {
+      "name": "foo namespace: attribute truth",
+      "status_string": "PASS",
+      "properties": {},
+      "message": null
+    },
+    {
+      "name": "foo namespace: attribute lies",
+      "status_string": "FAIL",
+      "properties": {},
+      "message": "assert_own_property: foo does not have property \"lies\" expected property \"lies\" missing"
+    }
+  ],
+  "type": "complete"
+}
+</script>
+</body>
+</html>
diff --git a/test/wpt/tests/resources/test/tests/functional/idlharness/IdlNamespace/test_operation.html b/test/wpt/tests/resources/test/tests/functional/idlharness/IdlNamespace/test_operation.html
new file mode 100644
index 0000000..da70c8f
--- /dev/null
+++ b/test/wpt/tests/resources/test/tests/functional/idlharness/IdlNamespace/test_operation.html
@@ -0,0 +1,242 @@
+<!DOCTYPE HTML>
+<html>
+<head>
+  <meta charset="utf-8">
+  <title>idlharness: namespace operation</title>
+  <script src="/resources/testharness.js"></script>
+  <script src="/resources/testharnessreport.js"></script>
+  <script src="/resources/WebIDLParser.js"></script>
+  <script src="/resources/idlharness.js"></script>
+</head>
+<body>
+<p>Verify the series of sub-tests that are executed for namespace operations.</p>
+<script>
+"use strict";
+
+Object.defineProperty(self, "foo", {
+  value: Object.defineProperty({}, "Truth", {
+    value: function() {},
+    writable: true,
+    enumerable: true,
+    configurable: true,
+  }),
+  writable: true,
+  enumerable: false,
+  configurable: true,
+});
+
+Object.defineProperty(self, "bar", {
+  value: Object.defineProperty({}, "Truth", {
+    value: function() {},
+    writable: false,
+    enumerable: true,
+    configurable: false,
+  }),
+  writable: true,
+  enumerable: false,
+  configurable: true,
+});
+
+Object.defineProperty(self, "baz", {
+  value: {
+    LongStory: function(hero, ...details) {
+      return `${hero} went and ${details.join(', then')}`
+    },
+    ShortStory: function(...details) {
+      return `${details.join('. ')}`;
+    },
+  },
+  writable: true,
+  enumerable: false,
+  configurable: true,
+});
+
+var idlArray = new IdlArray();
+idlArray.add_idls(`
+[Exposed=Window]
+namespace foo {
+  undefined Truth();
+  undefined Lies();
+};
+[Exposed=Window]
+namespace bar {
+  [LegacyUnforgeable]
+  undefined Truth();
+};
+[Exposed=Window]
+namespace baz {
+  DOMString LongStory(any hero, DOMString... details);
+  DOMString ShortStory(DOMString... details);
+};`);
+idlArray.test();
+</script>
+<script type="text/json" id="expected">
+{
+  "summarized_status": {
+    "status_string": "OK",
+    "message": null
+  },
+  "summarized_tests": [
+    {
+      "name": "foo namespace: extended attributes",
+      "status_string": "PASS",
+      "properties": {},
+      "message": null
+    },
+    {
+      "name": "foo namespace: property descriptor",
+      "status_string": "PASS",
+      "properties": {},
+      "message": null
+    },
+    {
+      "name": "foo namespace: [[Extensible]] is true",
+      "status_string": "PASS",
+      "properties": {},
+      "message": null
+    },
+    {
+      "name": "foo namespace: [[Prototype]] is Object.prototype",
+      "status_string": "PASS",
+      "properties": {},
+      "message": null
+    },
+    {
+      "name": "foo namespace: typeof is \"object\"",
+      "status_string": "PASS",
+      "properties": {},
+      "message": null
+    },
+    {
+      "name": "foo namespace: has no length property",
+      "status_string": "PASS",
+      "properties": {},
+      "message": null
+    },
+    {
+      "name": "foo namespace: has no name property",
+      "status_string": "PASS",
+      "properties": {},
+      "message": null
+    },
+    {
+      "name": "foo namespace: operation Truth()",
+      "status_string": "PASS",
+      "properties": {},
+      "message": null
+    },
+    {
+      "name": "foo namespace: operation Lies()",
+      "status_string": "FAIL",
+      "properties": {},
+      "message": "assert_own_property: namespace object missing operation \"Lies\" expected property \"Lies\" missing"
+    },
+    {
+      "name": "bar namespace: extended attributes",
+      "status_string": "PASS",
+      "properties": {},
+      "message": null
+    },
+    {
+      "name": "bar namespace: property descriptor",
+      "status_string": "PASS",
+      "properties": {},
+      "message": null
+    },
+    {
+      "name": "bar namespace: [[Extensible]] is true",
+      "status_string": "PASS",
+      "properties": {},
+      "message": null
+    },
+    {
+      "name": "bar namespace: [[Prototype]] is Object.prototype",
+      "status_string": "PASS",
+      "properties": {},
+      "message": null
+    },
+    {
+      "name": "bar namespace: typeof is \"object\"",
+      "status_string": "PASS",
+      "properties": {},
+      "message": null
+    },
+    {
+      "name": "bar namespace: has no length property",
+      "status_string": "PASS",
+      "properties": {},
+      "message": null
+    },
+    {
+      "name": "bar namespace: has no name property",
+      "status_string": "PASS",
+      "properties": {},
+      "message": null
+    },
+    {
+      "name": "bar namespace: operation Truth()",
+      "status_string": "PASS",
+      "properties": {},
+      "message": null
+    },
+
+    {
+      "name": "baz namespace: extended attributes",
+      "status_string": "PASS",
+      "properties": {},
+      "message": null
+    },
+    {
+      "name": "baz namespace: property descriptor",
+      "status_string": "PASS",
+      "properties": {},
+      "message": null
+    },
+    {
+      "name": "baz namespace: [[Extensible]] is true",
+      "status_string": "PASS",
+      "properties": {},
+      "message": null
+    },
+    {
+      "name": "baz namespace: [[Prototype]] is Object.prototype",
+      "status_string": "PASS",
+      "properties": {},
+      "message": null
+    },
+    {
+      "name": "baz namespace: typeof is \"object\"",
+      "status_string": "PASS",
+      "properties": {},
+      "message": null
+    },
+    {
+      "name": "baz namespace: has no length property",
+      "status_string": "PASS",
+      "properties": {},
+      "message": null
+    },
+    {
+      "name": "baz namespace: has no name property",
+      "status_string": "PASS",
+      "properties": {},
+      "message": null
+    },
+    {
+      "name": "baz namespace: operation LongStory(any, DOMString...)",
+      "status_string": "PASS",
+      "properties": {},
+      "message": null
+    },
+    {
+      "name": "baz namespace: operation ShortStory(DOMString...)",
+      "status_string": "PASS",
+      "properties": {},
+      "message": null
+    }
+  ],
+  "type": "complete"
+}
+</script>
+</body>
+</html>
diff --git a/test/wpt/tests/resources/test/tests/functional/idlharness/IdlNamespace/test_partial_namespace.html b/test/wpt/tests/resources/test/tests/functional/idlharness/IdlNamespace/test_partial_namespace.html
new file mode 100644
index 0000000..eabdcd1
--- /dev/null
+++ b/test/wpt/tests/resources/test/tests/functional/idlharness/IdlNamespace/test_partial_namespace.html
@@ -0,0 +1,125 @@
+<!DOCTYPE HTML>
+<html>
+
+<head>
+  <meta charset="utf-8">
+  <title>idlharness: Partial namespace</title>
+  <script src="/resources/testharness.js"></script>
+  <script src="/resources/testharnessreport.js"></script>
+  <script src="/resources/WebIDLParser.js"></script>
+  <script src="/resources/idlharness.js"></script>
+</head>
+
+<body>
+  <p>Verify the series of sub-tests that are executed for "partial" namespace objects.</p>
+  <script>
+    "use strict";
+
+    // No original existence
+    (() => {
+      const idlArray = new IdlArray();
+      idlArray.add_idls('partial namespace A {};');
+      idlArray.test();
+    })();
+
+    // Valid exposure (Note: Worker -> {Shared,Dedicated,Service}Worker)
+    (() => {
+      const idlArray = new IdlArray();
+      idlArray.add_untested_idls(`
+        [Exposed=(Worker)]
+        namespace B {};
+
+        [Exposed=(DedicatedWorker, ServiceWorker, SharedWorker)]
+        namespace C {};`);
+      idlArray.add_idls(`
+        [Exposed=(DedicatedWorker, ServiceWorker, SharedWorker)]
+        partial namespace B {};
+
+        [Exposed=(Worker)]
+        partial namespace C {};`);
+      idlArray.merge_partials();
+    })();
+
+    // Invalid exposure
+    (() => {
+      const idlArray = new IdlArray();
+      idlArray.add_untested_idls(`
+        [Exposed=(Window, ServiceWorker)]
+        namespace D {};`);
+      idlArray.add_idls(`
+        [Exposed=(DedicatedWorker)]
+        partial namespace D {};`);
+      idlArray.merge_partials();
+    })();
+
+    // Original is an interface, not a namespace.
+    (() => {
+      const idlArray = new IdlArray();
+      idlArray.add_idls(`
+        partial namespace E {};
+        interface E {};`);
+      idlArray.merge_partials();
+    })();
+  </script>
+  <script type="text/json" id="expected">
+{
+  "summarized_status": {
+    "status_string": "OK",
+    "message": null
+  },
+  "summarized_tests": [
+    {
+      "name": "Partial namespace A: original namespace defined",
+      "status_string": "FAIL",
+      "properties": {},
+      "message": "assert_true: Original namespace should be defined expected true got false"
+    },
+    {
+      "name": "Partial namespace B: original namespace defined",
+      "status_string": "PASS",
+      "properties": {},
+      "message": null
+    },
+    {
+      "name": "Partial namespace B: valid exposure set",
+      "status_string": "PASS",
+      "properties": {},
+      "message": null
+    },
+    {
+      "name": "Partial namespace C: original namespace defined",
+      "status_string": "PASS",
+      "properties": {},
+      "message": null
+    },
+    {
+      "name": "Partial namespace C: valid exposure set",
+      "status_string": "PASS",
+      "properties": {},
+      "message": null
+    },
+    {
+      "name": "Partial namespace D: original namespace defined",
+      "status_string": "PASS",
+      "properties": {},
+      "message": null
+    },
+    {
+      "name": "Partial namespace D: valid exposure set",
+      "status_string": "FAIL",
+      "properties": {},
+      "message": "Partial D namespace is exposed to 'DedicatedWorker', the original namespace is not."
+    },
+    {
+      "name": "Partial namespace E: original namespace defined",
+      "status_string": "FAIL",
+      "properties": {},
+      "message": "assert_true: Original E definition should have type namespace expected true got false"
+    }
+  ],
+  "type": "complete"
+}
+</script>
+</body>
+
+</html>
diff --git a/test/wpt/tests/resources/test/tests/functional/iframe-callback.html b/test/wpt/tests/resources/test/tests/functional/iframe-callback.html
new file mode 100644
index 0000000..f49d0aa
--- /dev/null
+++ b/test/wpt/tests/resources/test/tests/functional/iframe-callback.html
@@ -0,0 +1,116 @@
+<!DOCTYPE HTML>
+<html>
+<head>
+<title>Example with iframe that notifies containing document via callbacks</title>
+<script src="/resources/testharness.js"></script>
+<script src="/resources/testharnessreport.js"></script>
+</head>
+<body onload="start_test_in_iframe()">
+<h1>Callbacks From Tests Running In An IFRAME</h1>
+<p>A test is run inside an <tt>iframe</tt> with a same origin document. The
+containing document should receive callbacks as the tests progress inside the
+<tt>iframe</tt>. A single passing test is expected in the summary below.
+<div id="log"></div>
+
+<script>
+var callbacks = [];
+var START = 1
+var TEST_STATE = 2
+var RESULT = 3
+var COMPLETION = 4
+var test_complete = false;
+
+setup({explicit_done: true});
+
+// The following callbacks are called for tests in this document as well as the
+// tests in the IFRAME. Currently, callbacks invoked from this document and any
+// child document are indistinguishable from each other.
+
+function start_callback(properties) {
+    callbacks.push(START);
+}
+
+function test_state_callback(test) {
+    callbacks.push(TEST_STATE);
+}
+
+function result_callback(test) {
+    callbacks.push(RESULT);
+}
+
+function completion_callback(tests, status) {
+    if (test_complete) {
+        return;
+    }
+    test_complete = true;
+    callbacks.push(COMPLETION);
+    verify_received_callbacks();
+    done();
+}
+
+function verify_received_callbacks() {
+    var copy_of_callbacks = callbacks.slice(0);
+
+    // Note that you can't run test assertions directly in a callback even if
+    // this is a file test. When the callback is invoked from a same-origin child
+    // page, the callstack reaches into the calling child document. Any
+    // exception thrown in a callback will be handled by the child rather than
+    // this document.
+    test(
+        function() {
+            // callbacks list should look like:
+            //     START 1*(TEST_STATE) RESULT COMPLETION
+            assert_equals(copy_of_callbacks.shift(), START,
+                          "The first received callback should be 'start_callback'.");
+            assert_equals(copy_of_callbacks.shift(), TEST_STATE,
+                          "'test_state_callback' should be received before any " +
+                          "result or completion callbacks.");
+            while(copy_of_callbacks.length > 0) {
+                var callback = copy_of_callbacks.shift();
+                if (callback != TEST_STATE) {
+                    copy_of_callbacks.unshift(callback);
+                    break;
+                }
+            }
+            assert_equals(copy_of_callbacks.shift(), RESULT,
+                          "'test_state_callback' should be followed by 'result_callback'.");
+            assert_equals(copy_of_callbacks.shift(), COMPLETION,
+                          "Final 'result_callback' should be followed by 'completion_callback'.");
+            assert_equals(copy_of_callbacks.length, 0,
+                          "'completion_callback' should be the last callback.");
+        });
+}
+
+function start_test_in_iframe() {
+    // This document is going to clear any received callbacks and maintain
+    // radio silence until the test in the iframe runs to completion. The
+    // completion_callback() will then complete the testing on this document.
+    callbacks.length = 0;
+    var iframe = document.createElement("iframe");
+    // single-page-test-pass.html has a single test.
+    iframe.src = "single-page-test-pass.html";
+    iframe.style.setProperty("display", "none");
+    document.getElementById("target").appendChild(iframe);
+}
+</script>
+
+<div id="target">
+</div>
+<script type="text/json" id="expected">
+{
+  "summarized_status": {
+    "status_string": "OK",
+    "message": null
+  },
+  "summarized_tests": [
+    {
+      "status_string": "PASS",
+      "name": "Example with iframe that notifies containing document via callbacks",
+      "properties": {},
+      "message": null
+    }
+  ],
+  "type": "complete"
+}
+</script>
+</body>
diff --git a/test/wpt/tests/resources/test/tests/functional/iframe-consolidate-errors.html b/test/wpt/tests/resources/test/tests/functional/iframe-consolidate-errors.html
new file mode 100644
index 0000000..ef9b870
--- /dev/null
+++ b/test/wpt/tests/resources/test/tests/functional/iframe-consolidate-errors.html
@@ -0,0 +1,50 @@
+<!DOCTYPE HTML>
+<html>
+<head>
+<title>Example with iframe that consolidates errors via fetch_tests_from_window</title>
+<script src="/resources/testharness.js"></script>
+<script src="/resources/testharnessreport.js"></script>
+<script>
+var parent_test = async_test("Test executing in parent context");
+</script>
+</head>
+<body onload="parent_test.done()">
+<h1>Fetching Tests From a Child Context</h1>
+<p>This test demonstrates the use of <tt>fetch_tests_from_window</tt> to pull
+tests from an <tt>iframe</tt> into the primary document.</p>
+<p>The test suite is expected to fail due to an unhandled exception in the
+child context.</p>
+<div id="log"></div>
+
+<iframe id="childContext" src="uncaught-exception-handle.html" style="display:none"></iframe>
+<!-- apisample4.html is a failing suite due to an unhandled Error. -->
+
+<script>
+  var childContext = document.getElementById("childContext");
+  fetch_tests_from_window(childContext.contentWindow);
+</script>
+<script type="text/json" id="expected">
+{
+  "summarized_status": {
+    "status_string": "ERROR",
+    "message": "Error in remote: Error: Example Error"
+  },
+  "summarized_tests": [
+    {
+      "status_string": "PASS",
+      "name": "Test executing in parent context",
+      "properties": {},
+      "message": null
+    },
+    {
+      "status_string": "NOTRUN",
+      "name": "This should show a harness status of 'Error' and a test status of 'Not Run'",
+      "properties": {},
+      "message": null
+    }
+  ],
+  "type": "complete"
+}
+</script>
+</body>
+</html>
diff --git a/test/wpt/tests/resources/test/tests/functional/iframe-consolidate-tests.html b/test/wpt/tests/resources/test/tests/functional/iframe-consolidate-tests.html
new file mode 100644
index 0000000..246ddde
--- /dev/null
+++ b/test/wpt/tests/resources/test/tests/functional/iframe-consolidate-tests.html
@@ -0,0 +1,85 @@
+<!DOCTYPE HTML>
+<html>
+<head>
+<title>Example with iframe that consolidates tests via fetch_tests_from_window</title>
+<script src="/resources/testharness.js"></script>
+<script src="/resources/testharnessreport.js"></script>
+<script>
+var parent_test = async_test("Test executing in parent context");
+</script>
+</head>
+<body onload="parent_test.done()">
+<h1>Fetching Tests From a Child Context</h1>
+<p>This test demonstrates the use of <tt>fetch_tests_from_window</tt> to pull
+tests from an <tt>iframe</tt> into the primary document.</p>
+<p>The test suite will not complete until tests in the child context have finished
+executing</p>
+<div id="log"></div>
+
+<iframe id="childContext" src="promise-async.html" style="display:none"></iframe>
+
+<script>
+  var childContext = document.getElementById("childContext");
+  fetch_tests_from_window(childContext.contentWindow);
+</script>
+<script type="text/json" id="expected">
+{
+  "summarized_status": {
+    "status_string": "OK",
+    "message": null
+  },
+  "summarized_tests": [
+    {
+      "status_string": "PASS",
+      "name": "Promise rejection",
+      "properties": {},
+      "message": null
+    },
+    {
+      "status_string": "PASS",
+      "name": "Promise resolution",
+      "properties": {},
+      "message": null
+    },
+    {
+      "status_string": "FAIL",
+      "name": "Promises and test assertion failures (should fail)",
+      "properties": {},
+      "message": "assert_true: This failure is expected expected true got false"
+    },
+    {
+      "status_string": "PASS",
+      "name": "Promises are supported in your browser",
+      "properties": {},
+      "message": null
+    },
+    {
+      "status_string": "PASS",
+      "name": "Promises resolution chaining",
+      "properties": {},
+      "message": null
+    },
+    {
+      "status_string": "PASS",
+      "name": "Test executing in parent context",
+      "properties": {},
+      "message": null
+    },
+    {
+      "status_string": "PASS",
+      "name": "Use of step_func with Promises",
+      "properties": {},
+      "message": null
+    },
+    {
+      "status_string": "FAIL",
+      "name": "Use of unreached_func with Promises (should fail)",
+      "properties": {},
+      "message": "assert_unreached: This failure is expected Reached unreachable code"
+    }
+  ],
+  "type": "complete"
+}
+</script>
+</body>
+</html>
diff --git a/test/wpt/tests/resources/test/tests/functional/iframe-msg.html b/test/wpt/tests/resources/test/tests/functional/iframe-msg.html
new file mode 100644
index 0000000..283a5d9
--- /dev/null
+++ b/test/wpt/tests/resources/test/tests/functional/iframe-msg.html
@@ -0,0 +1,84 @@
+<!DOCTYPE HTML>
+<html>
+<head>
+<title>Example with iframe that notifies containing document via cross document messaging</title>
+<script src="/resources/testharness.js"></script>
+<script src="/resources/testharnessreport.js"></script>
+</head>
+<body>
+<h1>Notifications From Tests Running In An IFRAME</h1>
+<p>A test is run inside an <tt>iframe</tt> with a same origin document. The
+containing document should receive messages via <tt>postMessage</tt>/
+<tt>onmessage</tt> as the tests progress inside the <tt>iframe</tt>. A single
+passing test is expected in the summary below.
+</p>
+<div id="log"></div>
+
+<script>
+var t = async_test("Containing document receives messages");
+var start_received = false;
+var result_received = false;
+var completion_received = false;
+
+// These are the messages that are expected to be seen while running the tests
+// in the IFRAME.
+var expected_messages = [
+    t.step_func(
+        function(message) {
+            assert_equals(message.data.type, "start");
+            assert_own_property(message.data, "properties");
+        }),
+
+    t.step_func(
+        function(message) {
+            assert_equals(message.data.type, "test_state");
+            assert_equals(message.data.test.status, message.data.test.NOTRUN);
+        }),
+
+    t.step_func(
+        function(message) {
+            assert_equals(message.data.type, "result");
+            assert_equals(message.data.test.status, message.data.test.PASS);
+        }),
+
+    t.step_func(
+        function(message) {
+            assert_equals(message.data.type, "complete");
+            assert_equals(message.data.tests.length, 1);
+            assert_equals(message.data.tests[0].status,
+                          message.data.tests[0].PASS);
+            assert_equals(message.data.status.status, message.data.status.OK);
+            t.done();
+        }),
+
+    t.unreached_func("Too many messages received")
+];
+
+on_event(window,
+         "message",
+         function(message) {
+             var handler = expected_messages.shift();
+             handler(message);
+         });
+</script>
+<iframe src="single-page-test-pass.html" style="display:none">
+  <!-- single-page-test-pass.html implements a file_is_test test. -->
+</iframe>
+<script type="text/json" id="expected">
+{
+  "summarized_status": {
+    "status_string": "OK",
+    "message": null
+  },
+  "summarized_tests": [
+    {
+      "status_string": "PASS",
+      "name": "Containing document receives messages",
+      "properties": {},
+      "message": null
+    }
+  ],
+  "type": "complete"
+}
+</script>
+</body>
diff --git a/test/wpt/tests/resources/test/tests/functional/log-insertion.html b/test/wpt/tests/resources/test/tests/functional/log-insertion.html
new file mode 100644
index 0000000..9a63c3d
--- /dev/null
+++ b/test/wpt/tests/resources/test/tests/functional/log-insertion.html
@@ -0,0 +1,46 @@
+<!DOCTYPE HTML>
+<title>Log insertion</title>
+<script src="/resources/testharness.js"></script>
+<script src="/resources/testharnessreport.js"></script>
+<script>
+test(function(t) {
+  assert_equals(document.body, null);
+}, "Log insertion before load");
+test(function(t) {
+  assert_equals(document.body, null);
+}, "Log insertion before load (again)");
+async_test(function(t) {
+  window.onload = t.step_func_done(function() {
+    var body = document.body;
+    assert_not_equals(body, null);
+
+    var log = document.getElementById("log");
+    assert_equals(log.parentNode, body);
+  });
+}, "Log insertion after load");
+</script>
+<script type="text/json" id="expected">
+{
+  "summarized_status": {
+    "status_string": "OK",
+    "message": null
+  },
+  "summarized_tests": [{
+    "status_string": "PASS",
+    "name": "Log insertion before load",
+    "message": null,
+    "properties": {}
+  }, {
+    "status_string": "PASS",
+    "name": "Log insertion before load (again)",
+    "message": null,
+    "properties": {}
+  }, {
+    "status_string": "PASS",
+    "name": "Log insertion after load",
+    "message": null,
+    "properties": {}
+  }],
+  "type": "complete"
+}
+</script>
diff --git a/test/wpt/tests/resources/test/tests/functional/no-title.html b/test/wpt/tests/resources/test/tests/functional/no-title.html
new file mode 100644
index 0000000..a337e4e
--- /dev/null
+++ b/test/wpt/tests/resources/test/tests/functional/no-title.html
@@ -0,0 +1,146 @@
+<!DOCTYPE HTML>
+<html>
+<head>
+<title>Tests with no title</title>
+</head>
+<script src="/resources/testharness.js"></script>
+
+<body>
+<h1>Tests with no title</h1>
+<div id="log"></div>
+<script>
+  test(function(){assert_true(true, '1')});
+  test(()=>assert_true(true, '2'));
+  test(() => assert_true(true, '3'));
+  test(() => assert_true(true, '3'));  // test duplicate behaviour
+  test(() => assert_true(true, '3'));  // test duplicate behaviour
+  test(() => {
+      assert_true(true, '4');
+  });
+  test(() => { assert_true(true, '5') });
+  test(() => { assert_true(true, '6') }   );
+  test(() => { assert_true(true, '7'); });
+  test(() => {});
+  test(() => { });
+  test(() => {;;;;});
+  test(() => { ; ; ; ; });
+  test(()=>{});
+  test(()=>{ });
+  test(()=>{;;;;});
+  test(()=>{ ; ; ; ; });
+</script>
+<script type="text/json" id="expected">
+{
+  "summarized_status": {
+    "status_string": "OK",
+    "message": null
+  },
+  "summarized_tests": [
+    {
+      "status_string": "PASS",
+      "name": "Tests with no title",
+      "properties": {},
+      "message": null
+    },
+    {
+      "status_string": "PASS",
+      "name": "assert_true(true, '2')",
+      "properties": {},
+      "message": null
+    },
+    {
+      "status_string": "PASS",
+      "name": "assert_true(true, '3')",
+      "properties": {},
+      "message": null
+    },
+    {
+      "status_string": "PASS",
+      "name": "assert_true(true, '3') 1",
+      "properties": {},
+      "message": null
+    },
+    {
+      "status_string": "PASS",
+      "name": "assert_true(true, '3') 2",
+      "properties": {},
+      "message": null
+    },
+    {
+      "status_string": "PASS",
+      "name": "Tests with no title 1",
+      "properties": {},
+      "message": null
+    },
+    {
+      "status_string": "PASS",
+      "name": "assert_true(true, '5')",
+      "properties": {},
+      "message": null
+    },
+    {
+      "status_string": "PASS",
+      "name": "assert_true(true, '6')",
+      "properties": {},
+      "message": null
+    },
+    {
+      "status_string": "PASS",
+      "name": "assert_true(true, '7')",
+      "properties": {},
+      "message": null
+    },
+    {
+      "status_string": "PASS",
+      "name": "Tests with no title 2",
+      "properties": {},
+      "message": null
+    },
+    {
+      "status_string": "PASS",
+      "name": "Tests with no title 3",
+      "properties": {},
+      "message": null
+    },
+    {
+      "status_string": "PASS",
+      "name": "Tests with no title 4",
+      "properties": {},
+      "message": null
+    },
+    {
+      "status_string": "PASS",
+      "name": "Tests with no title 5",
+      "properties": {},
+      "message": null
+    },
+    {
+      "status_string": "PASS",
+      "name": "Tests with no title 6",
+      "properties": {},
+      "message": null
+    },
+    {
+      "status_string": "PASS",
+      "name": "Tests with no title 7",
+      "properties": {},
+      "message": null
+    },
+    {
+      "status_string": "PASS",
+      "name": "Tests with no title 8",
+      "properties": {},
+      "message": null
+    },
+    {
+      "status_string": "PASS",
+      "name": "Tests with no title 9",
+      "properties": {},
+      "message": null
+    }
+  ],
+  "type": "complete"
+}
+</script>
+</body>
+</html>
diff --git a/test/wpt/tests/resources/test/tests/functional/order.html b/test/wpt/tests/resources/test/tests/functional/order.html
new file mode 100644
index 0000000..6863838
--- /dev/null
+++ b/test/wpt/tests/resources/test/tests/functional/order.html
@@ -0,0 +1,36 @@
+<!DOCTYPE HTML>
+<html>
+<head>
+<title>Ordering</title>
+<meta name="timeout" content="6000">
+</head>
+<body>
+<div id="log"></div>
+<script src="/resources/testharness.js"></script>
+<script src="/resources/testharnessreport.js"></script>
+<script>
+test(function() {}, 'second');
+test(function() {}, 'first');
+</script>
+<script type="text/json" id="expected">
+{
+  "summarized_status": {
+    "status_string": "OK",
+    "message": null
+  },
+  "summarized_tests": [{
+    "status_string": "PASS",
+    "name": "first",
+    "message": null,
+    "properties": {}
+  }, {
+    "status_string": "PASS",
+    "name": "second",
+    "message": null,
+    "properties": {}
+  }],
+  "type": "complete"
+}
+</script>
+</body>
+</html>
diff --git a/test/wpt/tests/resources/test/tests/functional/promise-async.html b/test/wpt/tests/resources/test/tests/functional/promise-async.html
new file mode 100644
index 0000000..fa82665
--- /dev/null
+++ b/test/wpt/tests/resources/test/tests/functional/promise-async.html
@@ -0,0 +1,172 @@
+<!DOCTYPE HTML>
+<html>
+<head>
+<title>Async Tests and Promises</title>
+</head>
+<body>
+<h1>Async Tests and Promises</h1>
+<p>This test assumes ECMAScript 6 Promise support. Some failures are expected.</p>
+<div id="log"></div>
+<script src="/resources/testharness.js"></script>
+<script src="/resources/testharnessreport.js"></script>
+<script>
+
+test(function() {
+  var p = new Promise(function(resolve, reject) {});
+  assert_true('then' in p);
+  assert_equals(typeof Promise.resolve, 'function');
+  assert_equals(typeof Promise.reject, 'function');
+}, "Promises are supported in your browser");
+
+(function() {
+  var t = async_test("Promise resolution");
+  t.step(function() {
+    Promise.resolve('x').then(
+      t.step_func(function(value) {
+        assert_equals(value, 'x');
+        t.done();
+      }),
+      t.unreached_func('Promise should not reject')
+    );
+  });
+}());
+
+(function() {
+  var t = async_test("Promise rejection");
+  t.step(function() {
+    Promise.reject(Error('fail')).then(
+      t.unreached_func('Promise should reject'),
+      t.step_func(function(reason) {
+        assert_true(reason instanceof Error);
+        assert_equals(reason.message, 'fail');
+        t.done();
+      })
+    );
+  });
+}());
+
+(function() {
+  var t = async_test("Promises resolution chaining");
+  t.step(function() {
+    var resolutions = [];
+    Promise.resolve('a').then(
+      t.step_func(function(value) {
+        resolutions.push(value);
+        return 'b';
+      })
+    ).then(
+      t.step_func(function(value) {
+        resolutions.push(value);
+        return 'c';
+      })
+    ).then(
+      t.step_func(function(value) {
+        resolutions.push(value);
+
+        assert_array_equals(resolutions, ['a', 'b', 'c']);
+        t.done();
+      })
+    ).catch(
+      t.unreached_func('promise should not have rejected')
+    );
+  });
+}());
+
+(function() {
+  var t = async_test("Use of step_func with Promises");
+  t.step(function() {
+    var resolutions = [];
+    Promise.resolve('x').then(
+      t.step_func_done(),
+      t.unreached_func('Promise should not have rejected')
+    );
+  });
+}());
+
+(function() {
+  var t = async_test("Promises and test assertion failures (should fail)");
+  t.step(function() {
+    var resolutions = [];
+    Promise.resolve('x').then(
+      t.step_func(function(value) {
+        assert_true(false, 'This failure is expected');
+      })
+    ).then(
+      t.unreached_func('Promise should not have resolved')
+    ).catch(
+      t.unreached_func('Promise should not have rejected')
+    );
+  });
+}());
+
+(function() {
+  var t = async_test("Use of unreached_func with Promises (should fail)");
+  t.step(function() {
+    var resolutions = [];
+    var r;
+    var p = new Promise(function(resolve, reject) {
+      // Reject instead of resolve, to demonstrate failure.
+      reject(123);
+    });
+    p.then(
+      function(value) {
+        assert_equals(value, 123, 'This should not actually happen');
+      },
+      t.unreached_func('This failure is expected')
+    );
+  });
+}());
+</script>
+<script type="text/json" id="expected">
+{
+  "summarized_status": {
+    "status_string": "OK",
+    "message": null
+  },
+  "summarized_tests": [
+    {
+      "status_string": "PASS",
+      "name": "Promise rejection",
+      "properties": {},
+      "message": null
+    },
+    {
+      "status_string": "PASS",
+      "name": "Promise resolution",
+      "properties": {},
+      "message": null
+    },
+    {
+      "status_string": "FAIL",
+      "name": "Promises and test assertion failures (should fail)",
+      "properties": {},
+      "message": "assert_true: This failure is expected expected true got false"
+    },
+    {
+      "status_string": "PASS",
+      "name": "Promises are supported in your browser",
+      "properties": {},
+      "message": null
+    },
+    {
+      "status_string": "PASS",
+      "name": "Promises resolution chaining",
+      "properties": {},
+      "message": null
+    },
+    {
+      "status_string": "PASS",
+      "name": "Use of step_func with Promises",
+      "properties": {},
+      "message": null
+    },
+    {
+      "status_string": "FAIL",
+      "name": "Use of unreached_func with Promises (should fail)",
+      "properties": {},
+      "message": "assert_unreached: This failure is expected Reached unreachable code"
+    }
+  ],
+  "type": "complete"
+}
+</script>
diff --git a/test/wpt/tests/resources/test/tests/functional/promise-with-sync.html b/test/wpt/tests/resources/test/tests/functional/promise-with-sync.html
new file mode 100644
index 0000000..e8e680a
--- /dev/null
+++ b/test/wpt/tests/resources/test/tests/functional/promise-with-sync.html
@@ -0,0 +1,79 @@
+<!DOCTYPE HTML>
+<html>
+<head>
+<title>Promise Tests and Synchronous Tests</title>
+</head>
+<body>
+<h1>Promise Tests</h1>
+<p>This test demonstrates the use of <tt>promise_test</tt> alongside synchronous tests.</p>
+<div id="log"></div>
+<script src="../../../testharness.js"></script>
+<script src="../../../testharnessreport.js"></script>
+<script>
+"use strict";
+var sequence = [];
+
+test(function(t) {
+  assert_array_equals(sequence, []);
+  sequence.push(1);
+}, "first synchronous test");
+
+promise_test(function() {
+  assert_array_equals(sequence, [1, 2]);
+
+  return Promise.resolve()
+    .then(function() {
+        assert_array_equals(sequence, [1, 2]);
+        sequence.push(3);
+      });
+}, "first promise_test");;
+
+test(function(t) {
+  assert_array_equals(sequence, [1]);
+  sequence.push(2);
+}, "second synchronous test");
+
+promise_test(function() {
+  assert_array_equals(sequence, [1, 2, 3]);
+
+  return Promise.resolve()
+    .then(function() {
+        assert_array_equals(sequence, [1, 2, 3]);
+      });
+}, "second promise_test");;
+</script>
+<script type="text/json" id="expected">
+{
+  "summarized_status": {
+    "message": null,
+    "status_string": "OK"
+  },
+  "summarized_tests": [
+    {
+      "message": null,
+      "properties": {},
+      "name": "first promise_test",
+      "status_string": "PASS"
+    },
+    {
+      "message": null,
+      "properties": {},
+      "name": "first synchronous test",
+      "status_string": "PASS"
+    },
+    {
+      "message": null,
+      "properties": {},
+      "name": "second promise_test",
+      "status_string": "PASS"
+    },
+    {
+      "message": null,
+      "properties": {},
+      "name": "second synchronous test",
+      "status_string": "PASS"
+    }
+  ],
+  "type": "complete"
+}
+</script>
diff --git a/test/wpt/tests/resources/test/tests/functional/promise.html b/test/wpt/tests/resources/test/tests/functional/promise.html
new file mode 100644
index 0000000..f35feb0
--- /dev/null
+++ b/test/wpt/tests/resources/test/tests/functional/promise.html
@@ -0,0 +1,219 @@
+<!DOCTYPE HTML>
+<html>
+<head>
+<title>Promise Tests</title>
+</head>
+<body>
+<h1>Promise Tests</h1>
+<p>This test demonstrates the use of <tt>promise_test</tt>. Assumes ECMAScript 6
+Promise support. Some failures are expected.</p>
+<div id="log"></div>
+<script src="/resources/testharness.js"></script>
+<script src="/resources/testharnessreport.js"></script>
+<script>
+test(
+    function() {
+        var p = new Promise(function(resolve, reject){});
+        assert_true("then" in p);
+        assert_equals(typeof Promise.resolve, "function");
+        assert_equals(typeof Promise.reject, "function");
+    },
+    "Promises are supported in your browser");
+
+promise_test(
+    function() {
+        return Promise.resolve("x")
+            .then(
+                function(value) {
+                    assert_equals(value,
+                                  "x",
+                                  "Fulfilled promise should pass result to " +
+                                  "fulfill reaction.");
+                });
+    },
+    "Promise fulfillment with result");
+
+promise_test(
+    function(t) {
+        return Promise.reject(new Error("fail"))
+            .then(t.unreached_func("Promise should reject"),
+                function(reason) {
+                    assert_true(
+                        reason instanceof Error,
+                        "Rejected promise should pass reason to fulfill reaction.");
+                    assert_equals(
+                        reason.message,
+                        "fail",
+                        "Rejected promise should pass reason to reject reaction.");
+                });
+    },
+    "Promise rejection with result");
+
+promise_test(
+    function() {
+        var resolutions = [];
+        return Promise.resolve("a")
+            .then(
+                function(value) {
+                    resolutions.push(value);
+                    return "b";
+                })
+            .then(
+                function(value) {
+                    resolutions.push(value);
+                    return "c";
+                })
+            .then(
+                function(value) {
+                    resolutions.push(value);
+                    assert_array_equals(resolutions, ["a", "b", "c"]);
+                });
+    },
+    "Chain of promise resolutions");
+
+promise_test(
+    function(t) {
+        var resolutions = [];
+        return Promise.resolve("x")
+            .then(
+                function(value) {
+                    assert_true(false, "Expected failure.");
+                })
+            .then(t.unreached_func("UNEXPECTED FAILURE: Promise should not have resolved."));
+    },
+    "Assertion failure in a fulfill reaction (should FAIL with an expected failure)");
+
+promise_test(
+    function(t) {
+        return new Promise(
+                function(resolve, reject) {
+                    reject(123);
+                })
+            .then(t.unreached_func("UNEXPECTED FAILURE: Fulfill reaction reached after rejection."),
+                  t.unreached_func("Expected failure."));
+    },
+    "unreached_func as reactor (should FAIL with an expected failure)");
+
+promise_test(
+    function() {
+        return true;
+    },
+    "promise_test with function that doesn't return a Promise (should FAIL)");
+
+promise_test(function(){},
+             "promise_test with function that doesn't return anything");
+
+promise_test(
+    function() { return { then: 23 }; },
+    "promise_test that returns a non-thenable (should FAIL)");
+
+promise_test(
+    function() {
+        return Promise.reject("Expected rejection");
+    },
+    "promise_test with unhandled rejection (should FAIL)");
+
+promise_test(
+    function() {
+        return Promise.resolve(10)
+            .then(
+                function(value) {
+                    throw Error("Expected exception.");
+                });
+    },
+    "promise_test with unhandled exception in fulfill reaction (should FAIL)");
+
+promise_test(
+    function(t) {
+        return Promise.reject(10)
+            .then(
+                t.unreached_func("UNEXPECTED FAILURE: Fulfill reaction reached after rejection."),
+                function(value) {
+                    throw Error("Expected exception.");
+                });
+    },
+    "promise_test with unhandled exception in reject reaction (should FAIL)");
+</script>
+<script type="text/json" id="expected">
+{
+  "summarized_status": {
+    "status_string": "OK",
+    "message": null
+  },
+  "summarized_tests": [
+    {
+      "status_string": "FAIL",
+      "name": "Assertion failure in a fulfill reaction (should FAIL with an expected failure)",
+      "message": "assert_true: Expected failure. expected true got false",
+      "properties": {}
+    },
+    {
+      "status_string": "PASS",
+      "name": "Chain of promise resolutions",
+      "message": null,
+      "properties": {}
+    },
+    {
+      "status_string": "PASS",
+      "name": "Promise fulfillment with result",
+      "message": null,
+      "properties": {}
+    },
+    {
+      "status_string": "PASS",
+      "name": "Promise rejection with result",
+      "message": null,
+      "properties": {}
+    },
+    {
+      "status_string": "PASS",
+      "name": "Promises are supported in your browser",
+      "message": null,
+      "properties": {}
+    },
+    {
+      "status_string": "FAIL",
+      "name": "promise_test with function that doesn't return a Promise (should FAIL)",
+      "message": "promise_test: test body must return a 'thenable' object (received an object with no `then` method)",
+      "properties": {}
+    },
+    {
+      "status_string": "FAIL",
+      "name": "promise_test with function that doesn't return anything",
+      "message": "promise_test: test body must return a 'thenable' object (received undefined)",
+      "properties": {}
+    },
+    {
+      "status_string": "FAIL",
+      "name": "promise_test that returns a non-thenable (should FAIL)",
+      "message": "promise_test: test body must return a 'thenable' object (received an object with no `then` method)",
+      "properties": {}
+    },
+    {
+      "status_string": "FAIL",
+      "name": "promise_test with unhandled exception in fulfill reaction (should FAIL)",
+      "message": "promise_test: Unhandled rejection with value: object \"Error: Expected exception.\"",
+      "properties": {}
+    },
+    {
+      "status_string": "FAIL",
+      "name": "promise_test with unhandled exception in reject reaction (should FAIL)",
+      "message": "promise_test: Unhandled rejection with value: object \"Error: Expected exception.\"",
+      "properties": {}
+    },
+    {
+      "status_string": "FAIL",
+      "name": "promise_test with unhandled rejection (should FAIL)",
+      "message": "promise_test: Unhandled rejection with value: \"Expected rejection\"",
+      "properties": {}
+    },
+    {
+      "status_string": "FAIL",
+      "name": "unreached_func as reactor (should FAIL with an expected failure)",
+      "message": "assert_unreached: Expected failure. Reached unreachable code",
+      "properties": {}
+    }
+  ],
+  "type": "complete"
+}
+</script>
diff --git a/test/wpt/tests/resources/test/tests/functional/queue.html b/test/wpt/tests/resources/test/tests/functional/queue.html
new file mode 100644
index 0000000..0c72128
--- /dev/null
+++ b/test/wpt/tests/resources/test/tests/functional/queue.html
@@ -0,0 +1,130 @@
+<!DOCTYPE HTML>
+<html>
+<head>
+<title>Test queuing synchronous tests</title>
+<script src="../../../testharness.js"></script>
+<script src="../../../testharnessreport.js"></script>
+</head>
+<body>
+<div id="log"></div>
+
+<script>
+"use strict";
+var inInitialTurn = true;
+
+test(function(t) {
+  assert_true(
+    inInitialTurn, "should execute in the initial turn of the event loop"
+  );
+}, "First synchronous test");
+
+test(function(t) {
+  assert_true(
+    inInitialTurn, "should execute in the initial turn of the event loop"
+  );
+}, "Second synchronous test");
+
+async_test(function(t) {
+  assert_true(
+    inInitialTurn, "should execute in the initial turn of the event loop"
+  );
+  t.done();
+}, "First async_test (run in parallel)");
+
+async_test(function(t) {
+  assert_true(
+    inInitialTurn, "should execute in the initial turn of the event loop"
+  );
+  t.done();
+}, "Second async_test (run in parallel)");
+
+test(function(t) {
+  assert_true(
+    inInitialTurn, "should execute in the initial turn of the event loop"
+  );
+}, "Third synchronous test");
+
+promise_test(function(t) {
+  assert_false(
+    inInitialTurn, "should not execute in the initial turn of the event loop"
+  );
+
+  return Promise.resolve();
+}, "promise_test");
+
+async_test(function(t) {
+  assert_true(
+    inInitialTurn, "should execute in the initial turn of the event loop"
+  );
+  t.done();
+}, "Third async_test (run in parallel)");
+
+test(function(t) {
+  assert_true(
+    inInitialTurn, "should execute in the initial turn of the event loop"
+  );
+}, "Fourth synchronous test");
+
+inInitialTurn = false;
+</script>
+<script type="text/json" id="expected">
+{
+  "summarized_status": {
+    "status_string": "OK",
+    "message": null
+  },
+  "summarized_tests": [
+    {
+      "properties": {},
+      "name": "First async_test (run in parallel)",
+      "status_string": "PASS",
+      "message": null
+    },
+    {
+      "properties": {},
+      "name": "First synchronous test",
+      "status_string": "PASS",
+      "message": null
+    },
+    {
+      "properties": {},
+      "name": "Fourth synchronous test",
+      "status_string": "PASS",
+      "message": null
+    },
+    {
+      "properties": {},
+      "name": "Second async_test (run in parallel)",
+      "status_string": "PASS",
+      "message": null
+    },
+    {
+      "properties": {},
+      "name": "Second synchronous test",
+      "status_string": "PASS",
+      "message": null
+    },
+    {
+      "properties": {},
+      "name": "Third async_test (run in parallel)",
+      "status_string": "PASS",
+      "message": null
+    },
+    {
+      "properties": {},
+      "name": "Third synchronous test",
+      "status_string": "PASS",
+      "message": null
+    },
+    {
+      "properties": {},
+      "name": "promise_test",
+      "status_string": "PASS",
+      "message": null
+    }
+  ],
+  "type": "complete"
+}
+</script>
+</body>
+</html>
diff --git a/test/wpt/tests/resources/test/tests/functional/setup-function-worker.js b/test/wpt/tests/resources/test/tests/functional/setup-function-worker.js
new file mode 100644
index 0000000..82c1456
--- /dev/null
+++ b/test/wpt/tests/resources/test/tests/functional/setup-function-worker.js
@@ -0,0 +1,14 @@
+importScripts("/resources/testharness.js");
+
+// Regression test for https://github.com/web-platform-tests/wpt/issues/27299,
+// where we broke the ability for a setup function in a worker to contain an
+// assertion (even a passing one).
+setup(function() {
+    assert_true(true, "True is true");
+});
+
+// We must define at least one test for the harness, though it is not what we
+// are testing here.
+test(function() {
+    assert_false(false, "False is false");
+}, 'Worker test');
diff --git a/test/wpt/tests/resources/test/tests/functional/setup-worker-service.html b/test/wpt/tests/resources/test/tests/functional/setup-worker-service.html
new file mode 100644
index 0000000..9f24ada
--- /dev/null
+++ b/test/wpt/tests/resources/test/tests/functional/setup-worker-service.html
@@ -0,0 +1,86 @@
+<!DOCTYPE HTML>
+<html>
+<head>
+<title>Setup function in a service worker</title>
+<script src="/resources/testharness.js"></script>
+<script src="/resources/testharnessreport.js"></script>
+</head>
+<body>
+<h1>Setup function in a service worker</h1>
+<p>This test assumes that the browser supports <a href="http://www.w3.org/TR/service-workers/">ServiceWorkers</a>.
+<div id="log"></div>
+
+<script>
+test(function(t) {
+    assert_true("serviceWorker" in navigator,
+                "navigator.serviceWorker exists");
+}, "Browser supports ServiceWorker");
+
+promise_test(function() {
+    // Since the service worker registration could be in an indeterminate
+    // state (due to, for example, a previous test run failing), we start by
+    // unregstering our service worker and then registering it again.
+    var scope = "service-worker-scope";
+    var worker_url = "setup-function-worker.js";
+
+    return navigator.serviceWorker.register(worker_url, {scope: scope})
+        .then(function(registration) {
+            return registration.unregister();
+        }).then(function() {
+            return navigator.serviceWorker.register(worker_url, {scope: scope});
+        }).then(function(registration) {
+            add_completion_callback(function() {
+                registration.unregister();
+            });
+
+            return new Promise(function(resolve) {
+                registration.addEventListener("updatefound", function() {
+                    resolve(registration.installing);
+                });
+            });
+        }).then(function(worker) {
+            fetch_tests_from_worker(worker);
+        });
+}, "Register ServiceWorker");
+</script>
+<script type="text/json" id="expected">
+{
+  "summarized_status": {
+    "status_string": "OK",
+    "message": null
+  },
+  "summarized_tests": [
+    {
+      "status_string": "PASS",
+      "name": "Browser supports ServiceWorker",
+      "properties": {},
+      "message": null
+    },
+    {
+      "message": null,
+      "name": "Register ServiceWorker",
+      "properties": {},
+      "status_string": "PASS"
+    },
+    {
+      "message": null,
+      "name": "Worker test",
+      "properties": {},
+      "status_string": "PASS"
+    }
+  ],
+  "summarized_asserts": [
+    {
+      "assert_name": "assert_true",
+      "test": "Browser supports ServiceWorker",
+      "args": [
+        "true",
+        "\"navigator.serviceWorker exists\""
+      ],
+      "status": 0
+    }
+  ],
+  "type": "complete"
+}
+</script>
+</body>
diff --git a/test/wpt/tests/resources/test/tests/functional/single-page-test-fail.html b/test/wpt/tests/resources/test/tests/functional/single-page-test-fail.html
new file mode 100644
index 0000000..8bbd530
--- /dev/null
+++ b/test/wpt/tests/resources/test/tests/functional/single-page-test-fail.html
@@ -0,0 +1,28 @@
+<!DOCTYPE HTML>
+<title>Example with file_is_test (should fail)</title>
+<script src="/resources/testharness.js"></script>
+<script src="/resources/testharnessreport.js"></script>
+<script>
+setup({ single_test: true });
+onload = function() {
+  assert_true(false);
+  done();
+}
+</script>
+<script type="text/json" id="expected">
+{
+  "summarized_status": {
+    "status_string": "OK",
+    "message": null
+  },
+  "summarized_tests": [
+    {
+      "status_string": "FAIL",
+      "name": "Example with file_is_test (should fail)",
+      "properties": {},
+      "message": "uncaught exception: Error: assert_true: expected true got false"
+    }
+  ],
+  "type": "complete"
+}
+</script>
diff --git a/test/wpt/tests/resources/test/tests/functional/single-page-test-no-assertions.html b/test/wpt/tests/resources/test/tests/functional/single-page-test-no-assertions.html
new file mode 100644
index 0000000..9b39d2a
--- /dev/null
+++ b/test/wpt/tests/resources/test/tests/functional/single-page-test-no-assertions.html
@@ -0,0 +1,25 @@
+<!DOCTYPE HTML>
+<title>Example single page test with no asserts</title>
+<script src="/resources/testharness.js"></script>
+<script src="/resources/testharnessreport.js"></script>
+<script>
+setup({ single_test: true });
+done();
+</script>
+<script type="text/json" id="expected">
+{
+  "summarized_status": {
+    "status_string": "OK",
+    "message": null
+  },
+  "summarized_tests": [
+    {
+      "status_string": "PASS",
+      "name": "Example single page test with no asserts",
+      "properties": {},
+      "message": null
+    }
+  ],
+  "type": "complete"
+}
+</script>
diff --git a/test/wpt/tests/resources/test/tests/functional/single-page-test-no-body.html b/test/wpt/tests/resources/test/tests/functional/single-page-test-no-body.html
new file mode 100644
index 0000000..cb018f4
--- /dev/null
+++ b/test/wpt/tests/resources/test/tests/functional/single-page-test-no-body.html
@@ -0,0 +1,26 @@
+<!DOCTYPE HTML>
+<title>Example single page test with no body</title>
+<script src="/resources/testharness.js"></script>
+<script src="/resources/testharnessreport.js"></script>
+<script>
+setup({ single_test: true });
+assert_true(true);
+done();
+</script>
+<script type="text/json" id="expected">
+{
+  "summarized_status": {
+    "status_string": "OK",
+    "message": null
+  },
+  "summarized_tests": [
+    {
+      "status_string": "PASS",
+      "name": "Example single page test with no body",
+      "properties": {},
+      "message": null
+    }
+  ],
+  "type": "complete"
+}
+</script>
diff --git a/test/wpt/tests/resources/test/tests/functional/single-page-test-pass.html b/test/wpt/tests/resources/test/tests/functional/single-page-test-pass.html
new file mode 100644
index 0000000..e143e22
--- /dev/null
+++ b/test/wpt/tests/resources/test/tests/functional/single-page-test-pass.html
@@ -0,0 +1,28 @@
+<!DOCTYPE HTML>
+<title>Example with file_is_test</title>
+<script src="/resources/testharness.js"></script>
+<script src="/resources/testharnessreport.js"></script>
+<script>
+setup({ single_test: true });
+onload = function() {
+  assert_true(true);
+  done();
+}
+</script>
+<script type="text/json" id="expected">
+{
+  "summarized_status": {
+    "status_string": "OK",
+    "message": null
+  },
+  "summarized_tests": [
+    {
+      "status_string": "PASS",
+      "name": "Example with file_is_test",
+      "properties": {},
+      "message": null
+    }
+  ],
+  "type": "complete"
+}
+</script>
diff --git a/test/wpt/tests/resources/test/tests/functional/step_wait.html b/test/wpt/tests/resources/test/tests/functional/step_wait.html
new file mode 100644
index 0000000..ae3442c
--- /dev/null
+++ b/test/wpt/tests/resources/test/tests/functional/step_wait.html
@@ -0,0 +1,57 @@
+<!doctype html>
+<title>Tests for step_wait</title>
+<script src=/resources/testharness.js></script>
+<script src=/resources/testharnessreport.js></script>
+<div id=log></div>
+<script>
+promise_test(async t => {
+  let x = 1;
+  Promise.resolve().then(() => ++x);
+  await t.step_wait(() => x === 1);
+  assert_equals(x, 2);
+}, "Basic step_wait() test");
+
+promise_test(async t => {
+  let cond = false;
+  let x = 0;
+  setTimeout(() => cond = true, 100);
+  await t.step_wait(() => {
+    ++x;
+    return cond;
+  });
+  assert_equals(x, 2);
+}, "step_wait() isn't invoked too often");
+
+promise_test(async t => {
+  await t.step_wait(); // Throws
+}, "step_wait() takes an argument");
+</script>
+<script type="text/json" id="expected">
+{
+  "summarized_tests": [
+    {
+      "name": "Basic step_wait() test",
+      "message": null,
+      "properties": {},
+      "status_string": "PASS"
+    },
+    {
+      "name": "step_wait() isn't invoked too often",
+      "message": null,
+      "properties": {},
+      "status_string": "PASS"
+    },
+    {
+      "name": "step_wait() takes an argument",
+      "message": "cond is not a function",
+      "properties": {},
+      "status_string": "FAIL"
+    }
+  ],
+  "type": "complete",
+  "summarized_status": {
+    "status_string": "OK",
+    "message": null
+  }
+}
+</script>
diff --git a/test/wpt/tests/resources/test/tests/functional/step_wait_func.html b/test/wpt/tests/resources/test/tests/functional/step_wait_func.html
new file mode 100644
index 0000000..9fed18a
--- /dev/null
+++ b/test/wpt/tests/resources/test/tests/functional/step_wait_func.html
@@ -0,0 +1,49 @@
+<!doctype html>
+<title>Tests for step_wait_func and step_wait_func_done</title>
+<script src=/resources/testharness.js></script>
+<script src=/resources/testharnessreport.js></script>
+<div id=log></div>
+<script>
+async_test(t => {
+  let x = 0;
+  let step_x = 0;
+  setTimeout(() => ++x, 100);
+  t.step_wait_func(() => {
+    ++step_x;
+    return x === 1;
+  }, () => {
+    assert_equals(step_x, 2);
+    t.done();
+  });
+}, "Basic step_wait_func() test");
+
+async_test(t => {
+  let x = 0;
+  setTimeout(() => ++x, 100);
+  t.step_wait_func_done(() => true, () => assert_equals(x, 0));
+}, "Basic step_wait_func_done() test");
+
+</script>
+<script type="text/json" id="expected">
+{
+  "summarized_status": {
+    "message": null,
+    "status_string": "OK"
+  },
+  "summarized_tests": [
+    {
+      "properties": {},
+      "message": null,
+      "name": "Basic step_wait_func() test",
+      "status_string": "PASS"
+    },
+    {
+      "properties": {},
+      "message": null,
+      "name": "Basic step_wait_func_done() test",
+      "status_string": "PASS"
+    }
+  ],
+  "type": "complete"
+}
+</script>
diff --git a/test/wpt/tests/resources/test/tests/functional/task-scheduling-promise-test.html b/test/wpt/tests/resources/test/tests/functional/task-scheduling-promise-test.html
new file mode 100644
index 0000000..9d8e5c1
--- /dev/null
+++ b/test/wpt/tests/resources/test/tests/functional/task-scheduling-promise-test.html
@@ -0,0 +1,241 @@
+<!doctype html>
+<title>testharness.js - task scheduling</title>
+<script src="../../../testharness.js"></script>
+<script src="../../../testharnessreport.js"></script>
+<script>
+var sameTask = null;
+var sameMicrotask = null;
+var expectedError = new Error('This error is expected');
+
+promise_test(function() {
+  return Promise.resolve()
+    .then(function() {
+        sameMirotask = true;
+        Promise.resolve().then(() => sameMicrotask = false);
+      });
+}, 'promise test without cleanup #1');
+
+promise_test(function() {
+  assert_false(sameMicrotask);
+
+  return Promise.resolve();
+}, 'sub-test with 0 cleanup functions executes in distinct microtask from a passing sub-test');
+
+promise_test(function() {
+  return Promise.resolve()
+    .then(function() {
+        sameMirotask = true;
+        Promise.resolve().then(() => sameMicrotask = false);
+        throw expectedError;
+      });
+}, 'failing promise test without cleanup #1');
+
+promise_test(function() {
+  assert_false(sameMicrotask);
+
+  return Promise.resolve();
+}, 'sub-test with 0 cleanup functions executes in distinct microtask from a failing sub-test');
+
+promise_test(function(t) {
+  t.add_cleanup(function() {});
+
+  return Promise.resolve()
+    .then(function() {
+        sameMirotask = true;
+        Promise.resolve().then(() => sameMicrotask = false);
+      });
+}, 'promise test with cleanup #1');
+
+promise_test(function() {
+  assert_false(sameMicrotask);
+
+  return Promise.resolve();
+}, 'sub-test with some cleanup functions executes in distinct microtask from a passing sub-test');
+
+promise_test(function(t) {
+  t.add_cleanup(function() {});
+
+  return Promise.resolve()
+    .then(function() {
+        sameMirotask = true;
+        Promise.resolve().then(() => sameMicrotask = false);
+        throw expectedError;
+      });
+}, 'failing promise test with cleanup #1');
+
+promise_test(function() {
+  assert_false(sameMicrotask);
+
+  return Promise.resolve();
+}, 'sub-test with some cleanup functions executes in distinct microtask from a failing sub-test');
+
+promise_test(function(t) {
+  return Promise.resolve()
+    .then(function() {
+        sameTask = true;
+        t.step_timeout(() => sameTask = false, 0);
+      });
+}, 'promise test without cleanup #2');
+
+promise_test(function() {
+  assert_true(sameTask);
+
+  return Promise.resolve();
+}, 'sub-test with 0 cleanup functions executes in the same task as a passing sub-test');
+
+promise_test(function(t) {
+  return Promise.resolve()
+    .then(function() {
+        sameTask = true;
+        t.step_timeout(() => sameTask = false, 0);
+        throw expectedError;
+      });
+}, 'failing promise test without cleanup #2');
+
+promise_test(function() {
+  assert_true(sameTask);
+
+  return Promise.resolve();
+}, 'sub-test with 0 cleanup functions executes in the same task as a failing sub-test');
+
+promise_test(function(t) {
+  t.add_cleanup(function() {});
+
+  return Promise.resolve()
+    .then(function() {
+        sameTask = true;
+        t.step_timeout(() => sameTask = false, 0);
+      });
+}, 'promise test with cleanup #2');
+
+promise_test(function() {
+  assert_true(sameTask);
+
+  return Promise.resolve();
+}, 'sub-test with some cleanup functions executes in the same task as a passing sub-test');
+
+promise_test(function(t) {
+  t.add_cleanup(function() {});
+
+  return Promise.resolve()
+    .then(function() {
+        sameTask = true;
+        t.step_timeout(() => sameTask = false, 0);
+        throw expectedError;
+      });
+}, 'failing promise test with cleanup #2');
+
+promise_test(function() {
+  assert_true(sameTask);
+
+  return Promise.resolve();
+}, 'sub-test with some cleanup functions executes in the same task as a failing sub-test');
+</script>
+
+<script type="text/json" id="expected">
+{
+    "summarized_status": {
+        "message": null,
+        "status_string": "OK"
+    },
+    "summarized_tests": [
+        {
+            "message": "promise_test: Unhandled rejection with value: object \"Error: This error is expected\"",
+            "name": "failing promise test with cleanup #1",
+            "properties": {},
+            "status_string": "FAIL"
+        },
+        {
+            "message": "promise_test: Unhandled rejection with value: object \"Error: This error is expected\"",
+            "name": "failing promise test with cleanup #2",
+            "properties": {},
+            "status_string": "FAIL"
+        },
+        {
+            "message": "promise_test: Unhandled rejection with value: object \"Error: This error is expected\"",
+            "name": "failing promise test without cleanup #1",
+            "properties": {},
+            "status_string": "FAIL"
+        },
+        {
+            "message": "promise_test: Unhandled rejection with value: object \"Error: This error is expected\"",
+            "name": "failing promise test without cleanup #2",
+            "properties": {},
+            "status_string": "FAIL"
+        },
+        {
+            "message": null,
+            "name": "promise test with cleanup #1",
+            "properties": {},
+            "status_string": "PASS"
+        },
+        {
+            "message": null,
+            "name": "promise test with cleanup #2",
+            "properties": {},
+            "status_string": "PASS"
+        },
+        {
+            "message": null,
+            "name": "promise test without cleanup #1",
+            "properties": {},
+            "status_string": "PASS"
+        },
+        {
+            "message": null,
+            "name": "promise test without cleanup #2",
+            "properties": {},
+            "status_string": "PASS"
+        },
+        {
+            "message": null,
+            "name": "sub-test with 0 cleanup functions executes in distinct microtask from a failing sub-test",
+            "properties": {},
+            "status_string": "PASS"
+        },
+        {
+            "message": null,
+            "name": "sub-test with 0 cleanup functions executes in distinct microtask from a passing sub-test",
+            "properties": {},
+            "status_string": "PASS"
+        },
+        {
+            "message": null,
+            "name": "sub-test with 0 cleanup functions executes in the same task as a failing sub-test",
+            "properties": {},
+            "status_string": "PASS"
+        },
+        {
+            "message": null,
+            "name": "sub-test with 0 cleanup functions executes in the same task as a passing sub-test",
+            "properties": {},
+            "status_string": "PASS"
+        },
+        {
+            "message": null,
+            "name": "sub-test with some cleanup functions executes in distinct microtask from a failing sub-test",
+            "properties": {},
+            "status_string": "PASS"
+        },
+        {
+            "message": null,
+            "name": "sub-test with some cleanup functions executes in distinct microtask from a passing sub-test",
+            "properties": {},
+            "status_string": "PASS"
+        },
+        {
+            "message": null,
+            "name": "sub-test with some cleanup functions executes in the same task as a failing sub-test",
+            "properties": {},
+            "status_string": "PASS"
+        },
+        {
+            "message": null,
+            "name": "sub-test with some cleanup functions executes in the same task as a passing sub-test",
+            "properties": {},
+            "status_string": "PASS"
+        }
+    ],
+    "type": "complete"
+}
+</script>
diff --git a/test/wpt/tests/resources/test/tests/functional/task-scheduling-test.html b/test/wpt/tests/resources/test/tests/functional/task-scheduling-test.html
new file mode 100644
index 0000000..0358444
--- /dev/null
+++ b/test/wpt/tests/resources/test/tests/functional/task-scheduling-test.html
@@ -0,0 +1,141 @@
+<!doctype html>
+<title>testharness.js - task scheduling</title>
+<script src="../../../testharness.js"></script>
+<script src="../../../testharnessreport.js"></script>
+<script>
+var sameMicrotask = null;
+var expectedError = new Error('This error is expected');
+
+// Derived from `immediate`
+// https://github.com/calvinmetcalf/immediate/blob/c353bd2106648cee1d525bfda22cfc4456e69c0e/lib/mutation.js
+function microTask(callback) {
+  var observer = new MutationObserver(callback);
+  var element = document.createTextNode('');
+  observer.observe(element, {
+    characterData: true
+  });
+
+  element.data = true;
+};
+
+async_test(function(t) {
+  var microtask_ran = false;
+
+  t.step_timeout(t.step_func(function() {
+    assert_true(microtask_ran, 'function registered as a microtask was executed before task');
+    t.done();
+  }), 0);
+
+  microTask(function() {
+    microtask_ran = true;
+  });
+}, 'precondition: microtask creation logic functions as expected');
+
+test(function() {
+  sameMicrotask = true;
+  microTask(function() { sameMicrotask = false; });
+}, 'synchronous test without cleanup');
+
+test(function() {
+  assert_true(sameMicrotask);
+}, 'sub-test with 0 cleanup functions executes in the same microtask as a passing sub-test');
+
+test(function() {
+  sameMicrotask = true;
+  microTask(function() { sameMicrotask = false; });
+  throw expectedError;
+}, 'failing synchronous test without cleanup');
+
+test(function() {
+  assert_true(sameMicrotask);
+}, 'sub-test with 0 cleanup functions executes in the same microtask as a failing sub-test');
+
+test(function(t) {
+  t.add_cleanup(function() {});
+
+  sameMicrotask = true;
+  microTask(function() { sameMicrotask = false; });
+}, 'synchronous test with cleanup');
+
+test(function() {
+  assert_true(sameMicrotask);
+}, 'sub-test with some cleanup functions executes in the same microtask as a passing sub-test');
+
+test(function(t) {
+  t.add_cleanup(function() {});
+
+  sameMicrotask = true;
+  microTask(function() { sameMicrotask = false; });
+  throw expectedError;
+}, 'failing synchronous test with cleanup');
+
+test(function() {
+  assert_true(sameMicrotask);
+}, 'sub-test with some cleanup functions executes in the same microtask as a failing sub-test');
+</script>
+
+<script type="text/json" id="expected">
+{
+    "summarized_status": {
+        "message": null,
+        "status_string": "OK"
+    },
+    "summarized_tests": [
+        {
+            "message": "This error is expected",
+            "name": "failing synchronous test with cleanup",
+            "properties": {},
+            "status_string": "FAIL"
+        },
+        {
+            "message": "This error is expected",
+            "name": "failing synchronous test without cleanup",
+            "properties": {},
+            "status_string": "FAIL"
+        },
+        {
+            "message": null,
+            "name": "precondition: microtask creation logic functions as expected",
+            "properties": {},
+            "status_string": "PASS"
+        },
+        {
+            "message": null,
+            "name": "sub-test with 0 cleanup functions executes in the same microtask as a failing sub-test",
+            "properties": {},
+            "status_string": "PASS"
+        },
+        {
+            "message": null,
+            "name": "sub-test with 0 cleanup functions executes in the same microtask as a passing sub-test",
+            "properties": {},
+            "status_string": "PASS"
+        },
+        {
+            "message": null,
+            "name": "sub-test with some cleanup functions executes in the same microtask as a failing sub-test",
+            "properties": {},
+            "status_string": "PASS"
+        },
+        {
+            "message": null,
+            "name": "sub-test with some cleanup functions executes in the same microtask as a passing sub-test",
+            "properties": {},
+            "status_string": "PASS"
+        },
+        {
+            "message": null,
+            "name": "synchronous test with cleanup",
+            "properties": {},
+            "status_string": "PASS"
+        },
+        {
+            "message": null,
+            "name": "synchronous test without cleanup",
+            "properties": {},
+            "status_string": "PASS"
+        }
+    ],
+    "type": "complete"
+}
+</script>
diff --git a/test/wpt/tests/resources/test/tests/functional/uncaught-exception-handle.html b/test/wpt/tests/resources/test/tests/functional/uncaught-exception-handle.html
new file mode 100644
index 0000000..764b0c4
--- /dev/null
+++ b/test/wpt/tests/resources/test/tests/functional/uncaught-exception-handle.html
@@ -0,0 +1,33 @@
+<!DOCTYPE HTML>
+<html>
+<head>
+<title>Harness Handling Uncaught Exception</title>
+</head>
+<script src="/resources/testharness.js"></script>
+
+<body>
+<h1>Harness Handling Uncaught Exception</h1>
+<div id="log"></div>
+<script>
+var t = async_test("This should show a harness status of 'Error' and a test status of 'Not Run'");
+throw new Error("Example Error");
+</script>
+<script type="text/json" id="expected">
+{
+  "summarized_status": {
+    "status_string": "ERROR",
+    "message": "Error: Example Error"
+  },
+  "summarized_tests": [
+    {
+      "status_string": "NOTRUN",
+      "name": "This should show a harness status of 'Error' and a test status of 'Not Run'",
+      "properties": {},
+      "message": null
+    }
+  ],
+  "type": "complete"
+}
+</script>
+</body>
+</html>
diff --git a/test/wpt/tests/resources/test/tests/functional/uncaught-exception-ignore.html b/test/wpt/tests/resources/test/tests/functional/uncaught-exception-ignore.html
new file mode 100644
index 0000000..6bd0ddb
--- /dev/null
+++ b/test/wpt/tests/resources/test/tests/functional/uncaught-exception-ignore.html
@@ -0,0 +1,35 @@
+<!DOCTYPE HTML>
+<html>
+<head>
+<title>Harness Ignoring Uncaught Exception</title>
+</head>
+<script src="/resources/testharness.js"></script>
+
+<body>
+<h1>Harness Ignoring Uncaught Exception</h1>
+<div id="log"></div>
+<script>
+setup({allow_uncaught_exception:true});
+var t = async_test("setup({allow_uncaught_exception:true}) should allow tests to pass even if there is an exception");
+onerror = t.step_func(function() {t.done()});
+throw new Error("Example Error");
+</script>
+<script type="text/json" id="expected">
+{
+  "summarized_status": {
+    "status_string": "OK",
+    "message": null
+  },
+  "summarized_tests": [
+    {
+      "status_string": "PASS",
+      "name": "setup({allow_uncaught_exception:true}) should allow tests to pass even if there is an exception",
+      "properties": {},
+      "message": null
+    }
+  ],
+  "type": "complete"
+}
+</script>
+</body>
+</html>
diff --git a/test/wpt/tests/resources/test/tests/functional/worker-dedicated-uncaught-allow.html b/test/wpt/tests/resources/test/tests/functional/worker-dedicated-uncaught-allow.html
new file mode 100644
index 0000000..ba28d49
--- /dev/null
+++ b/test/wpt/tests/resources/test/tests/functional/worker-dedicated-uncaught-allow.html
@@ -0,0 +1,45 @@
+<!DOCTYPE HTML>
+<html>
+<head>
+<title>Dedicated Worker Tests - Allowed Uncaught Exception</title>
+<script src="/resources/testharness.js"></script>
+<script src="/resources/testharnessreport.js"></script>
+</head>
+<body>
+<h1>Dedicated Web Worker Tests - Allowed Uncaught Exception</h1>
+<p>Demonstrates running <tt>testharness</tt> based tests inside a dedicated web worker.
+<p>The test harness is expected to pass despite an uncaught exception in a worker because that worker is configured to allow uncaught exceptions.</p>
+<div id="log"></div>
+
+<script>
+test(function(t) {
+        assert_true("Worker" in self, "Browser should support Workers");
+    },
+    "Browser supports Workers");
+
+fetch_tests_from_worker(new Worker("worker-uncaught-allow.js"));
+</script>
+<script type="text/json" id="expected">
+{
+  "summarized_status": {
+    "status_string": "OK",
+    "message": null
+  },
+  "summarized_tests": [
+    {
+      "status_string": "PASS",
+      "name": "Browser supports Workers",
+      "properties": {},
+      "message": null
+    },
+    {
+      "status_string": "PASS",
+      "name": "onerror event is triggered",
+      "properties": {},
+      "message": null
+    }
+  ],
+  "type": "complete"
+}
+</script>
+</body>
diff --git a/test/wpt/tests/resources/test/tests/functional/worker-dedicated-uncaught-single.html b/test/wpt/tests/resources/test/tests/functional/worker-dedicated-uncaught-single.html
new file mode 100644
index 0000000..486e067
--- /dev/null
+++ b/test/wpt/tests/resources/test/tests/functional/worker-dedicated-uncaught-single.html
@@ -0,0 +1,56 @@
+<!DOCTYPE HTML>
+<html>
+<head>
+<title>Dedicated Worker Tests - Uncaught Exception in Single-Page Test</title>
+<script src="/resources/testharness.js"></script>
+<script src="/resources/testharnessreport.js"></script>
+</head>
+<body>
+<h1>Dedicated Web Worker Tests - Uncaught Exception in Single-Page Test</h1>
+<p>Demonstrates running <tt>testharness</tt> based tests inside a dedicated web worker.
+<p>The test harness is expected to pass despite an uncaught exception in a worker because that worker is a single-page test.</p>
+<div id="log"></div>
+
+<script>
+test(function(t) {
+        assert_true("Worker" in self, "Browser should support Workers");
+    },
+    "Browser supports Workers");
+
+fetch_tests_from_worker(new Worker("worker-uncaught-single.js"));
+
+test(function(t) {
+        assert_false(false, "False is false");
+    },
+    "Test running on main document.");
+</script>
+<script type="text/json" id="expected">
+{
+  "summarized_status": {
+    "status_string": "OK",
+    "message": null
+  },
+  "summarized_tests": [
+    {
+      "status_string": "PASS",
+      "name": "Browser supports Workers",
+      "properties": {},
+      "message": null
+    },
+    {
+      "status_string": "PASS",
+      "name": "Test running on main document.",
+      "properties": {},
+      "message": null
+    },
+    {
+      "status_string": "FAIL",
+      "name": "worker-uncaught-single",
+      "properties": {},
+      "message": "Error: This failure is expected."
+    }
+  ],
+  "type": "complete"
+}
+</script>
+</body>
diff --git a/test/wpt/tests/resources/test/tests/functional/worker-dedicated.sub.html b/test/wpt/tests/resources/test/tests/functional/worker-dedicated.sub.html
new file mode 100644
index 0000000..efd703c
--- /dev/null
+++ b/test/wpt/tests/resources/test/tests/functional/worker-dedicated.sub.html
@@ -0,0 +1,88 @@
+<!DOCTYPE HTML>
+<html>
+<head>
+<title>Dedicated Worker Tests</title>
+<script src="../../../testharness.js"></script>
+<script src="../../../testharnessreport.js"></script>
+</head>
+<body>
+<h1>Dedicated Web Worker Tests</h1>
+<p>Demonstrates running <tt>testharness</tt> based tests inside a dedicated web worker.
+<p>The test harness is expected to fail due to an uncaught exception in one worker.</p>
+<div id="log"></div>
+
+<script>
+test(function(t) {
+        assert_true("Worker" in self, "Browser should support Workers");
+    },
+    "Browser supports Workers");
+
+fetch_tests_from_worker(new Worker("worker.js"));
+
+fetch_tests_from_worker(new Worker("worker-error.js"));
+
+test(function(t) {
+        assert_false(false, "False is false");
+    },
+    "Test running on main document.");
+</script>
+<script type="text/json" id="expected">
+{
+  "summarized_status": {
+    "status_string": "ERROR",
+    "message": "Error: This failure is expected."
+  },
+  "summarized_tests": [
+    {
+      "status_string": "PASS",
+      "name": "Browser supports Workers",
+      "properties": {},
+      "message": null
+    },
+    {
+      "status_string": "PASS",
+      "name": "Test running on main document.",
+      "properties": {},
+      "message": null
+    },
+    {
+      "status_string": "PASS",
+      "name": "Worker async_test that completes successfully",
+      "properties": {},
+      "message": null
+    },
+    {
+      "status_string": "PASS",
+      "name": "Worker test that completes successfully",
+      "properties": {},
+      "message": null
+    },
+    {
+      "status_string": "PASS",
+      "name": "worker test that completes successfully before exception",
+      "properties": {},
+      "message": null
+    },
+    {
+      "status_string": "NOTRUN",
+      "name": "Worker test that doesn't run ('NOT RUN')",
+      "properties": {},
+      "message": null
+    },
+    {
+      "status_string": "FAIL",
+      "name": "Worker test that fails ('FAIL')",
+      "properties": {},
+      "message": "assert_true: Failing test expected true got false"
+    },
+    {
+      "status_string": "TIMEOUT",
+      "name": "Worker test that times out ('TIMEOUT')",
+      "properties": {},
+      "message": "Test timed out"
+    }
+  ],
+  "type": "complete"
+}
+</script>
+</body>
diff --git a/test/wpt/tests/resources/test/tests/functional/worker-error.js b/test/wpt/tests/resources/test/tests/functional/worker-error.js
new file mode 100644
index 0000000..7b89602
--- /dev/null
+++ b/test/wpt/tests/resources/test/tests/functional/worker-error.js
@@ -0,0 +1,8 @@
+importScripts("/resources/testharness.js");
+
+// The following sub-test ensures that the worker is not interpreted as a
+// single-page test.  The subsequent uncaught exception should therefore be
+// interpreted as a harness error rather than a single-page test failure.
+test(function() {}, "worker test that completes successfully before exception");
+
+throw new Error("This failure is expected.");
diff --git a/test/wpt/tests/resources/test/tests/functional/worker-service.html b/test/wpt/tests/resources/test/tests/functional/worker-service.html
new file mode 100644
index 0000000..2e07746
--- /dev/null
+++ b/test/wpt/tests/resources/test/tests/functional/worker-service.html
@@ -0,0 +1,115 @@
+<!DOCTYPE HTML>
+<html>
+<head>
+<title>Example with a service worker</title>
+<script src="/resources/testharness.js"></script>
+<script src="/resources/testharnessreport.js"></script>
+</head>
+<body>
+<h1>Service Worker Tests</h1>
+<p>Demonstrates running <tt>testharness</tt> based tests inside a service worker.
+<p>The test harness should time out due to one of the tests inside the worker timing out.
+<p>This test assumes that the browser supports <a href="http://www.w3.org/TR/service-workers/">ServiceWorkers</a>.
+<div id="log"></div>
+
+<script>
+test(
+    function(t) {
+        assert_true("serviceWorker" in navigator,
+                    "navigator.serviceWorker exists");
+    },
+    "Browser supports ServiceWorker");
+
+promise_test(
+    function() {
+        // Since the service worker registration could be in an indeterminate
+        // state (due to, for example, a previous test run failing), we start by
+        // unregstering our service worker and then registering it again.
+        var scope = "service-worker-scope";
+        var worker_url = "worker.js";
+
+        return navigator.serviceWorker.register(worker_url, {scope: scope})
+            .then(
+                function(registration) {
+                    return registration.unregister();
+                })
+            .then(
+                function() {
+                    return navigator.serviceWorker.register(worker_url, {scope: scope});
+                })
+            .then(
+                function(registration) {
+                    add_completion_callback(
+                        function() {
+                            registration.unregister();
+                        });
+
+                    return new Promise(
+                        function(resolve) {
+                            registration.addEventListener("updatefound",
+                                function() {
+                                    resolve(registration.installing);
+                                });
+                        });
+                })
+            .then(
+                function(worker) {
+                    fetch_tests_from_worker(worker);
+                });
+    },
+    "Register ServiceWorker");
+</script>
+<script type="text/json" id="expected">
+{
+  "summarized_status": {
+    "status_string": "TIMEOUT",
+    "message": null
+  },
+  "summarized_tests": [
+    {
+      "status_string": "PASS",
+      "name": "Browser supports ServiceWorker",
+      "properties": {},
+      "message": null
+    },
+    {
+      "status_string": "PASS",
+      "name": "Register ServiceWorker",
+      "properties": {},
+      "message": null
+    },
+    {
+      "status_string": "PASS",
+      "name": "Worker async_test that completes successfully",
+      "properties": {},
+      "message": null
+    },
+    {
+      "status_string": "PASS",
+      "name": "Worker test that completes successfully",
+      "properties": {},
+      "message": null
+    },
+    {
+      "status_string": "NOTRUN",
+      "name": "Worker test that doesn't run ('NOT RUN')",
+      "properties": {},
+      "message": null
+    },
+    {
+      "status_string": "FAIL",
+      "name": "Worker test that fails ('FAIL')",
+      "properties": {},
+      "message": "assert_true: Failing test expected true got false"
+    },
+    {
+      "status_string": "TIMEOUT",
+      "name": "Worker test that times out ('TIMEOUT')",
+      "properties": {},
+      "message": "Test timed out"
+    }
+  ],
+  "type": "complete"
+}
+</script>
+</body>
diff --git a/test/wpt/tests/resources/test/tests/functional/worker-shared.html b/test/wpt/tests/resources/test/tests/functional/worker-shared.html
new file mode 100644
index 0000000..e26f17d
--- /dev/null
+++ b/test/wpt/tests/resources/test/tests/functional/worker-shared.html
@@ -0,0 +1,73 @@
+<!DOCTYPE HTML>
+<html>
+<head>
+<title>Example with a shared worker</title>
+<script src="/resources/testharness.js"></script>
+<script src="/resources/testharnessreport.js"></script>
+</head>
+<body>
+<h1>Shared Web Worker Tests</h1>
+<p>Demonstrates running <tt>testharness</tt> based tests inside a shared worker.
+<p>The test harness should time out due to one of the tests in the worker timing out.
+<p>This test assumes that the browser supports <a href="http://www.w3.org/TR/workers/#shared-workers-and-the-sharedworker-interface">shared web workers</a>.
+<div id="log"></div>
+
+<script>
+test(
+    function(t) {
+        assert_true("SharedWorker" in self,
+                    "Browser should support SharedWorkers");
+    },
+    "Browser supports SharedWorkers");
+
+fetch_tests_from_worker(new SharedWorker("worker.js",
+                                         "My shared worker"));
+</script>
+<script type="text/json" id="expected">
+{
+  "summarized_status": {
+    "status_string": "TIMEOUT",
+    "message": null
+  },
+  "summarized_tests": [
+    {
+      "status_string": "PASS",
+      "name": "Browser supports SharedWorkers",
+      "properties": {},
+      "message": null
+    },
+    {
+      "message": null,
+      "name": "Worker async_test that completes successfully",
+      "properties": {},
+      "status_string": "PASS"
+    },
+    {
+      "message": null,
+      "name": "Worker test that completes successfully",
+      "properties": {},
+      "status_string": "PASS"
+    },
+    {
+      "message": null,
+      "name": "Worker test that doesn't run ('NOT RUN')",
+      "properties": {},
+      "status_string": "NOTRUN"
+    },
+    {
+      "message": "assert_true: Failing test expected true got false",
+      "name": "Worker test that fails ('FAIL')",
+      "properties": {},
+      "status_string": "FAIL"
+    },
+    {
+      "message": "Test timed out",
+      "name": "Worker test that times out ('TIMEOUT')",
+      "properties": {},
+      "status_string": "TIMEOUT"
+    }
+  ],
+  "type": "complete"
+}
+</script>
+</body>
diff --git a/test/wpt/tests/resources/test/tests/functional/worker-uncaught-allow.js b/test/wpt/tests/resources/test/tests/functional/worker-uncaught-allow.js
new file mode 100644
index 0000000..6925d59
--- /dev/null
+++ b/test/wpt/tests/resources/test/tests/functional/worker-uncaught-allow.js
@@ -0,0 +1,19 @@
+importScripts("/resources/testharness.js");
+
+setup({allow_uncaught_exception:true});
+
+async_test(function(t) {
+  onerror = function() {
+    // Further delay the test's completion to ensure that the worker's
+    // `onerror` handler does not influence results in the parent context.
+    setTimeout(function() {
+      t.done();
+    }, 0);
+  };
+
+  setTimeout(function() {
+    throw new Error("This error is expected.");
+  }, 0);
+}, 'onerror event is triggered');
+
+done();
diff --git a/test/wpt/tests/resources/test/tests/functional/worker-uncaught-single.js b/test/wpt/tests/resources/test/tests/functional/worker-uncaught-single.js
new file mode 100644
index 0000000..c04542b
--- /dev/null
+++ b/test/wpt/tests/resources/test/tests/functional/worker-uncaught-single.js
@@ -0,0 +1,8 @@
+importScripts("/resources/testharness.js");
+
+setup({ single_test: true });
+
+// Because this script enables the `single_test` configuration option, it
+// should be interpreted as a single-page test, and the uncaught exception
+// should be reported as a test failure (harness status: OK).
+throw new Error("This failure is expected.");
diff --git a/test/wpt/tests/resources/test/tests/functional/worker.js b/test/wpt/tests/resources/test/tests/functional/worker.js
new file mode 100644
index 0000000..a923bc2
--- /dev/null
+++ b/test/wpt/tests/resources/test/tests/functional/worker.js
@@ -0,0 +1,34 @@
+importScripts("/resources/testharness.js");
+
+test(
+    function(test) {
+        assert_true(true, "True is true");
+    },
+    "Worker test that completes successfully");
+
+test(
+    function(test) {
+        assert_true(false, "Failing test");
+    },
+    "Worker test that fails ('FAIL')");
+
+async_test(
+    function(test) {
+        assert_true(true, "True is true");
+    },
+    "Worker test that times out ('TIMEOUT')");
+
+async_test("Worker test that doesn't run ('NOT RUN')");
+
+async_test(
+    function(test) {
+        self.setTimeout(
+            function() {
+                test.done();
+            },
+            0);
+    },
+    "Worker async_test that completes successfully");
+
+// An explicit done() is required for dedicated and shared web workers.
+done();
diff --git a/test/wpt/tests/resources/test/tests/unit/IdlArray/is_json_type.html b/test/wpt/tests/resources/test/tests/unit/IdlArray/is_json_type.html
new file mode 100644
index 0000000..18e83a8
--- /dev/null
+++ b/test/wpt/tests/resources/test/tests/unit/IdlArray/is_json_type.html
@@ -0,0 +1,192 @@
+<!DOCTYPE HTML>
+<html>
+<head>
+<title>IdlArray.prototype.is_json_type()</title>
+</head>
+<body>
+<div id="log"></div>
+<script src="/resources/testharness.js"></script>
+<script src="/resources/testharnessreport.js"></script>
+<script src="/resources/WebIDLParser.js"></script>
+<script src="/resources/idlharness.js"></script>
+<script src="../../../idl-helper.js"></script>
+<script>
+    "use strict";
+
+    test(function() {
+        var idl = new IdlArray();
+        assert_true(idl.is_json_type(typeFrom("DOMString")));
+        assert_true(idl.is_json_type(typeFrom("ByteString")));
+        assert_true(idl.is_json_type(typeFrom("USVString")));
+        idl.add_untested_idls('enum BarEnum { "a", "b", "c" };');
+        assert_true(idl.is_json_type(typeFrom("BarEnum")));
+    }, 'should return true for all string types');
+
+    test(function() {
+        var idl = new IdlArray();
+        assert_false(idl.is_json_type(typeFrom("Error")));
+        assert_false(idl.is_json_type(typeFrom("DOMException")));
+    }, 'should return false for all exception types');
+
+    test(function() {
+        var idl = new IdlArray();
+        assert_false(idl.is_json_type(typeFrom("Int8Array")));
+        assert_false(idl.is_json_type(typeFrom("Int16Array")));
+        assert_false(idl.is_json_type(typeFrom("Int32Array")));
+        assert_false(idl.is_json_type(typeFrom("Uint8Array")));
+        assert_false(idl.is_json_type(typeFrom("Uint16Array")));
+        assert_false(idl.is_json_type(typeFrom("Uint32Array")));
+        assert_false(idl.is_json_type(typeFrom("Uint8ClampedArray")));
+        assert_false(idl.is_json_type(typeFrom("BigInt64Array")));
+        assert_false(idl.is_json_type(typeFrom("BigUint64Array")));
+        assert_false(idl.is_json_type(typeFrom("Float32Array")));
+        assert_false(idl.is_json_type(typeFrom("Float64Array")));
+        assert_false(idl.is_json_type(typeFrom("ArrayBuffer")));
+        assert_false(idl.is_json_type(typeFrom("DataView")));
+    }, 'should return false for all buffer source types');
+
+    test(function() {
+        var idl = new IdlArray();
+        assert_true(idl.is_json_type(typeFrom("boolean")));
+    }, 'should return true for boolean');
+
+    test(function() {
+        var idl = new IdlArray();
+        assert_true(idl.is_json_type(typeFrom("byte")));
+        assert_true(idl.is_json_type(typeFrom("octet")));
+        assert_true(idl.is_json_type(typeFrom("short")));
+        assert_true(idl.is_json_type(typeFrom("unsigned short")));
+        assert_true(idl.is_json_type(typeFrom("long")));
+        assert_true(idl.is_json_type(typeFrom("unsigned long")));
+        assert_true(idl.is_json_type(typeFrom("long long")));
+        assert_true(idl.is_json_type(typeFrom("unsigned long long")));
+        assert_true(idl.is_json_type(typeFrom("float")));
+        assert_true(idl.is_json_type(typeFrom("unrestricted float")));
+        assert_true(idl.is_json_type(typeFrom("double")));
+        assert_true(idl.is_json_type(typeFrom("unrestricted double")));
+    }, 'should return true for all numeric types');
+
+    test(function() {
+        var idl = new IdlArray();
+        assert_false(idl.is_json_type(typeFrom("Promise<DOMString>")));
+    }, 'should return false for promises');
+
+    test(function() {
+        var idl = new IdlArray();
+        assert_false(idl.is_json_type(typeFrom("sequence<DOMException>")));
+        assert_true(idl.is_json_type(typeFrom("sequence<DOMString>")));
+    }, 'should handle sequences according to their inner types');
+
+    test(function() {
+        var idl = new IdlArray();
+        assert_false(idl.is_json_type(typeFrom("FrozenArray<DOMException>")));
+        assert_true(idl.is_json_type(typeFrom("FrozenArray<DOMString>")));
+    }, 'should handle frozen arrays according to their inner types');
+
+    test(function() {
+        var idl = new IdlArray();
+        assert_true(idl.is_json_type(typeFrom("record<DOMString, DOMString>")));
+        assert_false(idl.is_json_type(typeFrom("record<DOMString, Error>")));
+    }, 'should handle records according to their inner types');
+
+    test(function() {
+        var idl = new IdlArray();
+        assert_true(idl.is_json_type(typeFrom("object")));
+    }, 'should return true for object type');
+
+    test(function() {
+        var idl = new IdlArray();
+        assert_false(idl.is_json_type(typeFrom("any")));
+    }, 'should return false for any type');
+
+    test(function() {
+        var idl = new IdlArray();
+        idl.add_untested_idls('dictionary Foo { DOMString foo; }; dictionary Bar : Foo { DOMString bar; };');
+        assert_true(idl.is_json_type(typeFrom("Foo")));
+        assert_true(idl.is_json_type(typeFrom("Bar")));
+    }, 'should return true for dictionaries whose members are all JSON types');
+
+    test(function() {
+        var idl = new IdlArray();
+        idl.add_untested_idls('dictionary Foo { };');
+        assert_true(idl.is_json_type(typeFrom("Foo")));
+    }, 'should return true for dictionaries which have no members');
+
+    test(function() {
+        var idl = new IdlArray();
+        idl.add_untested_idls('dictionary FooBar { DOMString a; Error b; }; dictionary Baz : FooBar {};');
+        assert_false(idl.is_json_type(typeFrom("FooBar")));
+        assert_false(idl.is_json_type(typeFrom("Baz")));
+    }, 'should return false for dictionaries whose members are not all JSON types');
+
+    test(function() {
+        var idl = new IdlArray();
+        idl.add_untested_idls('interface Foo { DOMString toJSON(); };');
+        assert_true(idl.is_json_type(typeFrom("Foo")));
+    }, 'should return true for interfaces which declare a toJSON operation');
+
+    test(function() {
+        var idl = new IdlArray();
+        idl.add_untested_idls('interface Foo { DOMString toJSON(); }; interface Bar : Foo { };');
+        assert_true(idl.is_json_type(typeFrom("Bar")));
+    }, 'should return true for interfaces which inherit from an interface which declares a toJSON operation');
+
+    test(function() {
+        var idl = new IdlArray();
+        idl.add_untested_idls('interface Foo { }; interface mixin Bar { DOMString toJSON(); }; Foo includes Bar;');
+        idl.merge_mixins();
+        assert_true(idl.is_json_type(typeFrom("Foo")));
+    }, 'should return true for interfaces which mixin an interface which declare a toJSON operation');
+
+    test(function() {
+        var idl = new IdlArray();
+        idl.add_untested_idls('interface Foo { };');
+        assert_false(idl.is_json_type(typeFrom("Foo")));
+    }, 'should return false for interfaces which do not declare a toJSON operation');
+
+    test(function() {
+        var idl = new IdlArray();
+        idl.add_untested_idls('interface Foo { object toJSON(); };');
+        assert_true(idl.is_json_type(typeFrom("(Foo or DOMString)")));
+    }, 'should return true for union types whose member types are JSON types');
+
+    test(function() {
+        var idl = new IdlArray();
+        assert_false(idl.is_json_type(typeFrom("(DataView or DOMString)")));
+    }, 'should return false for union types whose member types are not all JSON types');
+
+    test(function() {
+        var idl = new IdlArray();
+        assert_true(idl.is_json_type(typeFrom("DOMString?")));
+        assert_false(idl.is_json_type(typeFrom("DataView?")));
+    }, 'should consider the inner types of nullable types');
+
+    test(function() {
+        var idl = new IdlArray();
+        assert_true(idl.is_json_type(typeFrom("[XAttr] long")));
+        assert_false(idl.is_json_type(typeFrom("[XAttr] DataView")));
+    }, 'should consider the inner types of annotated types.');
+
+    test(function() {
+        var idl = new IdlArray();
+        assert_throws_js(Error, _ => idl.is_json_type(typeFrom("Foo")));
+    }, "should throw if it references a dictionary, enum or interface which wasn't added to the IdlArray");
+
+    test(function() {
+        var idl = new IdlArray();
+        idl.add_untested_idls('interface Foo : Bar { };');
+        assert_throws_js(Error, _ => idl.is_json_type(typeFrom("Foo")));
+    }, "should throw for interfaces which inherit from another interface which wasn't added to the IdlArray");
+
+    test(function() {
+        var idl = new IdlArray();
+        assert_true(idl.is_json_type(typedefFrom("typedef double DOMHighResTimeStamp;").idlType));
+    }, 'should return true for typedefs whose source type is a JSON type');
+
+    test(function() {
+        var idl = new IdlArray();
+        assert_false(idl.is_json_type(typedefFrom("typedef DataView DOMHighResTimeStamp;").idlType));
+    }, 'should return false for typedefs whose source type is not a JSON type');
+</script>
+</body>
+</html>
diff --git a/test/wpt/tests/resources/test/tests/unit/IdlDictionary/get_reverse_inheritance_stack.html b/test/wpt/tests/resources/test/tests/unit/IdlDictionary/get_reverse_inheritance_stack.html
new file mode 100644
index 0000000..418bcde
--- /dev/null
+++ b/test/wpt/tests/resources/test/tests/unit/IdlDictionary/get_reverse_inheritance_stack.html
@@ -0,0 +1,47 @@
+<!DOCTYPE HTML>
+<html>
+<head>
+<title>IdlDictionary.prototype.get_reverse_inheritance_stack()</title>
+</head>
+<body>
+<div id="log"></div>
+<script src="/resources/testharness.js"></script>
+<script src="/resources/testharnessreport.js"></script>
+<script src="/resources/WebIDLParser.js"></script>
+<script src="/resources/idlharness.js"></script>
+<script src="../../../idl-helper.js"></script>
+<script>
+    "use strict";
+    test(function() {
+        var stack = dictionaryFrom('dictionary A { };').get_reverse_inheritance_stack();
+        assert_array_equals(stack.map(d => d.name), ["A"]);
+    }, 'should return an array that includes itself.');
+
+    test(function() {
+        var d = dictionaryFrom('dictionary A : B { };');
+        assert_throws_js(Error, _ => d.get_reverse_inheritance_stack());
+    }, "should throw for dictionaries which inherit from another dictionary which wasn't added to the IdlArray");
+
+    test(function() {
+        var idl = new IdlArray();
+        idl.add_idls('dictionary A : B { };');
+        idl.add_untested_idls('dictionary B : C { }; dictionary C { };');
+        var A = idl.members["A"];
+        assert_array_equals(A.get_reverse_inheritance_stack().map(d => d.name), ["C", "B", "A"]);
+    }, 'should return an array of dictionaries in order of inheritance, starting with the base dictionary');
+
+    test(function () {
+      let i = new IdlArray();
+      i.add_untested_idls('dictionary A : B {};');
+      i.assert_throws(new IdlHarnessError('A inherits B, but B is undefined.'), i => i.test());
+    }, 'A : B with B undeclared should throw IdlHarnessError');
+
+    test(function () {
+      let i = new IdlArray();
+      i.add_untested_idls('dictionary A : B {};');
+      i.add_untested_idls('interface B {};');
+      i.assert_throws(new IdlHarnessError('A inherits B, but A is not an interface.'), i => i.test());
+    }, 'dictionary A : B with B interface should throw IdlHarnessError');
+</script>
+</body>
+</html>
diff --git a/test/wpt/tests/resources/test/tests/unit/IdlDictionary/test_partial_dictionary.html b/test/wpt/tests/resources/test/tests/unit/IdlDictionary/test_partial_dictionary.html
new file mode 100644
index 0000000..d6137f6
--- /dev/null
+++ b/test/wpt/tests/resources/test/tests/unit/IdlDictionary/test_partial_dictionary.html
@@ -0,0 +1,39 @@
+<!DOCTYPE HTML>
+<html>
+
+<head>
+  <meta charset="utf-8">
+  <title>idlharness: partial dictionaries</title>
+  <script src="/resources/testharness.js"></script>
+  <script src="/resources/testharnessreport.js"></script>
+  <script src="/resources/WebIDLParser.js"></script>
+  <script src="/resources/idlharness.js"></script>
+  <script src="../../../idl-helper.js"></script>
+</head>
+
+<body>
+<pre id='idl'>
+dictionary A {};
+partial dictionary A {
+  boolean B;
+};
+partial dictionary A {
+  boolean C;
+};
+</pre>
+
+<script>
+'use strict';
+
+test(() => {
+  let idlArray = new IdlArray();
+  idlArray.add_idls(document.getElementById('idl').textContent);
+  idlArray.test();
+
+  let members = idlArray.members["A"].members.map(m => m.name);
+  assert_array_equals(members, ["B", "C"], 'A should contain B, C');
+}, 'Partial dictionaries');
+</script>
+
+</body>
+</html>
diff --git a/test/wpt/tests/resources/test/tests/unit/IdlInterface/constructors.html b/test/wpt/tests/resources/test/tests/unit/IdlInterface/constructors.html
new file mode 100644
index 0000000..e9ee3f8
--- /dev/null
+++ b/test/wpt/tests/resources/test/tests/unit/IdlInterface/constructors.html
@@ -0,0 +1,26 @@
+<!DOCTYPE HTML>
+<title>IdlInterface.prototype.constructors()</title>
+<div id="log"></div>
+<script src="/resources/testharness.js"></script>
+<script src="/resources/testharnessreport.js"></script>
+<script src="/resources/WebIDLParser.js"></script>
+<script src="/resources/idlharness.js"></script>
+<script src="../../../idl-helper.js"></script>
+<script>
+"use strict";
+// [Constructor] extended attribute should not be supported:
+test(function() {
+    var i = interfaceFrom('[Constructor] interface A { };');
+    assert_equals(i.constructors().length, 0);
+}, 'Interface with Constructor extended attribute.');
+
+test(function() {
+    var i = interfaceFrom('interface A { constructor(); };');
+    assert_equals(i.constructors().length, 1);
+}, 'Interface with constructor method');
+
+test(function() {
+    var i = interfaceFrom('interface A { constructor(); constructor(any value); };');
+    assert_equals(i.constructors().length, 2);
+}, 'Interface with constructor overloads');
+</script>
diff --git a/test/wpt/tests/resources/test/tests/unit/IdlInterface/default_to_json_operation.html b/test/wpt/tests/resources/test/tests/unit/IdlInterface/default_to_json_operation.html
new file mode 100644
index 0000000..5ade7d0
--- /dev/null
+++ b/test/wpt/tests/resources/test/tests/unit/IdlInterface/default_to_json_operation.html
@@ -0,0 +1,114 @@
+<!DOCTYPE HTML>
+<html>
+<head>
+<title>IdlDictionary.prototype.default_to_json_operation()</title>
+</head>
+<body>
+<div id="log"></div>
+<script src="/resources/testharness.js"></script>
+<script src="/resources/testharnessreport.js"></script>
+<script src="/resources/WebIDLParser.js"></script>
+<script src="/resources/idlharness.js"></script>
+<script src="../../../idl-helper.js"></script>
+<script>
+    "use strict";
+    test(function() {
+        var map = interfaceFrom('interface A { [Default] object toJSON(); };').default_to_json_operation();
+        assert_equals(map.size, 0);
+    }, 'should return an empty map when there are no attributes');
+
+    test(function() {
+        var r = interfaceFrom('interface A { };').default_to_json_operation();
+        assert_equals(r, null);
+    }, 'should return null when there is no toJSON method');
+
+    test(function() {
+        var r = interfaceFrom('interface A { DOMString toJSON(); };').default_to_json_operation();
+        assert_equals(r, null);
+    }, 'should return null when there is a toJSON method but it does not have the [Default] extended attribute');
+
+    test(function() {
+        var context = new IdlArray();
+        context.add_idls("interface A : B { DOMString toJSON(); };");
+        context.add_idls("interface B { [Default] object toJSON(); };");
+        var r = context.members.A.default_to_json_operation();
+        assert_equals(r, null);
+    }, 'should return null when there is a toJSON method but it does not have the [Default] extended attribute even if this extended attribute exists on inherited interfaces');
+
+    test(function() {
+        var map = interfaceFrom('interface A { [Default] object toJSON(); static attribute DOMString foo; };').default_to_json_operation();
+        assert_equals(map.size, 0);
+    }, 'should not include static attributes');
+
+    test(function() {
+        var map = interfaceFrom('interface A { [Default] object toJSON(); attribute Promise<DOMString> bar; };').default_to_json_operation();
+        assert_equals(map.size, 0);
+    }, 'should not include attributes which are not JSON types');
+
+    test(function() {
+        var map = interfaceFrom('interface A { [Default] object toJSON(); DOMString bar(); };').default_to_json_operation();
+        assert_equals(map.size, 0);
+    }, 'should not include operations');
+
+    test(function() {
+        var map = interfaceFrom('interface A { [Default] object toJSON(); attribute DOMString bar; };').default_to_json_operation();
+        assert_equals(map.size, 1);
+        assert_true(map.has("bar"));
+        assert_equals(map.get("bar").idlType, "DOMString");
+    }, 'should return a map whose key/value pair represent the identifier and IDL type of valid attributes');
+
+    test(function() {
+        var context = new IdlArray();
+        context.add_idls("interface A : B { [Default] object toJSON(); attribute DOMString a; };");
+        context.add_idls("interface B { [Default] object toJSON(); attribute long b; };");
+        var map = context.members.A.default_to_json_operation();
+        assert_array_equals([...map.keys()], ["b", "a"]);
+        assert_array_equals([...map.values()].map(v => v.idlType), ["long", "DOMString"]);
+    }, 'should return a properly ordered map that contains IDL types of valid attributes for inherited interfaces');
+
+    test(function() {
+        var context = new IdlArray();
+        context.add_idls("interface A : B { attribute DOMString a; };");
+        context.add_idls("interface B { [Default] object toJSON(); attribute long b; };");
+        var map = context.members.A.default_to_json_operation();
+        assert_equals(map.size, 1);
+        assert_true(map.has("b"));
+        assert_equals(map.get("b").idlType, "long");
+        assert_array_equals([...map.keys()], ["b"]);
+    }, 'should not include attributes of the current interface when the [Default] toJSON method in inherited');
+
+    test(function() {
+        var context = new IdlArray();
+        context.add_idls("interface A : B { [Default] object toJSON(); };");
+        context.add_idls("interface B : C { [Default] object toJSON(); attribute DOMString foo; };");
+        context.add_idls("interface C { [Default] object toJSON(); attribute long foo; };");
+        var map = context.members.A.default_to_json_operation();
+        assert_equals(map.size, 1);
+        assert_true(map.has("foo"));
+        assert_equals(map.get("foo").idlType, "DOMString");
+    }, 'attributes declared further away in the inheritance hierarchy should be masked by attributes declared closer');
+
+    test(function() {
+        var context = new IdlArray();
+        context.add_idls("interface A { [Default] object toJSON(); attribute DOMString a; };");
+        context.add_idls("interface B : A { attribute any b; };");
+        context.add_idls("interface C : B { [Default] object toJSON(); attribute long c; };");
+        var map = context.members.C.default_to_json_operation();
+        assert_array_equals([...map.keys()], ["a", "c"]);
+        assert_array_equals([...map.values()].map(v => v.idlType), ["DOMString", "long"]);
+    }, 'should return an ordered map that ignores attributes of inherited interfaces which do not declare a [Default] toJSON operation.');
+
+    test(function() {
+        var context = new IdlArray();
+        context.add_idls("interface D { attribute DOMString d; };");
+        context.add_idls("interface mixin M { [Default] object toJSON(); attribute long m; };");
+        context.add_idls("D includes M;");
+        context.merge_mixins();
+        var map = context.members.D.default_to_json_operation();
+        assert_array_equals([...map.keys()], ["d", "m"]);
+        assert_array_equals([...map.values()].map(v => v.idlType), ["DOMString", "long"]);
+    }, 'should return a properly ordered map that accounts for mixed-in interfaces which declare a [Default] toJSON operation.');
+</script>
+</body>
+</html>
+
diff --git a/test/wpt/tests/resources/test/tests/unit/IdlInterface/do_member_unscopable_asserts.html b/test/wpt/tests/resources/test/tests/unit/IdlInterface/do_member_unscopable_asserts.html
new file mode 100644
index 0000000..90142ef
--- /dev/null
+++ b/test/wpt/tests/resources/test/tests/unit/IdlInterface/do_member_unscopable_asserts.html
@@ -0,0 +1,56 @@
+<!DOCTYPE HTML>
+<html>
+<head>
+<title>IdlDictionary.prototype.do_member_unscopable_asserts()</title>
+</head>
+<body>
+<div id="log"></div>
+<script src="/resources/testharness.js"></script>
+<script src="/resources/testharnessreport.js"></script>
+<script src="/resources/WebIDLParser.js"></script>
+<script src="/resources/idlharness.js"></script>
+<script src="../../../idl-helper.js"></script>
+<script>
+    'use strict';
+    function mock_interface_A(unscopables) {
+        self.A = function A() {};
+        A.prototype[Symbol.unscopables] = unscopables;
+    }
+
+    test(function() {
+        const i = interfaceFrom('interface A { [Unscopable] attribute any x; };');
+        const member = i.members[0];
+        assert_true(member.isUnscopable);
+        mock_interface_A({ x: true });
+        i.do_member_unscopable_asserts(member);
+    }, 'should not throw for [Unscopable] with property in @@unscopables');
+
+    test(function() {
+        const i = interfaceFrom('interface A { [Unscopable] attribute any x; };');
+        const member = i.members[0];
+        assert_true(member.isUnscopable);
+        mock_interface_A({});
+        // assert_throws_* can't be used because they rethrow AssertionErrors.
+        try {
+            i.do_member_unscopable_asserts(member);
+        } catch(e) {
+            assert_true(e.message.includes('Symbol.unscopables'));
+            return;
+        }
+        assert_unreached('did not throw');
+    }, 'should throw for [Unscopable] with property missing from @@unscopables');
+
+    // This test checks that for attributes/methods which aren't [Unscopable]
+    // in the IDL, we don't assert that @@unscopables is missing the property.
+    // This could miss implementation bugs, but [Unscopable] is so rarely used
+    // that it's fairly unlikely to ever happen.
+    test(function() {
+        const i = interfaceFrom('interface A { attribute any x; };');
+        const member = i.members[0];
+        assert_false(member.isUnscopable);
+        mock_interface_A({ x: true });
+        i.do_member_unscopable_asserts(member);
+    }, 'should not throw if [Unscopable] is used but property is in @@unscopables');
+</script>
+</body>
+</html>
diff --git a/test/wpt/tests/resources/test/tests/unit/IdlInterface/get_interface_object.html b/test/wpt/tests/resources/test/tests/unit/IdlInterface/get_interface_object.html
new file mode 100644
index 0000000..a3d901a
--- /dev/null
+++ b/test/wpt/tests/resources/test/tests/unit/IdlInterface/get_interface_object.html
@@ -0,0 +1,22 @@
+<!DOCTYPE HTML>
+<title>IdlInterface.prototype.get_interface_object()</title>
+<div id="log"></div>
+<script src="/resources/testharness.js"></script>
+<script src="/resources/testharnessreport.js"></script>
+<script src="/resources/WebIDLParser.js"></script>
+<script src="/resources/idlharness.js"></script>
+<script src="../../../idl-helper.js"></script>
+<script>
+"use strict";
+test(function() {
+    window.A = {};
+    var i = interfaceFrom('interface A { };');
+    assert_equals(i.get_interface_object(), window.A);
+}, 'Interface does not have LegacyNamespace.');
+
+test(function() {
+    window.Foo = { A: {} };
+    var i = interfaceFrom('[LegacyNamespace=Foo] interface A { }; namespace Foo { };');
+    assert_equals(i.get_interface_object(), window.Foo.A);
+}, 'Interface has LegacyNamespace');
+</script>
diff --git a/test/wpt/tests/resources/test/tests/unit/IdlInterface/get_interface_object_owner.html b/test/wpt/tests/resources/test/tests/unit/IdlInterface/get_interface_object_owner.html
new file mode 100644
index 0000000..51ab206
--- /dev/null
+++ b/test/wpt/tests/resources/test/tests/unit/IdlInterface/get_interface_object_owner.html
@@ -0,0 +1,21 @@
+<!DOCTYPE HTML>
+<title>IdlInterface.prototype.get_interface_object_owner()</title>
+<div id="log"></div>
+<script src="/resources/testharness.js"></script>
+<script src="/resources/testharnessreport.js"></script>
+<script src="/resources/WebIDLParser.js"></script>
+<script src="/resources/idlharness.js"></script>
+<script src="../../../idl-helper.js"></script>
+<script>
+"use strict";
+test(function() {
+    var i = interfaceFrom('interface A { };');
+    assert_equals(i.get_interface_object_owner(), window);
+}, 'Interface does not have LegacyNamespace.');
+
+test(function() {
+    window.Foo = {};
+    var i = interfaceFrom('[LegacyNamespace=Foo] interface A { }; namespace Foo { };');
+    assert_equals(i.get_interface_object_owner(), window.Foo);
+}, 'Interface has LegacyNamespace');
+</script>
diff --git a/test/wpt/tests/resources/test/tests/unit/IdlInterface/get_legacy_namespace.html b/test/wpt/tests/resources/test/tests/unit/IdlInterface/get_legacy_namespace.html
new file mode 100644
index 0000000..e2d42bb
--- /dev/null
+++ b/test/wpt/tests/resources/test/tests/unit/IdlInterface/get_legacy_namespace.html
@@ -0,0 +1,20 @@
+<!DOCTYPE HTML>
+<title>IdlInterface.prototype.get_legacy_namespace()</title>
+<div id="log"></div>
+<script src="/resources/testharness.js"></script>
+<script src="/resources/testharnessreport.js"></script>
+<script src="/resources/WebIDLParser.js"></script>
+<script src="/resources/idlharness.js"></script>
+<script src="../../../idl-helper.js"></script>
+<script>
+"use strict";
+test(function() {
+    var i = interfaceFrom('interface A { };');
+    assert_equals(i.get_legacy_namespace(), undefined);
+}, 'Interface does not have LegacyNamespace.');
+
+test(function() {
+    var i = interfaceFrom('[LegacyNamespace=Foo] interface A { }; namespace Foo { };');
+    assert_equals(i.get_legacy_namespace(), "Foo");
+}, 'Interface has LegacyNamespace');
+</script>
diff --git a/test/wpt/tests/resources/test/tests/unit/IdlInterface/get_qualified_name.html b/test/wpt/tests/resources/test/tests/unit/IdlInterface/get_qualified_name.html
new file mode 100644
index 0000000..677a31b
--- /dev/null
+++ b/test/wpt/tests/resources/test/tests/unit/IdlInterface/get_qualified_name.html
@@ -0,0 +1,20 @@
+<!DOCTYPE HTML>
+<title>IdlInterface.prototype.get_qualified_name()</title>
+<div id="log"></div>
+<script src="/resources/testharness.js"></script>
+<script src="/resources/testharnessreport.js"></script>
+<script src="/resources/WebIDLParser.js"></script>
+<script src="/resources/idlharness.js"></script>
+<script src="../../../idl-helper.js"></script>
+<script>
+"use strict";
+test(function() {
+    var i = interfaceFrom('interface A { };');
+    assert_equals(i.get_qualified_name(), "A");
+}, 'Interface does not have LegacyNamespace.');
+
+test(function() {
+    var i = interfaceFrom('[LegacyNamespace=Foo] interface A { }; namespace Foo { };');
+    assert_equals(i.get_qualified_name(), "Foo.A");
+}, 'Interface has LegacyNamespace');
+</script>
diff --git a/test/wpt/tests/resources/test/tests/unit/IdlInterface/get_reverse_inheritance_stack.html b/test/wpt/tests/resources/test/tests/unit/IdlInterface/get_reverse_inheritance_stack.html
new file mode 100644
index 0000000..0c066ba
--- /dev/null
+++ b/test/wpt/tests/resources/test/tests/unit/IdlInterface/get_reverse_inheritance_stack.html
@@ -0,0 +1,49 @@
+<!DOCTYPE HTML>
+<html>
+<head>
+<title>IdlInterface.prototype.get_reverse_inheritance_stack()</title>
+</head>
+<body>
+<div id="log"></div>
+<script src="/resources/testharness.js"></script>
+<script src="/resources/testharnessreport.js"></script>
+<script src="/resources/WebIDLParser.js"></script>
+<script src="/resources/idlharness.js"></script>
+<script src="../../../idl-helper.js"></script>
+<script>
+    "use strict";
+    test(function() {
+        var stack = interfaceFrom('interface A { };').get_reverse_inheritance_stack();
+        assert_array_equals(stack.map(i => i.name), ["A"]);
+    }, 'should return an array that includes itself.');
+
+    test(function() {
+        var i = interfaceFrom('interface A : B { };');
+        assert_throws_js(Error, _ => i.get_reverse_inheritance_stack());
+    }, "should throw for interfaces which inherit from another interface which wasn't added to the IdlArray");
+
+    test(function() {
+        var idl = new IdlArray();
+        idl.add_idls('interface A : B { };');
+        idl.add_untested_idls('interface B : C { }; interface C { };');
+        var A = idl.members["A"];
+        assert_array_equals(A.get_reverse_inheritance_stack().map(i => i.name), ["C", "B", "A"]);
+    }, 'should return an array of interfaces in order of inheritance, starting with the base interface');
+
+    test(function () {
+        var idl = new IdlArray();
+        idl.add_untested_idls('interface A : B { };');
+        idl.add_untested_idls('interface B : A { };');
+        idl.assert_throws('A has a circular dependency: A,B,A', i => i.test());
+    }, 'should throw when inheritance is circular');
+
+    test(function () {
+        var idl = new IdlArray();
+        idl.add_untested_idls('interface A : B { };');
+        idl.assert_throws(
+            'Duplicate identifier A',
+            i => i.add_untested_idls('interface A : C { };'));
+    }, 'should throw when multiple inheritances defined');
+</script>
+</body>
+</html>
diff --git a/test/wpt/tests/resources/test/tests/unit/IdlInterface/has_default_to_json_regular_operation.html b/test/wpt/tests/resources/test/tests/unit/IdlInterface/has_default_to_json_regular_operation.html
new file mode 100644
index 0000000..b47262b
--- /dev/null
+++ b/test/wpt/tests/resources/test/tests/unit/IdlInterface/has_default_to_json_regular_operation.html
@@ -0,0 +1,47 @@
+<!DOCTYPE HTML>
+<html>
+<head>
+<title>IdlInterface.prototype.has_default_to_json_regular_operation()</title>
+</head>
+<body>
+<div id="log"></div>
+<script src="/resources/testharness.js"></script>
+<script src="/resources/testharnessreport.js"></script>
+<script src="/resources/WebIDLParser.js"></script>
+<script src="/resources/idlharness.js"></script>
+<script src="../../../idl-helper.js"></script>
+<script>
+    "use strict";
+    test(function() {
+        var i = interfaceFrom('interface A { };');
+        assert_false(i.has_default_to_json_regular_operation());
+    }, 'should return false when the interface declares no toJSON operation.');
+
+    test(function() {
+        var i = interfaceFrom('interface A { static object toJSON(); };');
+        assert_false(i.has_default_to_json_regular_operation());
+    }, 'should return false when the interface declares a static toJSON operation.');
+
+    test(function() {
+        var i = interfaceFrom('interface A { object toJSON(); };');
+        assert_false(i.has_default_to_json_regular_operation());
+    }, 'should return false when the interface declares a regular toJSON operation with no extended attribute.');
+
+    test(function() {
+        var i = interfaceFrom('interface A { [x] object toJSON(); };');
+        assert_false(i.has_default_to_json_regular_operation());
+    }, 'should return false when the interface declares a regular toJSON operation with another extented attribute.');
+
+    test(function() {
+        var i = interfaceFrom('interface A { [Default] object toJSON(); };');
+        assert_true(i.has_default_to_json_regular_operation());
+    }, 'should return true when the interface declares a regular toJSON operation with the [Default] extented attribute.');
+
+    test(function() {
+        var i = interfaceFrom('interface A { [Attr, AnotherAttr, Default] object toJSON(); };');
+        assert_true(i.has_default_to_json_regular_operation());
+    }, 'should return true when the interface declares a regular toJSON operation with multiple extended attributes, including [Default].');
+</script>
+</body>
+</html>
+
diff --git a/test/wpt/tests/resources/test/tests/unit/IdlInterface/has_to_json_regular_operation.html b/test/wpt/tests/resources/test/tests/unit/IdlInterface/has_to_json_regular_operation.html
new file mode 100644
index 0000000..a1a641b
--- /dev/null
+++ b/test/wpt/tests/resources/test/tests/unit/IdlInterface/has_to_json_regular_operation.html
@@ -0,0 +1,31 @@
+<!DOCTYPE HTML>
+<html>
+<head>
+<title>IdlInterface.prototype.has_to_json_regular_operation()</title>
+</head>
+<body>
+<div id="log"></div>
+<script src="/resources/testharness.js"></script>
+<script src="/resources/testharnessreport.js"></script>
+<script src="/resources/WebIDLParser.js"></script>
+<script src="/resources/idlharness.js"></script>
+<script src="../../../idl-helper.js"></script>
+<script>
+    "use strict";
+    test(function() {
+        var i = interfaceFrom('interface A { };');
+        assert_false(i.has_to_json_regular_operation());
+    }, 'should return false when the interface declares no toJSON operation.');
+
+    test(function() {
+        var i = interfaceFrom('interface A { static object toJSON(); };');
+        assert_false(i.has_to_json_regular_operation());
+    }, 'should return false when the interface declares a static toJSON operation.');
+
+    test(function() {
+        var i = interfaceFrom('interface A { object toJSON(); };');
+        assert_true(i.has_to_json_regular_operation());
+    }, 'should return true when the interface declares a regular toJSON operation.');
+</script>
+</body>
+</html>
diff --git a/test/wpt/tests/resources/test/tests/unit/IdlInterface/should_have_interface_object.html b/test/wpt/tests/resources/test/tests/unit/IdlInterface/should_have_interface_object.html
new file mode 100644
index 0000000..3ce9457
--- /dev/null
+++ b/test/wpt/tests/resources/test/tests/unit/IdlInterface/should_have_interface_object.html
@@ -0,0 +1,30 @@
+<!DOCTYPE HTML>
+<title>IdlInterface.prototype.should_have_interface_object()</title>
+<div id="log"></div>
+<script src="/resources/testharness.js"></script>
+<script src="/resources/testharnessreport.js"></script>
+<script src="/resources/WebIDLParser.js"></script>
+<script src="/resources/idlharness.js"></script>
+<script src="../../../idl-helper.js"></script>
+<script>
+"use strict";
+test(function() {
+    var i = interfaceFrom("callback interface A { const unsigned short B = 0; };");
+    assert_true(i.should_have_interface_object());
+}, "callback interface with a constant");
+
+test(function() {
+    var i = interfaceFrom("callback interface A { undefined b(); sequence<any> c(); };");
+    assert_false(i.should_have_interface_object());
+}, "callback interface without a constant");
+
+test(function() {
+    var i = interfaceFrom("[LegacyNoInterfaceObject] interface A { };");
+    assert_false(i.should_have_interface_object());
+}, "non-callback interface with [LegacyNoInterfaceObject]");
+
+test(function() {
+    var i = interfaceFrom("interface A { };");
+    assert_true(i.should_have_interface_object());
+}, "non-callback interface without [LegacyNoInterfaceObject]");
+</script>
diff --git a/test/wpt/tests/resources/test/tests/unit/IdlInterface/test_primary_interface_of_undefined.html b/test/wpt/tests/resources/test/tests/unit/IdlInterface/test_primary_interface_of_undefined.html
new file mode 100644
index 0000000..0031558
--- /dev/null
+++ b/test/wpt/tests/resources/test/tests/unit/IdlInterface/test_primary_interface_of_undefined.html
@@ -0,0 +1,29 @@
+<!DOCTYPE HTML>
+<html>
+
+<head>
+  <title>idlharness test_primary_interface_of_undefined</title>
+</head>
+
+<body>
+  <script src="/resources/testharness.js"></script>
+  <script src="/resources/WebIDLParser.js"></script>
+  <script src="/resources/idlharness.js"></script>
+  <script>
+    'use strict';
+    test(function () {
+      let i = new IdlArray();
+      i.add_untested_idls('interface A : B {};');
+      i.assert_throws(new IdlHarnessError('A inherits B, but B is undefined.'), i => i.test());
+    }, 'A : B with B undeclared should throw IdlHarnessError');
+
+    test(function () {
+      let i = new IdlArray();
+      i.add_untested_idls('interface A : B {};');
+      i.add_untested_idls('dictionary B {};');
+      i.assert_throws(new IdlHarnessError('A inherits B, but B is not an interface.'), i => i.test());
+    }, 'interface A : B with B dictionary should throw IdlHarnessError');
+  </script>
+</body>
+
+</html>
diff --git a/test/wpt/tests/resources/test/tests/unit/IdlInterfaceMember/is_to_json_regular_operation.html b/test/wpt/tests/resources/test/tests/unit/IdlInterfaceMember/is_to_json_regular_operation.html
new file mode 100644
index 0000000..b3f402d
--- /dev/null
+++ b/test/wpt/tests/resources/test/tests/unit/IdlInterfaceMember/is_to_json_regular_operation.html
@@ -0,0 +1,42 @@
+<!DOCTYPE HTML>
+<html>
+<head>
+<title>IdlInterfaceMember.prototype.is_to_json_regular_operation()</title>
+</head>
+<body>
+<div id="log"></div>
+<script src="/resources/testharness.js"></script>
+<script src="/resources/testharnessreport.js"></script>
+<script src="/resources/WebIDLParser.js"></script>
+<script src="/resources/idlharness.js"></script>
+<script src="../../../idl-helper.js"></script>
+<script>
+    "use strict";
+    test(function() {
+        var m = memberFrom("readonly attribute DOMString foo");
+        assert_false(m.is_to_json_regular_operation());
+    }, 'should return false when member is an attribute.');
+
+    test(function() {
+        var m = memberFrom("static undefined foo()");
+        assert_false(m.is_to_json_regular_operation());
+    }, 'should return false when member is a static operation.');
+
+    test(function() {
+        var m = memberFrom("static object toJSON()");
+        assert_false(m.is_to_json_regular_operation());
+    }, 'should return false when member is a static toJSON operation.');
+
+    test(function() {
+        var m = memberFrom("object toJSON()");
+        assert_true(m.is_to_json_regular_operation());
+    }, 'should return true when member is a regular toJSON operation.');
+
+    test(function() {
+        var m = memberFrom("[Foo] object toJSON()");
+        assert_true(m.is_to_json_regular_operation());
+    }, 'should return true when member is a regular toJSON operation with extensible attributes.');
+</script>
+</body>
+</html>
+
diff --git a/test/wpt/tests/resources/test/tests/unit/IdlInterfaceMember/toString.html b/test/wpt/tests/resources/test/tests/unit/IdlInterfaceMember/toString.html
new file mode 100644
index 0000000..054dbb1
--- /dev/null
+++ b/test/wpt/tests/resources/test/tests/unit/IdlInterfaceMember/toString.html
@@ -0,0 +1,36 @@
+<!DOCTYPE HTML>
+<html>
+<head>
+<title>IdlInterfaceMember.prototype.toString()</title>
+</head>
+<body>
+<div id="log"></div>
+<script src="/resources/testharness.js"></script>
+<script src="/resources/testharnessreport.js"></script>
+<script src="/resources/WebIDLParser.js"></script>
+<script src="/resources/idlharness.js"></script>
+<script src="../../../idl-helper.js"></script>
+<script>
+"use strict";
+const tests = [
+    ["long x", "long"],
+    ["long? x", "long?"],
+    ["Promise<long> x", "Promise<long>"],
+    ["Promise<long?> x", "Promise<long?>"],
+    ["sequence<long> x", "sequence<long>"],
+    ["(long or DOMString) x", "(long or DOMString)"],
+    ["long x, boolean y", "long, boolean"],
+    ["long x, optional boolean y", "long, optional boolean"],
+    ["long... args", "long..."],
+    ["sequence<long>... args", "sequence<long>..."],
+    ["(long or DOMString)... args", "(long or DOMString)..."],
+];
+for (const [input, output] of tests) {
+    test(function() {
+        var m = memberFrom(`undefined foo(${input})`);
+        assert_equals(m.toString(), `foo(${output})`);
+    }, `toString for ${input}`);
+}
+</script>
+</body>
+</html>
diff --git a/test/wpt/tests/resources/test/tests/unit/assert_implements.html b/test/wpt/tests/resources/test/tests/unit/assert_implements.html
new file mode 100644
index 0000000..6e35f38
--- /dev/null
+++ b/test/wpt/tests/resources/test/tests/unit/assert_implements.html
@@ -0,0 +1,43 @@
+<!DOCTYPE HTML>
+<html lang="en">
+<meta charset="utf-8">
+<script src="/resources/testharness.js"></script>
+<script src="/resources/testharnessreport.js"></script>
+<script src="/resources/test/tests/unit/helpers.js"></script>
+<title>assert_implements unittests</title>
+<script>
+'use strict';
+
+test(() => {
+  // All values in JS that are not falsy are truthy, so we just check some
+  // common cases here.
+  assert_implements(true, 'true is a truthy value');
+  assert_implements(5, 'positive integeter is a truthy value');
+  assert_implements(-5, 'negative integeter is a truthy value');
+  assert_implements('foo', 'non-empty string is a truthy value');
+}, 'truthy values');
+
+test_failure(() => {
+  assert_implements(false);
+}, 'false is a falsy value');
+
+test_failure(() => {
+  assert_implements(0);
+}, '0 is a falsy value');
+
+test_failure(() => {
+  assert_implements('');
+}, 'empty string is a falsy value');
+
+test_failure(() => {
+  assert_implements(null);
+}, 'null is a falsy value');
+
+test_failure(() => {
+  assert_implements(undefined);
+}, 'undefined is a falsy value');
+
+test_failure(() => {
+  assert_implements(NaN);
+}, 'NaN is a falsy value');
+</script>
diff --git a/test/wpt/tests/resources/test/tests/unit/assert_implements_optional.html b/test/wpt/tests/resources/test/tests/unit/assert_implements_optional.html
new file mode 100644
index 0000000..4f23e20
--- /dev/null
+++ b/test/wpt/tests/resources/test/tests/unit/assert_implements_optional.html
@@ -0,0 +1,43 @@
+<!DOCTYPE HTML>
+<html lang="en">
+<meta charset="utf-8">
+<script src="/resources/testharness.js"></script>
+<script src="/resources/testharnessreport.js"></script>
+<script src="/resources/test/tests/unit/helpers.js"></script>
+<title>assert_implements_optional unittests</title>
+<script>
+'use strict';
+
+test(() => {
+  // All values in JS that are not falsy are truthy, so we just check some
+  // common cases here.
+  assert_implements_optional(true, 'true is a truthy value');
+  assert_implements_optional(5, 'positive integeter is a truthy value');
+  assert_implements_optional(-5, 'negative integeter is a truthy value');
+  assert_implements_optional('foo', 'non-empty string is a truthy value');
+}, 'truthy values');
+
+test_failure(() => {
+  assert_implements_optional(false);
+}, 'false is a falsy value');
+
+test_failure(() => {
+  assert_implements_optional(0);
+}, '0 is a falsy value');
+
+test_failure(() => {
+  assert_implements_optional('');
+}, 'empty string is a falsy value');
+
+test_failure(() => {
+  assert_implements_optional(null);
+}, 'null is a falsy value');
+
+test_failure(() => {
+  assert_implements_optional(undefined);
+}, 'undefined is a falsy value');
+
+test_failure(() => {
+  assert_implements_optional(NaN);
+}, 'NaN is a falsy value');
+</script>
diff --git a/test/wpt/tests/resources/test/tests/unit/assert_object_equals.html b/test/wpt/tests/resources/test/tests/unit/assert_object_equals.html
new file mode 100644
index 0000000..313d77b
--- /dev/null
+++ b/test/wpt/tests/resources/test/tests/unit/assert_object_equals.html
@@ -0,0 +1,152 @@
+<!DOCTYPE HTML>
+<html lang="en">
+<meta charset="utf-8">
+<script src="/resources/testharness.js"></script>
+<script src="/resources/testharnessreport.js"></script>
+<script src="/resources/test/tests/unit/helpers.js"></script>
+<title>Assertion functions</title>
+<script>
+'use strict';
+
+test(function() {
+  assert_object_equals({}, {});
+}, 'empty objects');
+
+test(function() {
+  var actual = {};
+  var expected = {};
+  actual.a = actual;
+  expected.a = actual;
+
+  assert_object_equals(actual, expected);
+}, 'tolerates cycles in actual value');
+
+test(function() {
+  var actual = {};
+  var expected = {};
+  actual.a = expected;
+  expected.a = expected;
+
+  assert_object_equals(actual, expected);
+}, 'tolerates cycles in expected value');
+
+test(function() {
+  assert_object_equals({2: 99, 0: 23, 1: 45}, [23, 45, 99]);
+}, 'recognizes equivalence of actual object and expected array');
+
+test(function() {
+  assert_object_equals([23, 45, 99], {2: 99, 0: 23, 1: 45});
+}, 'recognizes equivalence of actual array and expected object');
+
+test(function() {
+  var actual = {};
+  var expected = {};
+  Object.defineProperty(actual, 'a', { value: 1, enumerable: false });
+
+  assert_not_equals(actual.a, expected.a);
+  assert_object_equals(actual, expected);
+}, 'non-enumerable properties in actual value ignored');
+
+test(function() {
+  var actual = {};
+  var expected = {};
+  Object.defineProperty(expected, 'a', { value: 1, enumerable: false });
+
+  assert_not_equals(actual.a, expected.a);
+  assert_object_equals(actual, expected);
+}, 'non-enumerable properties in expected value ignored');
+
+test(function() {
+  assert_object_equals({c: 3, a: 1, b: 2}, {a: 1, b: 2, c: 3});
+}, 'equivalent objects - "flat" object');
+
+test(function() {
+  assert_object_equals(
+    {c: {e: 5, d: 4}, b: 2, a: 1},
+    {a: 1, b: 2, c: {d: 4, e: 5}}
+  );
+}, 'equivalent objects - nested object');
+
+test(function() {
+  assert_object_equals(
+    {c: [4, 5], b: 2, a: 1},
+    {a: 1, b: 2, c: [4, 5]}
+  );
+}, 'equivalent objects - nested array');
+
+test(function() {
+  assert_object_equals({a: NaN}, {a: NaN});
+}, 'equivalent objects - NaN value');
+
+test(function() {
+  assert_object_equals({a: -0}, {a: -0});
+}, 'equivalent objects - negative zero value');
+
+test_failure(function() {
+  assert_object_equals(undefined, {});
+}, 'invalid actual value: undefined');
+
+test_failure(function() {
+  assert_object_equals(null, {});
+}, 'invalid actual value: null');
+
+test_failure(function() {
+  assert_object_equals(34, {});
+}, 'invalid actual value: number');
+
+test_failure(function() {
+  assert_object_equals({c: 3, a: 1, b: 2}, {a: 1, b: 1, c: 3});
+}, 'unequal property value - "flat" object');
+
+test_failure(function() {
+  var actual = Object.create({a: undefined});
+  var expected = {};
+
+  assert_object_equals(actual, expected);
+}, 'non-own properties in actual value verified');
+
+test_failure(function() {
+  var actual = {};
+  var expected = Object.create({a: undefined});
+
+  assert_object_equals(actual, expected);
+}, 'non-own properties in expected value verified');
+
+test_failure(function() {
+  assert_object_equals(
+    {a: 1, b: 2, c: {d: 5, e: 5, f: 6}},
+    {a: 1, b: 2, c: {d: 5, e: 7, f: 6}}
+  );
+}, 'unequal property value - nested object');
+
+test_failure(function() {
+  assert_object_equals(
+    {a: 1, b: 2, c: [4, 5, 6]},
+    {a: 1, b: 2, c: [4, 7, 6]}
+  );
+}, 'unequal property value - nested array');
+
+test_failure(function() {
+  assert_object_equals({a: NaN}, {a: 0});
+}, 'equivalent objects - NaN actual value');
+
+test_failure(function() {
+  assert_object_equals({a: 0}, {a: NaN});
+}, 'equivalent objects - NaN expected value');
+
+test_failure(function() {
+  assert_object_equals({a: -0}, {a: 0});
+}, 'equivalent objects - negative zero actual value');
+
+test_failure(function() {
+  assert_object_equals({a: 0}, {a: -0});
+}, 'equivalent objects - negative zero expected value');
+
+test_failure(function() {
+  assert_object_equals({a: 1}, {});
+}, 'actual contains additional property');
+
+test_failure(function() {
+  assert_object_equals({}, {a: 1});
+}, 'expected contains additional property');
+</script>
diff --git a/test/wpt/tests/resources/test/tests/unit/async-test-return-restrictions.html b/test/wpt/tests/resources/test/tests/unit/async-test-return-restrictions.html
new file mode 100644
index 0000000..0fde2e2
--- /dev/null
+++ b/test/wpt/tests/resources/test/tests/unit/async-test-return-restrictions.html
@@ -0,0 +1,135 @@
+<!DOCTYPE HTML>
+<html>
+<head>
+  <meta charset="utf-8">
+  <script src="/resources/testharness.js"></script>
+  <title>Restrictions on return value from `async_test`</title>
+</head>
+<body>
+<script>
+function makeTest(...bodies) {
+  const closeScript = '<' + '/script>';
+  let src = `
+<!DOCTYPE HTML>
+<html>
+<head>
+<title>Document title</title>
+<script src="/resources/testharness.js?${Math.random()}">${closeScript}
+</head>
+
+<body>
+<div id="log"></div>`;
+  bodies.forEach((body) => {
+    src += '<script>(' + body + ')();' + closeScript;
+  });
+
+  const iframe = document.createElement('iframe');
+
+  document.body.appendChild(iframe);
+  iframe.contentDocument.write(src);
+
+  return new Promise((resolve) => {
+    window.addEventListener('message', function onMessage(e) {
+      if (e.source !== iframe.contentWindow) {
+        return;
+      }
+      if (!e.data || e.data.type !=='complete') {
+        return;
+      }
+      window.removeEventListener('message', onMessage);
+      resolve(e.data);
+    });
+
+    iframe.contentDocument.close();
+  }).then(({ tests, status }) => {
+    const summary = {
+      harness: {
+        status: getEnumProp(status, status.status),
+        message: status.message
+      },
+      tests: {}
+    };
+
+    tests.forEach((test) => {
+      summary.tests[test.name] = getEnumProp(test, test.status);
+    });
+
+    return summary;
+  });
+}
+
+function getEnumProp(object, value) {
+  for (let property in object) {
+    if (!/^[A-Z]+$/.test(property)) {
+      continue;
+    }
+
+    if (object[property] === value) {
+      return property;
+    }
+  }
+}
+
+promise_test(() => {
+  return makeTest(
+      () => {
+        async_test((t) => {t.done(); return undefined;}, 'before');
+        async_test((t) => {t.done(); return null;}, 'null');
+        async_test((t) => {t.done(); return undefined;}, 'after');
+      }
+    ).then(({harness, tests}) => {
+      assert_equals(harness.status, 'ERROR');
+      assert_equals(
+        harness.message,
+        'Test named "null" passed a function to `async_test` that returned a value.'
+      );
+      assert_equals(tests.before, 'PASS');
+      assert_equals(tests.null, 'PASS');
+      // This test did not get the chance to start.
+      assert_equals(tests.after, undefined);
+    });
+}, 'test returning `null`');
+
+promise_test(() => {
+  return makeTest(
+      () => {
+        async_test((t) => {t.done(); return undefined;}, 'before');
+        async_test((t) => {t.done(); return {};}, 'object');
+        async_test((t) => {t.done(); return undefined;}, 'after');
+      }
+    ).then(({harness, tests}) => {
+      assert_equals(harness.status, 'ERROR');
+      assert_equals(
+        harness.message,
+        'Test named "object" passed a function to `async_test` that returned a value.'
+      );
+      assert_equals(tests.before, 'PASS');
+      assert_equals(tests.object, 'PASS');
+      // This test did not get the chance to start.
+      assert_equals(tests.after, undefined);
+    });
+}, 'test returning an ordinary object');
+
+promise_test(() => {
+  return makeTest(
+      () => {
+        async_test((t) => {t.done(); return undefined;}, 'before');
+        async_test((t) => {t.done(); return Promise.resolve(5);}, 'thenable');
+        async_test((t) => {t.done(); return undefined;}, 'after');
+      }
+    ).then(({harness, tests}) => {
+      assert_equals(harness.status, 'ERROR');
+      assert_equals(
+        harness.message,
+        'Test named "thenable" passed a function to `async_test` that returned a value. ' +
+        'Consider using `promise_test` instead when using Promises or async/await.'
+      );
+      assert_equals(tests.before, 'PASS');
+      assert_equals(tests.thenable, 'PASS');
+      // This test did not get a chance to start.
+      assert_equals(tests.after, undefined);
+    });
+}, 'test returning a thenable object');
+</script>
+</body>
+</html>
diff --git a/test/wpt/tests/resources/test/tests/unit/basic.html b/test/wpt/tests/resources/test/tests/unit/basic.html
new file mode 100644
index 0000000..d52082f
--- /dev/null
+++ b/test/wpt/tests/resources/test/tests/unit/basic.html
@@ -0,0 +1,48 @@
+<!DOCTYPE HTML>
+<html>
+<head>
+<title>idlharness basic</title>
+</head>
+<body>
+<div id="log"></div>
+<script src="/resources/testharness.js"></script>
+<script src="/resources/testharnessreport.js"></script>
+<script src="/resources/WebIDLParser.js"></script>
+<script src="/resources/idlharness.js"></script>
+<script>
+    "use strict";
+    test(function() {
+        assert_true("IdlArray" in window);
+    }, 'IdlArray constructor should be a global object');
+    test(function() {
+        assert_true(new IdlArray() instanceof IdlArray);
+    }, 'IdlArray constructor should be constructible');
+    test(function() {
+        assert_true("WebIDL2" in window);
+    }, 'WebIDL2 namespace should be a global object');
+    test(function() {
+        assert_equals(typeof WebIDL2.parse, "function");
+    }, 'WebIDL2 namespace should have a parse method');
+    test(function() {
+        try {
+            WebIDL2.parse("I'm a syntax error");
+            throw new Error("Web IDL didn't throw");
+        } catch (e) {
+            assert_equals(e.name, "WebIDLParseError");
+        }
+    }, 'WebIDL2 parse method should bail on incorrect WebIDL');
+    test(function() {
+        assert_equals(typeof WebIDL2.parse("interface Foo {};"), "object");
+    }, 'WebIDL2 parse method should produce an AST for correct WebIDL');
+    test(function () {
+        try {
+            let i = new IdlArray();
+            i.add_untested_idls(`interface C {};`);
+            i.assert_throws('Anything', i => i.test());
+        } catch (e) {
+            assert_true(e instanceof IdlHarnessError);
+        }
+    }, `assert_throws should throw if no IdlHarnessError thrown`);
+</script>
+</body>
+</html>
diff --git a/test/wpt/tests/resources/test/tests/unit/exceptional-cases-timeouts.html b/test/wpt/tests/resources/test/tests/unit/exceptional-cases-timeouts.html
new file mode 100644
index 0000000..760ac71
--- /dev/null
+++ b/test/wpt/tests/resources/test/tests/unit/exceptional-cases-timeouts.html
@@ -0,0 +1,120 @@
+<!DOCTYPE HTML>
+<html>
+<head>
+  <meta charset="utf-8">
+  <meta name="timeout" content="long">
+  <script src="/resources/testharness.js"></script>
+  <title>Exceptional cases - timeouts</title>
+</head>
+<body>
+<p>
+  The tests in this file are executed in parallel to avoid exceeding the "long"
+  timeout duration.
+</p>
+<script>
+function makeTest(...bodies) {
+  const closeScript = '<' + '/script>';
+  let src = `
+<!DOCTYPE HTML>
+<html>
+<head>
+<title>Document title</title>
+<script src="/resources/testharness.js?${Math.random()}">${closeScript}
+</head>
+
+<body>
+<div id="log"></div>`;
+  bodies.forEach((body) => {
+    src += '<script>(' + body + ')();' + closeScript;
+  });
+
+  const iframe = document.createElement('iframe');
+
+  document.body.appendChild(iframe);
+  iframe.contentDocument.write(src);
+
+  return new Promise((resolve) => {
+    window.addEventListener('message', function onMessage(e) {
+      if (e.source !== iframe.contentWindow) {
+        return;
+      }
+      if (!e.data || e.data.type !=='complete') {
+        return;
+      }
+      window.removeEventListener('message', onMessage);
+      resolve(e.data);
+    });
+
+    iframe.contentDocument.close();
+  }).then(({ tests, status }) => {
+    const summary = {
+      harness: getEnumProp(status, status.status),
+      tests: {}
+    };
+
+    tests.forEach((test) => {
+      summary.tests[test.name] = getEnumProp(test, test.status);
+    });
+
+    return summary;
+  });
+}
+
+function getEnumProp(object, value) {
+  for (let property in object) {
+    if (!/^[A-Z]+$/.test(property)) {
+      continue;
+    }
+
+    if (object[property] === value) {
+      return property;
+    }
+  }
+}
+
+(() => {
+  window.asyncTestCleanupCount1 = 0;
+  const nestedTest = makeTest(
+    () => {
+      async_test((t) => {
+        t.add_cleanup(() => window.parent.asyncTestCleanupCount1 += 1);
+        setTimeout(() => {
+          throw new Error('this error is expected');
+        });
+      }, 'test');
+    }
+  );
+  promise_test(() => {
+    return nestedTest.then(({harness, tests}) => {
+        assert_equals(harness, 'ERROR');
+        assert_equals(tests.test, 'TIMEOUT');
+        assert_equals(window.asyncTestCleanupCount1, 1);
+      });
+  }, 'uncaught exception during async_test which times out');
+})();
+
+(() => {
+  window.promiseTestCleanupCount2 = 0;
+  const nestedTest = makeTest(
+    () => {
+      promise_test((t) => {
+        t.add_cleanup(() => window.parent.promiseTestCleanupCount2 += 1);
+        setTimeout(() => {
+          throw new Error('this error is expected');
+        });
+
+        return new Promise(() => {});
+      }, 'test');
+    }
+  );
+  promise_test(() => {
+    return nestedTest.then(({harness, tests}) => {
+        assert_equals(harness, 'ERROR');
+        assert_equals(tests.test, 'TIMEOUT');
+        assert_equals(window.promiseTestCleanupCount2, 1);
+      });
+  }, 'uncaught exception during promise_test which times out');
+})();
+</script>
+</body>
+</html>
diff --git a/test/wpt/tests/resources/test/tests/unit/exceptional-cases.html b/test/wpt/tests/resources/test/tests/unit/exceptional-cases.html
new file mode 100644
index 0000000..4054d03
--- /dev/null
+++ b/test/wpt/tests/resources/test/tests/unit/exceptional-cases.html
@@ -0,0 +1,392 @@
+<!DOCTYPE HTML>
+<html>
+<head>
+  <meta charset="utf-8">
+  <meta name="timeout" content="long">
+  <script src="/resources/testharness.js"></script>
+  <title>Exceptional cases</title>
+</head>
+<body>
+<script>
+function makeTest(...bodies) {
+  const closeScript = '<' + '/script>';
+  let src = `
+<!DOCTYPE HTML>
+<html>
+<head>
+<title>Document title</title>
+<script src="/resources/testharness.js?${Math.random()}">${closeScript}
+</head>
+
+<body>
+<div id="log"></div>`;
+  bodies.forEach((body) => {
+    src += '<script>(' + body + ')();' + closeScript;
+  });
+
+  const iframe = document.createElement('iframe');
+
+  document.body.appendChild(iframe);
+  iframe.contentDocument.write(src);
+
+  return new Promise((resolve) => {
+    window.addEventListener('message', function onMessage(e) {
+      if (e.source !== iframe.contentWindow) {
+        return;
+      }
+      if (!e.data || e.data.type !=='complete') {
+        return;
+      }
+      window.removeEventListener('message', onMessage);
+      resolve(e.data);
+    });
+
+    iframe.contentDocument.close();
+  }).then(({ tests, status }) => {
+    const summary = {
+      harness: getEnumProp(status, status.status),
+      tests: {}
+    };
+
+    tests.forEach((test) => {
+      summary.tests[test.name] = getEnumProp(test, test.status);
+    });
+
+    return summary;
+  });
+}
+
+function getEnumProp(object, value) {
+  for (let property in object) {
+    if (!/^[A-Z]+$/.test(property)) {
+      continue;
+    }
+
+    if (object[property] === value) {
+      return property;
+    }
+  }
+}
+
+promise_test(() => {
+  return makeTest(
+      () => { done(); }
+    ).then(({harness, tests}) => {
+      assert_equals(harness, 'ERROR');
+      assert_array_equals(Object.keys(tests), []);
+    });
+}, 'completion signaled before testing begins');
+
+promise_test(() => {
+  return makeTest(
+      () => { assert_true(true); done(); }
+    ).then(({harness, tests}) => {
+      assert_equals(harness, 'ERROR');
+      assert_array_equals(Object.keys(tests), []);
+    });
+}, 'passing assertion before testing begins');
+
+promise_test(() => {
+  return makeTest(
+      () => { assert_false(true); }
+    ).then(({harness, tests}) => {
+      assert_equals(harness, 'ERROR');
+      assert_array_equals(Object.keys(tests), []);
+    });
+}, 'failing assertion before testing begins');
+
+promise_test(() => {
+  return makeTest(
+      () => { throw new Error('this error is expected'); }
+    ).then(({harness, tests}) => {
+      assert_equals(harness, 'ERROR');
+      assert_array_equals(Object.keys(tests), []);
+    });
+}, 'uncaught exception before testing begins');
+
+promise_test(() => {
+  return makeTest(
+      () => {
+        setup({ allow_uncaught_exception: true });
+        throw new Error('this error is expected');
+      },
+      () => {
+        test(function() {}, 'a');
+        test(function() {}, 'b');
+      }
+    ).then(({harness, tests}) => {
+      assert_equals(harness, 'OK');
+      assert_equals(tests.a, 'PASS');
+      assert_equals(tests.b, 'PASS');
+    });
+}, 'uncaught exception with subsequent subtest');
+
+promise_test(() => {
+  return makeTest(
+      () => {
+        async_test((t) => {
+          setTimeout(() => {
+            setTimeout(() => t.done(), 0);
+            async_test((t) => { setTimeout(t.done.bind(t), 0); }, 'after');
+            throw new Error('this error is expected');
+          }, 0);
+        }, 'during');
+      }
+    ).then(({harness, tests}) => {
+      assert_equals(harness, 'ERROR');
+      assert_equals(tests.during, 'PASS');
+      assert_equals(tests.after, 'PASS');
+    });
+}, 'uncaught exception during async_test');
+
+promise_test(() => {
+  return makeTest(
+      () => {
+        promise_test(() => {
+          return new Promise((resolve) => {
+            setTimeout(() => {
+              resolve();
+              promise_test(() => Promise.resolve(), 'after');
+              throw new Error('this error is expected');
+            }, 0);
+          });
+        }, 'during');
+      }
+    ).then(({harness, tests}) => {
+      assert_equals(harness, 'ERROR');
+      assert_equals(tests.during, 'PASS');
+      assert_equals(tests.after, 'PASS');
+    });
+}, 'uncaught exception during promise_test');
+
+promise_test(() => {
+  return makeTest(
+      () => { test(() => {}, 'before'); },
+      () => { throw new Error('this error is expected'); },
+      () => { test(() => {}, 'after'); }
+    ).then(({harness, tests}) => {
+      assert_equals(harness, 'ERROR');
+      assert_equals(tests.before, 'PASS');
+      assert_equals(tests.after, 'PASS');
+    });
+}, 'uncaught exception between tests');
+
+promise_test(() => {
+  return makeTest(
+      () => { promise_test(() => Promise.resolve(), 'before'); },
+      () => { throw new Error('this error is expected'); },
+      () => { promise_test(() => Promise.resolve(), 'after'); }
+    ).then(({harness, tests}) => {
+      assert_equals(harness, 'ERROR');
+      assert_equals(tests.before, 'PASS');
+      assert_equals(tests.after, 'PASS');
+    });
+}, 'uncaught exception between promise_tests');
+
+
+// This feature of testharness.js is only observable in browsers which
+// implement the `unhandledrejection` event.
+if ('onunhandledrejection' in window) {
+
+  promise_test(() => {
+    return makeTest(
+        () => { Promise.reject(new Error('this error is expected')); }
+      ).then(({harness, tests}) => {
+        assert_equals(harness, 'ERROR');
+        assert_array_equals(Object.keys(tests), []);
+      });
+  }, 'unhandled rejection before testing begins');
+
+  promise_test(() => {
+    return makeTest(
+        () => {
+          async_test((t) => {
+            Promise.reject(new Error('this error is expected'));
+
+            window.addEventListener('unhandledrejection', () => {
+            setTimeout(() => t.done(), 0);
+              async_test((t) => { setTimeout(t.done.bind(t), 0); }, 'after');
+              t.done();
+            });
+          }, 'during');
+        }
+      ).then(({harness, tests}) => {
+        assert_equals(harness, 'ERROR');
+        assert_equals(tests.during, 'PASS');
+        assert_equals(tests.after, 'PASS');
+      });
+  }, 'unhandled rejection during async_test');
+
+  promise_test(() => {
+    return makeTest(
+        () => {
+          promise_test(() => {
+            return new Promise((resolve) => {
+              Promise.reject(new Error('this error is expected'));
+
+              window.addEventListener('unhandledrejection', () => {
+                resolve();
+                promise_test(() => Promise.resolve(), 'after');
+                throw new Error('this error is expected');
+              }, 0);
+            });
+          }, 'during');
+        }
+      ).then(({harness, tests}) => {
+        assert_equals(harness, 'ERROR');
+        assert_equals(tests.during, 'PASS');
+        assert_equals(tests.after, 'PASS');
+      });
+  }, 'unhandled rejection during promise_test');
+
+  promise_test(() => {
+    return makeTest(
+        () => {
+          setup({ explicit_done: true });
+          test(() => {}, 'before');
+          Promise.reject(new Error('this error is expected'));
+          window.addEventListener('unhandledrejection', () => {
+            test(() => {}, 'after');
+            done();
+          });
+        }
+      ).then(({harness, tests}) => {
+        assert_equals(harness, 'ERROR');
+        assert_equals(tests.before, 'PASS');
+        assert_true('after' in tests);
+      });
+  }, 'unhandled rejection between tests');
+
+  promise_test(() => {
+    return makeTest(
+        () => {
+          setup({ explicit_done: true });
+          async_test((t) => { setTimeout(t.done.bind(t), 0); }, 'before');
+          Promise.reject(new Error('this error is expected'));
+          window.addEventListener('unhandledrejection', () => {
+            async_test((t) => { setTimeout(t.done.bind(t), 0); }, 'after');
+            done();
+          });
+        }
+      ).then(({harness, tests}) => {
+        assert_equals(harness, 'ERROR');
+        assert_equals(tests.before, 'PASS');
+        assert_equals(tests.after, 'PASS');
+      });
+  }, 'unhandled rejection between async_tests');
+
+  promise_test(() => {
+    return makeTest(
+        () => {
+          setup({ explicit_done: true });
+          promise_test(() => Promise.resolve(), 'before');
+          Promise.reject(new Error('this error is expected'));
+          window.addEventListener('unhandledrejection', () => {
+            promise_test(() => Promise.resolve(), 'after');
+            done();
+          });
+        }
+      ).then(({harness, tests}) => {
+        assert_equals(harness, 'ERROR');
+        assert_equals(tests.before, 'PASS');
+        assert_true('after' in tests);
+      });
+  }, 'unhandled rejection between promise_tests');
+
+  promise_test(() => {
+    return makeTest(
+        () => {
+          test((t) => {
+            t.add_cleanup(() => { throw new Error('this error is expected'); });
+          }, 'during');
+          test((t) => {}, 'after');
+        }
+      ).then(({harness, tests}) => {
+        assert_equals(harness, 'ERROR');
+        assert_equals(tests.during, 'PASS');
+        assert_equals(tests.after, 'NOTRUN');
+      });
+  }, 'exception in `add_cleanup` of a test');
+
+}
+
+
+promise_test(() => {
+  return makeTest(
+      () => {
+        setup({explicit_done: true});
+        window.addEventListener('DOMContentLoaded', () => {
+          async_test((t) => {
+            t.add_cleanup(() => {
+              setTimeout(() => {
+                async_test((t) => t.done(), 'after');
+                done();
+              }, 0);
+              throw new Error('this error is expected');
+            });
+            setTimeout(t.done.bind(t), 0);
+          }, 'during');
+        });
+      }
+    ).then(({harness, tests}) => {
+      assert_equals(harness, 'ERROR');
+      assert_equals(tests.during, 'PASS');
+      assert_equals(tests.after, 'NOTRUN');
+    });
+}, 'exception in `add_cleanup` of an async_test');
+
+promise_test(() => {
+  return makeTest(
+      () => {
+        promise_test((t) => {
+          t.add_cleanup(() => { throw new Error('this error is expected'); });
+          return Promise.resolve();
+        }, 'test');
+      }
+    ).then(({harness, tests}) => {
+      assert_equals(harness, 'ERROR');
+      assert_equals(tests.test, 'PASS');
+    });
+}, 'exception in `add_cleanup` of a promise_test');
+
+promise_test(() => {
+  return makeTest(
+      () => {
+        promise_test((t) => {
+          t.step(() => {
+            throw new Error('this error is expected');
+          });
+        }, 'test');
+        async_test((t) => t.done(), 'after');
+      }
+    ).then(({harness, tests}) => {
+      assert_equals(harness, 'OK');
+      assert_equals(tests.test, 'FAIL');
+      assert_equals(tests.after, 'PASS');
+    });
+}, 'exception in `step` of an async_test');
+
+promise_test(() => {
+  return makeTest(
+      () => {
+        promise_test((t) => {
+          t.step(() => {
+            throw new Error('this error is expected');
+          });
+
+          return new Promise(() => {});
+        }, 'test');
+
+        // This following test should be run to completion despite the fact
+        // that the promise returned by the previous test never resolves.
+        promise_test((t) => Promise.resolve(), 'after');
+      }
+    ).then(({harness, tests}) => {
+      assert_equals(harness, 'OK');
+      assert_equals(tests.test, 'FAIL');
+      assert_equals(tests.after, 'PASS');
+    });
+}, 'exception in `step` of a promise_test');
+</script>
+</body>
+</html>
diff --git a/test/wpt/tests/resources/test/tests/unit/format-value.html b/test/wpt/tests/resources/test/tests/unit/format-value.html
new file mode 100644
index 0000000..13d01b8
--- /dev/null
+++ b/test/wpt/tests/resources/test/tests/unit/format-value.html
@@ -0,0 +1,123 @@
+<!DOCTYPE HTML>
+<html>
+<head>
+  <title>format_value utility function</title>
+  <meta charset="utf-8">
+</head>
+<body>
+<div id="log"></div>
+<script src="/resources/testharness.js"></script>
+<script src="/resources/testharnessreport.js"></script>
+<script>
+"use strict";
+
+test(function() {
+  assert_equals(format_value(null), "null");
+}, "null");
+
+test(function() {
+  assert_equals(format_value(undefined), "undefined");
+}, "undefined");
+
+test(function() {
+  assert_equals(format_value(true), "true");
+  assert_equals(format_value(false), "false");
+}, "boolean values");
+
+test(function() {
+  assert_equals(format_value(0.4), "0.4");
+  assert_equals(format_value(0), "0");
+  assert_equals(format_value(-0), "-0");
+}, "number values");
+
+test(function() {
+  assert_equals(format_value("a string"), "\"a string\"");
+  assert_equals(format_value("new\nline"), "\"new\\nline\"");
+}, "string values");
+
+test(function() {
+  var node = document.createElement("span");
+  node.setAttribute("data-foo", "bar");
+  assert_true(
+    /<span\b/i.test(format_value(node)), "element includes tag name"
+  );
+  assert_true(
+    /data-foo=["']?bar["']?/i.test(format_value(node)),
+    "element includes attributes"
+  );
+}, "node value: element node");
+
+test(function() {
+  var text = document.createTextNode("wpt");
+  assert_equals(format_value(text), "Text node \"wpt\"");
+}, "node value: text node");
+
+test(function() {
+  var node = document.createProcessingInstruction("wpt1", "wpt2");
+  assert_equals(
+    format_value(node),
+    "ProcessingInstruction node with target \"wpt1\" and data \"wpt2\""
+  );
+}, "node value: ProcessingInstruction node");
+
+test(function() {
+  var node = document.createComment("wpt");
+  assert_equals(format_value(node), "Comment node <!--wpt-->");
+}, "node value: comment node");
+
+test(function() {
+  var node = document.implementation.createDocument(
+    "application/xhtml+xml", "", null
+  );
+
+  assert_equals(format_value(node), "Document node with 0 children");
+
+  node.appendChild(document.createElement('html'));
+
+  assert_equals(format_value(node), "Document node with 1 child");
+}, "node value: document node");
+
+test(function() {
+  var node = document.implementation.createDocumentType("foo", "baz", "baz");
+
+  assert_equals(format_value(node), "DocumentType node");
+}, "node value: DocumentType node");
+
+test(function() {
+  var node = document.createDocumentFragment();
+
+  assert_equals(format_value(node), "DocumentFragment node with 0 children");
+
+  node.appendChild(document.createElement("span"));
+
+  assert_equals(format_value(node), "DocumentFragment node with 1 child");
+
+  node.appendChild(document.createElement("span"));
+
+  assert_equals(format_value(node), "DocumentFragment node with 2 children");
+}, "node value: DocumentFragment node");
+
+test(function() {
+  assert_equals(format_value(Symbol("wpt")), "symbol \"Symbol(wpt)\"");
+}, "symbol value");
+
+test(function() {
+ assert_equals(format_value([]), "[]");
+ assert_equals(format_value(["one"]), "[\"one\"]");
+ assert_equals(format_value(["one", "two"]), "[\"one\", \"two\"]");
+}, "array values");
+
+test(function() {
+  var obj = {
+    toString: function() {
+      throw "wpt";
+    }
+  };
+
+  assert_equals(
+    format_value(obj), "[stringifying object threw wpt with type string]"
+  );
+}, "object value with faulty `toString`");
+</script>
+</body>
+</html>
diff --git a/test/wpt/tests/resources/test/tests/unit/helpers.js b/test/wpt/tests/resources/test/tests/unit/helpers.js
new file mode 100644
index 0000000..ca378a2
--- /dev/null
+++ b/test/wpt/tests/resources/test/tests/unit/helpers.js
@@ -0,0 +1,21 @@
+// Helper for testing assertion failure cases for a testharness.js API
+//
+// The `assert_throws_*` functions cannot be used for this purpose because they
+// always fail in response to AssertionError exceptions, even when this is
+// expressed as the expected error.
+function test_failure(fn, name) {
+  test(function() {
+    try {
+      fn();
+    } catch (err) {
+      if (err instanceof AssertionError) {
+        return;
+      }
+      throw new AssertionError('Expected an AssertionError, but' + err);
+    }
+    throw new AssertionError(
+      'Expected an AssertionError, but no error was thrown'
+    );
+  }, name);
+}
+
diff --git a/test/wpt/tests/resources/test/tests/unit/late-test.html b/test/wpt/tests/resources/test/tests/unit/late-test.html
new file mode 100644
index 0000000..693d7e3
--- /dev/null
+++ b/test/wpt/tests/resources/test/tests/unit/late-test.html
@@ -0,0 +1,54 @@
+<!DOCTYPE HTML>
+<html>
+<head>
+<title>Test declared after harness completion</title>
+</head>
+<body>
+<div id="log"></div>
+<script src="/resources/testharness.js"></script>
+<script src="/resources/testharnessreport.js"></script>
+<p>This test simulates an automated test running scenario, where the test
+results emitted by testharness.js may be interpreted after some delay. It is
+intended to demonstrate that in such cases, any additional tests which are
+executed during that delay are <em>not</em> included in the dataset.</p>
+
+<p>Although these "late" tests are likely an indication of a mistake in test
+design, they cannot be detected deterministically, so in the interest of
+stability, they should be silently tolerated.</p>
+<script>
+async_test(function(t) {
+    var source = [
+        "<div id='log'></div>",
+        "<script src='/resources/testharness.js'></" + "script>",
+        "<script src='/resources/testharnessreport.js'></" + "script>",
+        "<script>",
+        "parent.childReady(window);",
+        "setup({ explicit_done: true });",
+        "test(function() {}, 'acceptable test');",
+        "onload = function() {",
+        "  done();",
+        "  test(function() {}, 'this test is late and should be ignored');",
+        "};",
+        "</" + "script>"
+    ].join("\n");
+    var iframe = document.createElement("iframe");
+
+    document.body.appendChild(iframe);
+    window.childReady = t.step_func(function(childWindow) {
+        childWindow.add_completion_callback(t.step_func(function(tests, status) {
+            t.step_timeout(t.step_func(function() {
+                assert_equals(tests.length, 1);
+                assert_equals(tests[0].name, "acceptable test");
+                assert_equals(status.status, status.OK);
+                t.done();
+            }), 0);
+        }));
+    });
+
+    iframe.contentDocument.open();
+    iframe.contentDocument.write(source);
+    iframe.contentDocument.close();
+});
+</script>
+</body>
+</html>
diff --git a/test/wpt/tests/resources/test/tests/unit/promise_setup-timeout.html b/test/wpt/tests/resources/test/tests/unit/promise_setup-timeout.html
new file mode 100644
index 0000000..c4947fe
--- /dev/null
+++ b/test/wpt/tests/resources/test/tests/unit/promise_setup-timeout.html
@@ -0,0 +1,28 @@
+<!DOCTYPE HTML>
+<html>
+<head>
+  <meta charset="utf-8">
+  <meta name="timeout" content="long">
+  <script src="/resources/testharness.js"></script>
+  <script src="../../nested-testharness.js"></script>
+  <title>promise_setup - timeout</title>
+</head>
+<body>
+<script>
+'use strict';
+promise_test(() => {
+  return makeTest(
+      () => {
+        test(() => {}, 'before');
+        promise_setup(() => new Promise(() => {}));
+        promise_test(() => Promise.resolve(), 'after');
+      }
+    ).then(({harness, tests}) => {
+      assert_equals(harness, 'TIMEOUT');
+      assert_equals(tests.before, 'PASS');
+      assert_equals(tests.after, 'NOTRUN');
+    });
+}, 'timeout when returned promise does not settle');
+</script>
+</body>
+</html>
diff --git a/test/wpt/tests/resources/test/tests/unit/promise_setup.html b/test/wpt/tests/resources/test/tests/unit/promise_setup.html
new file mode 100644
index 0000000..2abb10a
--- /dev/null
+++ b/test/wpt/tests/resources/test/tests/unit/promise_setup.html
@@ -0,0 +1,333 @@
+<!DOCTYPE HTML>
+<html>
+<head>
+  <meta charset="utf-8">
+  <script src="/resources/testharness.js"></script>
+  <script src="../../nested-testharness.js"></script>
+  <title>promise_setup</title>
+</head>
+<body>
+<script>
+'use strict';
+promise_test(() => {
+  return makeTest(
+      () => {
+        // Ensure that the harness error is the result of explicit error
+        // handling
+        setup({ allow_uncaught_exception: true });
+
+        test(() => {}, 'before');
+        promise_setup({});
+        promise_test(() => Promise.resolve(), 'after');
+      }
+    ).then(({harness, tests}) => {
+      assert_equals(harness, 'ERROR');
+      assert_equals(tests.before, 'PASS');
+      assert_equals(tests.after, undefined);
+    });
+}, 'Error when no function provided');
+
+promise_test(() => {
+  return makeTest(
+      () => {
+        test(() => {}, 'before');
+        promise_setup(() => Promise.resolve(), {});
+        promise_test(() => Promise.resolve(), 'after');
+        throw new Error('this error is expected');
+      }
+    ).then(({harness, tests}) => {
+      assert_equals(harness, 'ERROR');
+      assert_equals(tests.before, 'PASS');
+      assert_equals(tests.after, 'PASS');
+    });
+}, 'Does not apply unspecified configuration properties');
+
+promise_test(() => {
+  return makeTest(
+      () => {
+        var properties = {
+          allow_uncaught_exception: true
+        };
+        test(() => {}, 'before');
+        promise_setup(() => Promise.resolve(), properties);
+        promise_test(() => Promise.resolve(), 'after');
+        throw new Error('this error is expected');
+      }
+    ).then(({harness, tests}) => {
+      assert_equals(harness, 'ERROR');
+      assert_equals(tests.before, 'PASS');
+      assert_equals(tests.after, 'PASS');
+    });
+}, 'Ignores configuration properties when some tests have already run');
+
+promise_test(() => {
+  return makeTest(
+      () => {
+        var properties = {
+          allow_uncaught_exception: true
+        };
+        promise_setup(() => Promise.resolve(), properties);
+        promise_test(() => {
+          return new Promise((resolve) => {
+            setTimeout(() => {
+              resolve();
+              throw new Error('this error is expected');
+            });
+          });
+        }, 'after');
+      }
+    ).then(({harness, tests}) => {
+      assert_equals(harness, 'OK');
+      assert_equals(tests.after, 'PASS');
+    });
+}, 'Honors configuration properties');
+
+promise_test(() => {
+  return makeTest(
+      () => {
+        // Ensure that the harness error is the result of explicit error
+        // handling
+        setup({ allow_uncaught_exception: true });
+
+        test(() => {}, 'before');
+        promise_setup(() => { throw new Error('this error is expected'); });
+        promise_test(() => Promise.resolve(), 'after');
+      }
+    ).then(({harness, tests}) => {
+      assert_equals(harness, 'ERROR');
+      assert_equals(tests.before, 'PASS');
+      assert_equals(tests.after, 'NOTRUN');
+    });
+}, 'Error for synchronous exceptions');
+
+promise_test(() => {
+  return makeTest(
+      () => {
+        // Ensure that the harness error is the result of explicit error
+        // handling
+        setup({ allow_uncaught_exception: true });
+
+        test(() => {}, 'before');
+        promise_setup(() => undefined);
+        promise_test(() => Promise.resolve(), 'after');
+      }
+    ).then(({harness, tests}) => {
+      assert_equals(harness, 'ERROR');
+      assert_equals(tests.before, 'PASS');
+      assert_equals(tests.after, 'NOTRUN');
+    });
+}, 'Error for missing return value');
+
+promise_test(() => {
+  return makeTest(
+      () => {
+        // Ensure that the harness error is the result of explicit error
+        // handling
+        setup({ allow_uncaught_exception: true });
+
+        test(() => {}, 'before');
+        var noThen = Promise.resolve();
+        noThen.then = undefined;
+        promise_setup(() => noThen);
+        promise_test(() => Promise.resolve(), 'after');
+      }
+    ).then(({harness, tests}) => {
+      assert_equals(harness, 'ERROR');
+      assert_equals(tests.before, 'PASS');
+      assert_equals(tests.after, 'NOTRUN');
+    });
+}, 'Error for non-thenable return value');
+
+promise_test(() => {
+  return makeTest(
+      () => {
+        // Ensure that the harness error is the result of explicit error
+        // handling
+        setup({ allow_uncaught_exception: true });
+
+        test(() => {}, 'before');
+        var poisonedThen = {
+          get then() {
+            throw new Error('this error is expected');
+          }
+        };
+        promise_setup(() => poisonedThen);
+        promise_test(() => Promise.resolve(), 'after');
+      }
+    ).then(({harness, tests}) => {
+      assert_equals(harness, 'ERROR');
+      assert_equals(tests.before, 'PASS');
+      assert_equals(tests.after, 'NOTRUN');
+    });
+}, 'Error for "poisoned" `then` property');
+
+promise_test(() => {
+  return makeTest(
+      () => {
+        // Ensure that the harness error is the result of explicit error
+        // handling
+        setup({ allow_uncaught_exception: true });
+
+        test(() => {}, 'before');
+        var badThen = {
+          then() {
+            throw new Error('this error is expected');
+          }
+        };
+        promise_setup(() => badThen);
+        promise_test(() => Promise.resolve(), 'after');
+      }
+    ).then(({harness, tests}) => {
+      assert_equals(harness, 'ERROR');
+      assert_equals(tests.before, 'PASS');
+      assert_equals(tests.after, 'NOTRUN');
+    });
+}, 'Error for synchronous error from `then` method');
+
+promise_test(() => {
+  return makeTest(
+      () => {
+        // Ensure that the harness error is the result of explicit error
+        // handling
+        setup({ allow_uncaught_exception: true });
+
+        test(() => {}, 'before');
+        promise_setup(() => Promise.resolve());
+        test(() => {}, 'after');
+      }
+    ).then(({harness, tests}) => {
+      assert_equals(harness, 'ERROR');
+      assert_equals(tests.before, 'PASS');
+      assert_equals(tests.after, undefined);
+    });
+}, 'Error for subsequent invocation of `test`');
+
+promise_test(() => {
+  return makeTest(
+      () => {
+        // Ensure that the harness error is the result of explicit error
+        // handling
+        setup({ allow_uncaught_exception: true });
+
+        test(() => {}, 'before');
+        promise_setup(() => Promise.resolve());
+        async_test((t) => t.done(), 'after');
+      }
+    ).then(({harness, tests}) => {
+      assert_equals(harness, 'ERROR');
+      assert_equals(tests.before, 'PASS');
+      assert_equals(tests.after, undefined);
+    });
+}, 'Error for subsequent invocation of `async_test`');
+
+promise_test(() => {
+  return makeTest(
+      () => {
+        // Ensure that the harness error is the result of explicit error
+        // handling
+        setup({ allow_uncaught_exception: true });
+
+        test(() => {}, 'before');
+        promise_setup(() => Promise.reject());
+        promise_test(() => Promise.resolve(), 'after');
+      }
+    ).then(({harness, tests}) => {
+      assert_equals(harness, 'ERROR');
+      assert_equals(tests.before, 'PASS');
+      assert_equals(tests.after, 'NOTRUN');
+    });
+}, 'Error for rejected promise');
+
+promise_test(() => {
+  var expected_sequence = [
+    'test body',
+    'promise_setup begin',
+    'promise_setup end',
+    'promise_test body'
+  ];
+  var actual_sequence = window.actual_sequence = [];
+
+  return makeTest(
+      () => {
+        test(() => { parent.actual_sequence.push('test body'); }, 'before');
+        promise_setup(() => {
+          parent.actual_sequence.push('promise_setup begin');
+
+          return Promise.resolve()
+            .then(() => new Promise((resolve) => setTimeout(resolve, 300)))
+            .then(() => parent.actual_sequence.push('promise_setup end'));
+        });
+        promise_test(() => {
+          parent.actual_sequence.push('promise_test body');
+          return Promise.resolve();
+        }, 'after');
+      }
+    ).then(({harness, tests}) => {
+      assert_equals(harness, 'OK');
+      assert_equals(tests.before, 'PASS');
+      assert_equals(tests.after, 'PASS');
+      assert_array_equals(actual_sequence, expected_sequence);
+    });
+}, 'Waits for promise to settle');
+
+promise_test(() => {
+  var expected_sequence = [
+    'promise_test 1 begin',
+    'promise_test 1 end',
+    'promise_setup begin',
+    'promise_setup end',
+    'promise_test 2 body'
+  ];
+  var actual_sequence = window.actual_sequence = [];
+
+  return makeTest(
+      () => {
+        promise_test((t) => {
+          parent.actual_sequence.push('promise_test 1 begin');
+
+          return Promise.resolve()
+            .then(() => new Promise((resolve) => t.step_timeout(resolve, 300)))
+            .then(() => parent.actual_sequence.push('promise_test 1 end'));
+        }, 'before');
+        promise_setup(() => {
+          parent.actual_sequence.push('promise_setup begin');
+
+          return Promise.resolve()
+            .then(() => new Promise((resolve) => setTimeout(resolve, 300)))
+            .then(() => parent.actual_sequence.push('promise_setup end'));
+        });
+        promise_test(() => {
+          parent.actual_sequence.push('promise_test 2 body');
+          return Promise.resolve();
+        }, 'after');
+      }
+    ).then(({harness, tests}) => {
+      assert_equals(harness, 'OK');
+      assert_equals(tests.before, 'PASS');
+      assert_equals(tests.after, 'PASS');
+      assert_array_equals(actual_sequence, expected_sequence);
+    });
+}, 'Waits for existing promise_test to complete');
+
+promise_test(() => {
+  return makeTest(
+      () => {
+        var properties = { allow_uncaught_exception: true };
+        promise_test(() => {
+          return new Promise((resolve) => {
+            setTimeout(() => {
+              resolve();
+              throw new Error('this error is expected');
+            });
+          });
+        }, 'before');
+        promise_setup(() => Promise.resolve(), properties);
+      }
+    ).then(({harness, tests}) => {
+      assert_equals(harness, 'ERROR');
+      assert_equals(tests.before, 'PASS');
+    });
+}, 'Defers application of setup properties');
+</script>
+</body>
+</html>
diff --git a/test/wpt/tests/resources/test/tests/unit/single_test.html b/test/wpt/tests/resources/test/tests/unit/single_test.html
new file mode 100644
index 0000000..ff766e6
--- /dev/null
+++ b/test/wpt/tests/resources/test/tests/unit/single_test.html
@@ -0,0 +1,94 @@
+<!DOCTYPE HTML>
+<html>
+<head>
+  <meta charset="utf-8">
+  <meta name="timeout" content="long">
+  <script src="/resources/testharness.js"></script>
+  <script src="../../nested-testharness.js"></script>
+  <title>single_test</title>
+</head>
+<body>
+<script>
+promise_test(() => {
+  return makeTest(
+      () => {
+        setup({ single_test: true });
+        done();
+      }
+    ).then(({harness, tests}) => {
+      assert_equals(harness, 'OK');
+      assert_equals(tests['Document title'], 'PASS');
+    });
+}, 'Expected usage');
+
+promise_test(() => {
+  return makeTest(
+      () => {
+        setup({ single_test: true });
+        throw new Error('this error is expected');
+      }
+    ).then(({harness, tests}) => {
+      assert_equals(harness, 'OK');
+      assert_equals(tests['Document title'], 'FAIL');
+    });
+}, 'Uncaught exception');
+
+promise_test(() => {
+  return makeTest(
+      () => {
+        setup({ single_test: true });
+        Promise.reject(new Error('this error is expected'));
+      }
+    ).then(({harness, tests}) => {
+      assert_equals(harness, 'OK');
+      assert_equals(tests['Document title'], 'FAIL');
+    });
+}, 'Unhandled rejection');
+
+promise_test(() => {
+  return makeTest(
+      () => {
+        setup({ single_test: true });
+        test(function() {}, 'sync test');
+      }
+    ).then(({harness, tests}) => {
+      assert_equals(harness, 'OK');
+      assert_equals(tests['Document title'], 'FAIL');
+      assert_equals(
+        Object.keys(tests).length, 1, 'no additional subtests created'
+      );
+    });
+}, 'Erroneous usage: subtest declaration (synchronous test)');
+
+promise_test(() => {
+  return makeTest(
+      () => {
+        setup({ single_test: true });
+        async_test(function(t) { t.done(); }, 'async test');
+      }
+    ).then(({harness, tests}) => {
+      assert_equals(harness, 'OK');
+      assert_equals(tests['Document title'], 'FAIL');
+      assert_equals(
+        Object.keys(tests).length, 1, 'no additional subtests created'
+      );
+    });
+}, 'Erroneous usage: subtest declaration (asynchronous test)');
+
+promise_test(() => {
+  return makeTest(
+      () => {
+        setup({ single_test: true });
+        promise_test(function() { return Promise.resolve(); }, 'promise test');
+      }
+    ).then(({harness, tests}) => {
+      assert_equals(harness, 'OK');
+      assert_equals(tests['Document title'], 'FAIL');
+      assert_equals(
+        Object.keys(tests).length, 1, 'no additional subtests created'
+      );
+    });
+}, 'Erroneous usage: subtest declaration (promise test)');
+</script>
+</body>
+</html>
diff --git a/test/wpt/tests/resources/test/tests/unit/test-return-restrictions.html b/test/wpt/tests/resources/test/tests/unit/test-return-restrictions.html
new file mode 100644
index 0000000..0295c52
--- /dev/null
+++ b/test/wpt/tests/resources/test/tests/unit/test-return-restrictions.html
@@ -0,0 +1,156 @@
+<!DOCTYPE HTML>
+<html>
+<head>
+  <meta charset="utf-8">
+  <script src="/resources/testharness.js"></script>
+  <title>Restrictions on return value from `test`</title>
+</head>
+<body>
+<script>
+function makeTest(...bodies) {
+  const closeScript = '<' + '/script>';
+  let src = `
+<!DOCTYPE HTML>
+<html>
+<head>
+<title>Document title</title>
+<script src="/resources/testharness.js?${Math.random()}">${closeScript}
+</head>
+
+<body>
+<div id="log"></div>`;
+  bodies.forEach((body) => {
+    src += '<script>(' + body + ')();' + closeScript;
+  });
+
+  const iframe = document.createElement('iframe');
+
+  document.body.appendChild(iframe);
+  iframe.contentDocument.write(src);
+
+  return new Promise((resolve) => {
+    window.addEventListener('message', function onMessage(e) {
+      if (e.source !== iframe.contentWindow) {
+        return;
+      }
+      if (!e.data || e.data.type !=='complete') {
+        return;
+      }
+      window.removeEventListener('message', onMessage);
+      resolve(e.data);
+    });
+
+    iframe.contentDocument.close();
+  }).then(({ tests, status }) => {
+    const summary = {
+      harness: {
+        status: getEnumProp(status, status.status),
+        message: status.message
+      },
+      tests: {}
+    };
+
+    tests.forEach((test) => {
+      summary.tests[test.name] = getEnumProp(test, test.status);
+    });
+
+    return summary;
+  });
+}
+
+function getEnumProp(object, value) {
+  for (let property in object) {
+    if (!/^[A-Z]+$/.test(property)) {
+      continue;
+    }
+
+    if (object[property] === value) {
+      return property;
+    }
+  }
+}
+
+promise_test(() => {
+  return makeTest(
+      () => {
+        test(() => undefined, 'before');
+        test(() => null, 'null');
+        test(() => undefined, 'after');
+      }
+    ).then(({harness, tests}) => {
+      assert_equals(harness.status, 'ERROR');
+      assert_equals(
+        harness.message,
+        'Test named "null" passed a function to `test` that returned a value.'
+      );
+      assert_equals(tests.before, 'PASS');
+      assert_equals(tests.null, 'PASS');
+      assert_equals(tests.after, 'PASS');
+    });
+}, 'test returning `null`');
+
+promise_test(() => {
+  return makeTest(
+      () => {
+        test(() => undefined, 'before');
+        test(() => ({}), 'object');
+        test(() => undefined, 'after');
+      }
+    ).then(({harness, tests}) => {
+      assert_equals(harness.status, 'ERROR');
+      assert_equals(
+        harness.message,
+        'Test named "object" passed a function to `test` that returned a value.'
+      );
+      assert_equals(tests.before, 'PASS');
+      assert_equals(tests.object, 'PASS');
+      assert_equals(tests.after, 'PASS');
+    });
+}, 'test returning an ordinary object');
+
+promise_test(() => {
+  return makeTest(
+      () => {
+        test(() => undefined, 'before');
+        test(() => Promise.resolve(5), 'thenable');
+        test(() => undefined, 'after');
+      }
+    ).then(({harness, tests}) => {
+      assert_equals(harness.status, 'ERROR');
+      assert_equals(
+        harness.message,
+        'Test named "thenable" passed a function to `test` that returned a value. ' +
+        'Consider using `promise_test` instead when using Promises or async/await.'
+      );
+      assert_equals(tests.before, 'PASS');
+      assert_equals(tests.thenable, 'PASS');
+      assert_equals(tests.after, 'PASS');
+    });
+}, 'test returning a thenable object');
+
+promise_test(() => {
+  return makeTest(
+      () => {
+        test(() => undefined, 'before');
+        test(() => {
+          const iframe = document.createElement('iframe');
+          iframe.setAttribute('sandbox', '');
+          document.body.appendChild(iframe);
+          return iframe.contentWindow;
+        }, 'restricted');
+        test(() => undefined, 'after');
+      }
+    ).then(({harness, tests}) => {
+      assert_equals(harness.status, 'ERROR');
+      assert_equals(
+        harness.message,
+        'Test named "restricted" passed a function to `test` that returned a value.'
+      );
+      assert_equals(tests.before, 'PASS');
+      assert_equals(tests.restricted, 'PASS');
+      assert_equals(tests.after, 'PASS');
+    });
+}, 'test returning a restricted object');
+</script>
+</body>
+</html>
diff --git a/test/wpt/tests/resources/test/tests/unit/throwing-assertions.html b/test/wpt/tests/resources/test/tests/unit/throwing-assertions.html
new file mode 100644
index 0000000..a36a560
--- /dev/null
+++ b/test/wpt/tests/resources/test/tests/unit/throwing-assertions.html
@@ -0,0 +1,268 @@
+<!DOCTYPE HTML>
+<html>
+<head>
+  <meta charset="utf-8">
+  <meta name="timeout" content="long">
+  <script src="/resources/testharness.js"></script>
+  <title>Test the methods that make assertions about exceptions</title>
+</head>
+<body>
+<script>
+function makeTest(...bodies) {
+  const closeScript = '<' + '/script>';
+  let src = `
+<!DOCTYPE HTML>
+<html>
+<head>
+<title>Document title</title>
+<script src="/resources/testharness.js?${Math.random()}">${closeScript}
+</head>
+
+<body>
+<div id="log"></div>`;
+  bodies.forEach((body) => {
+    src += '<script>(' + body + ')();' + closeScript;
+  });
+
+  const iframe = document.createElement('iframe');
+
+  document.body.appendChild(iframe);
+  iframe.contentDocument.write(src);
+
+  return new Promise((resolve) => {
+    window.addEventListener('message', function onMessage(e) {
+      if (e.source !== iframe.contentWindow) {
+        return;
+      }
+      if (!e.data || e.data.type !=='complete') {
+        return;
+      }
+      window.removeEventListener('message', onMessage);
+      resolve(e.data);
+    });
+
+    iframe.contentDocument.close();
+  }).then(({ tests, status }) => {
+    const summary = {
+      harness: getEnumProp(status, status.status),
+      tests: {}
+    };
+
+    tests.forEach((test) => {
+      summary.tests[test.name] = getEnumProp(test, test.status);
+    });
+
+    return summary;
+  });
+}
+
+function getEnumProp(object, value) {
+  for (let property in object) {
+    if (!/^[A-Z]+$/.test(property)) {
+      continue;
+    }
+
+    if (object[property] === value) {
+      return property;
+    }
+  }
+}
+
+promise_test(() => {
+  return makeTest(() => {
+    test(() => {
+      assert_throws_js(TypeError, () => { throw new TypeError(); });
+    });
+  }).then(({harness, tests}) => {
+    assert_equals(harness, 'OK');
+    assert_equals(tests['Document title'], 'PASS');
+  });
+}, 'assert_throws_js on a TypeError');
+
+promise_test(() => {
+  return makeTest(() => {
+    test(() => {
+      assert_throws_js(RangeError, () => { throw new RangeError(); });
+    });
+  }).then(({harness, tests}) => {
+    assert_equals(harness, 'OK');
+    assert_equals(tests['Document title'], 'PASS');
+  });
+}, 'assert_throws_js on a RangeError');
+
+promise_test(() => {
+  return makeTest(() => {
+    test(() => {
+      assert_throws_js(TypeError, () => { throw new RangeError(); });
+    });
+  }).then(({harness, tests}) => {
+    assert_equals(harness, 'OK');
+    assert_equals(tests['Document title'], 'FAIL');
+  });
+}, 'assert_throws_js on a TypeError when RangeError is thrown');
+
+promise_test(() => {
+  return makeTest(() => {
+    test(() => {
+      assert_throws_js(Error, () => { throw new TypeError(); });
+    });
+  }).then(({harness, tests}) => {
+    assert_equals(harness, 'OK');
+    assert_equals(tests['Document title'], 'FAIL');
+  });
+}, 'assert_throws_js on an Error when TypeError is thrown');
+
+promise_test(() => {
+  return makeTest(() => {
+    test(() => {
+      assert_throws_js(Error,
+                       () => { throw new DOMException("hello", "Error"); });
+    });
+  }).then(({harness, tests}) => {
+    assert_equals(harness, 'OK');
+    assert_equals(tests['Document title'], 'FAIL');
+  });
+}, 'assert_throws_js on an Error when a DOMException is thrown');
+
+promise_test(() => {
+  return makeTest(() => {
+    test(() => {
+      assert_throws_js(SyntaxError,
+                       () => { throw new DOMException("hey", "SyntaxError"); });
+    });
+  }).then(({harness, tests}) => {
+    assert_equals(harness, 'OK');
+    assert_equals(tests['Document title'], 'FAIL');
+  });
+}, 'assert_throws_js on a SyntaxError when a DOMException is thrown');
+
+promise_test(() => {
+  return makeTest(() => {
+    test(() => {
+      assert_throws_dom("SyntaxError",
+                        () => { throw new DOMException("x", "SyntaxError"); });
+    });
+  }).then(({harness, tests}) => {
+    assert_equals(harness, 'OK');
+    assert_equals(tests['Document title'], 'PASS');
+  });
+}, 'assert_throws_dom basic sanity');
+
+promise_test(() => {
+  return makeTest(() => {
+    test(() => {
+      assert_throws_dom(12,
+                        () => { throw new DOMException("x", "SyntaxError"); });
+    });
+  }).then(({harness, tests}) => {
+    assert_equals(harness, 'OK');
+    assert_equals(tests['Document title'], 'PASS');
+  });
+}, 'assert_throws_dom with numeric code');
+
+promise_test(() => {
+  return makeTest(() => {
+    test(() => {
+      assert_throws_dom("SYNTAX_ERR",
+                        () => { throw new DOMException("x", "SyntaxError"); });
+    });
+  }).then(({harness, tests}) => {
+    assert_equals(harness, 'OK');
+    assert_equals(tests['Document title'], 'PASS');
+  });
+}, 'assert_throws_dom with string name for code');
+
+promise_test(() => {
+  return makeTest(() => {
+    test(() => {
+      assert_throws_dom("DataError",
+                        () => { throw new DOMException("x", "DataError"); });
+    });
+  }).then(({harness, tests}) => {
+    assert_equals(harness, 'OK');
+    assert_equals(tests['Document title'], 'PASS');
+  });
+}, 'assert_throws_dom for a code-less DOMException type');
+
+promise_test(() => {
+  return makeTest(() => {
+    test(() => {
+      assert_throws_dom("NoSuchError",
+                        () => { throw new DOMException("x", "NoSuchError"); });
+    });
+  }).then(({harness, tests}) => {
+    assert_equals(harness, 'OK');
+    assert_equals(tests['Document title'], 'FAIL');
+  });
+}, 'assert_throws_dom for a nonexistent DOMException type');
+
+promise_test(() => {
+  return makeTest(() => {
+    test(() => {
+      assert_throws_dom("SyntaxError", () => { throw new SyntaxError(); });
+    });
+  }).then(({harness, tests}) => {
+    assert_equals(harness, 'OK');
+    assert_equals(tests['Document title'], 'FAIL');
+  });
+}, 'assert_throws_dom when a non-DOM exception is thrown');
+
+promise_test(() => {
+  return makeTest(() => {
+    test(() => {
+      assert_throws_exactly(5, () => { throw 5; });
+    });
+  }).then(({harness, tests}) => {
+    assert_equals(harness, 'OK');
+    assert_equals(tests['Document title'], 'PASS');
+  });
+}, 'assert_throws_exactly with number');
+
+promise_test(() => {
+  return makeTest(() => {
+    test(() => {
+      assert_throws_exactly("foo", () => { throw "foo"; });
+    });
+  }).then(({harness, tests}) => {
+    assert_equals(harness, 'OK');
+    assert_equals(tests['Document title'], 'PASS');
+  });
+}, 'assert_throws_exactly with string');
+
+promise_test(() => {
+  return makeTest(() => {
+    test(() => {
+      assert_throws_exactly({}, () => { throw {}; });
+    });
+  }).then(({harness, tests}) => {
+    assert_equals(harness, 'OK');
+    assert_equals(tests['Document title'], 'FAIL');
+  });
+}, 'assert_throws_exactly with different objects');
+
+promise_test(() => {
+  return makeTest(() => {
+    test(() => {
+      var obj = {};
+      assert_throws_exactly(obj, () => { throw obj; });
+    });
+  }).then(({harness, tests}) => {
+    assert_equals(harness, 'OK');
+    assert_equals(tests['Document title'], 'PASS');
+  });
+}, 'assert_throws_exactly with same object');
+
+promise_test(() => {
+  return makeTest(() => {
+    test(() => {
+      assert_throws_exactly(TypeError, () => { throw new TypeError; });
+    });
+  }).then(({harness, tests}) => {
+    assert_equals(harness, 'OK');
+    assert_equals(tests['Document title'], 'FAIL');
+  });
+}, 'assert_throws_exactly with bogus TypeError bits ');
+
+</script>
+</body>
+</html>
diff --git a/test/wpt/tests/resources/test/tests/unit/unpaired-surrogates.html b/test/wpt/tests/resources/test/tests/unit/unpaired-surrogates.html
new file mode 100644
index 0000000..b232111
--- /dev/null
+++ b/test/wpt/tests/resources/test/tests/unit/unpaired-surrogates.html
@@ -0,0 +1,143 @@
+<!DOCTYPE HTML>
+<html>
+<head>
+  <meta charset="utf-8">
+  <script src="/resources/testharness.js"></script>
+  <title>Restrictions on return value from `test`</title>
+</head>
+<body>
+<script>
+function makeTest(...bodies) {
+  const closeScript = '<' + '/script>';
+  let src = `
+<!DOCTYPE HTML>
+<html>
+<head>
+<title>Document title</title>
+<script src="/resources/testharness.js?${Math.random()}">${closeScript}
+</head>
+
+<body>
+<div id="log"></div>`;
+  bodies.forEach((body) => {
+    src += '<script>(' + body + ')();' + closeScript;
+  });
+
+  const iframe = document.createElement('iframe');
+
+  document.body.appendChild(iframe);
+  iframe.contentDocument.write(src);
+
+  return new Promise((resolve) => {
+    window.addEventListener('message', function onMessage(e) {
+      if (e.source !== iframe.contentWindow) {
+        return;
+      }
+      if (!e.data || e.data.type !=='complete') {
+        return;
+      }
+      window.removeEventListener('message', onMessage);
+      resolve(e.data);
+    });
+
+    iframe.contentDocument.close();
+  }).then(({ tests, status }) => {
+    const summary = {
+      harness: {
+        status: getEnumProp(status, status.status),
+        message: status.message
+      },
+      tests: {}
+    };
+
+    tests.forEach((test) => {
+      summary.tests[test.name] = getEnumProp(test, test.status);
+    });
+
+    return summary;
+  });
+}
+
+function getEnumProp(object, value) {
+  for (let property in object) {
+    if (!/^[A-Z]+$/.test(property)) {
+      continue;
+    }
+
+    if (object[property] === value) {
+      return property;
+    }
+  }
+}
+
+promise_test(() => {
+  return makeTest(
+      () => {
+        test(() => {}, 'before');
+        test(() => {}, 'U+d7ff is not modified: \ud7ff');
+        test(() => {}, 'U+e000 is not modified: \ue000');
+        test(() => {}, 'after');
+      }
+    ).then(({harness, tests}) => {
+      assert_equals(harness.status, 'OK');
+      assert_equals(harness.message, null);
+      assert_equals(tests.before, 'PASS');
+      assert_equals(tests['U+d7ff is not modified: \ud7ff'], 'PASS');
+      assert_equals(tests['U+e000 is not modified: \ue000'], 'PASS');
+      assert_equals(tests.after, 'PASS');
+    });
+}, 'sub-test names which include valid code units');
+
+promise_test(() => {
+  return makeTest(
+      () => {
+        test(() => {}, 'before');
+        test(() => {}, 'U+d800U+dfff is not modified: \ud800\udfff');
+        test(() => {}, 'U+dbffU+dc00 is not modified: \udbff\udc00');
+        test(() => {}, 'after');
+      }
+    ).then(({harness, tests}) => {
+      assert_equals(harness.status, 'OK');
+      assert_equals(harness.message, null);
+      assert_equals(tests.before, 'PASS');
+      assert_equals(tests['U+d800U+dfff is not modified: \ud800\udfff'], 'PASS');
+      assert_equals(tests['U+dbffU+dc00 is not modified: \udbff\udc00'], 'PASS');
+      assert_equals(tests.after, 'PASS');
+    });
+}, 'sub-test names which include paired surrogates');
+
+promise_test(() => {
+  return makeTest(
+      () => {
+        test(() => {}, 'before');
+        test(() => {}, 'U+d800 must be sanitized: \ud800');
+        test(() => {}, 'U+d800U+d801 must be sanitized: \ud800\ud801');
+        test(() => {}, 'U+dfff must be sanitized: \udfff');
+        test(() => {}, 'U+dc00U+d800U+dc00U+d800 must be sanitized: \udc00\ud800\udc00\ud800');
+        test(() => {}, 'U+dbffU+dfffU+dfff must be sanitized: \udbff\udfff\udfff');
+        test(() => {}, 'after');
+      }
+    ).then(({harness, tests}) => {
+      assert_equals(harness.status, 'OK');
+      assert_equals(harness.message, null);
+      assert_equals(tests.before, 'PASS');
+      assert_equals(tests['U+d800 must be sanitized: U+d800'], 'PASS');
+      assert_equals(tests['U+dfff must be sanitized: U+dfff'], 'PASS');
+      assert_equals(
+        tests['U+d800U+d801 must be sanitized: U+d800U+d801'],
+        'PASS'
+      );
+      assert_equals(
+        tests['U+dc00U+d800U+dc00U+d800 must be sanitized: U+dc00\ud800\udc00U+d800'],
+        'PASS'
+      );
+      assert_equals(
+        tests['U+dbffU+dfffU+dfff must be sanitized: \udbff\udfffU+dfff'],
+        'PASS'
+      );
+      assert_equals(tests.after, 'PASS');
+    });
+}, 'sub-test names which include unpaired surrogates');
+</script>
+</body>
+</html>
diff --git a/test/wpt/tests/resources/test/tox.ini b/test/wpt/tests/resources/test/tox.ini
new file mode 100644
index 0000000..12013a1
--- /dev/null
+++ b/test/wpt/tests/resources/test/tox.ini
@@ -0,0 +1,13 @@
+[tox]
+envlist = py37,py38,py39,py310,py311
+skipsdist=True
+
+[testenv]
+passenv=DISPLAY # Necessary for the spawned GeckoDriver process to connect to
+                # the appropriate display.
+
+deps =
+  -r{toxinidir}/../../tools/requirements_pytest.txt
+  -r{toxinidir}/requirements.txt
+
+commands = pytest -vv {posargs}
diff --git a/test/wpt/tests/resources/test/wptserver.py b/test/wpt/tests/resources/test/wptserver.py
new file mode 100644
index 0000000..1f913dd
--- /dev/null
+++ b/test/wpt/tests/resources/test/wptserver.py
@@ -0,0 +1,58 @@
+import logging
+import os
+import subprocess
+import time
+import sys
+import urllib
+
+
+class WPTServer(object):
+    def __init__(self, wpt_root):
+        self.logger = logging.getLogger()
+        self.wpt_root = wpt_root
+
+        # This is a terrible hack to get the default config of wptserve.
+        sys.path.insert(0, os.path.join(wpt_root, "tools"))
+        from serve.serve import build_config
+        with build_config(self.logger) as config:
+            self.host = config["browser_host"]
+            self.http_port = config["ports"]["http"][0]
+            self.https_port = config["ports"]["https"][0]
+
+        self.base_url = 'http://%s:%s' % (self.host, self.http_port)
+        self.https_base_url = 'https://%s:%s' % (self.host, self.https_port)
+
+    def start(self, ssl_context):
+        self.devnull = open(os.devnull, 'w')
+        wptserve_cmd = [os.path.join(self.wpt_root, 'wpt'), 'serve']
+        if sys.executable:
+            wptserve_cmd[0:0] = [sys.executable]
+        self.logger.info('Executing %s' % ' '.join(wptserve_cmd))
+        self.proc = subprocess.Popen(
+            wptserve_cmd,
+            stderr=self.devnull,
+            cwd=self.wpt_root)
+
+        for retry in range(5):
+            # Exponential backoff.
+            time.sleep(2 ** retry)
+            exit_code = self.proc.poll()
+            if exit_code != None:
+                logging.warning('Command "%s" exited with %s', ' '.join(wptserve_cmd), exit_code)
+                break
+            try:
+                urllib.request.urlopen(self.base_url, timeout=1)
+                urllib.request.urlopen(self.https_base_url, timeout=1, context=ssl_context)
+                return
+            except urllib.error.URLError:
+                pass
+
+        raise Exception('Could not start wptserve on %s' % self.base_url)
+
+    def stop(self):
+        self.proc.terminate()
+        self.proc.wait()
+        self.devnull.close()
+
+    def url(self, abs_path):
+        return self.https_base_url + '/' + os.path.relpath(abs_path, self.wpt_root)
diff --git a/test/wpt/tests/resources/testdriver-actions.js b/test/wpt/tests/resources/testdriver-actions.js
new file mode 100644
index 0000000..3e5ba74
--- /dev/null
+++ b/test/wpt/tests/resources/testdriver-actions.js
@@ -0,0 +1,599 @@
+(function() {
+  let sourceNameIdx = 0;
+
+  /**
+   * @class
+   * Builder for creating a sequence of actions
+   *
+   *
+   * The actions are dispatched once
+   * :js:func:`test_driver.Actions.send` is called. This returns a
+   * promise which resolves once the actions are complete.
+   *
+   * The other methods on :js:class:`test_driver.Actions` object are
+   * used to build the sequence of actions that will be sent. These
+   * return the `Actions` object itself, so the actions sequence can
+   * be constructed by chaining method calls.
+   *
+   * Internally :js:func:`test_driver.Actions.send` invokes
+   * :js:func:`test_driver.action_sequence`.
+   *
+   * @example
+   * let text_box = document.getElementById("text");
+   *
+   * let actions = new test_driver.Actions()
+   *    .pointerMove(0, 0, {origin: text_box})
+   *    .pointerDown()
+   *    .pointerUp()
+   *    .addTick()
+   *    .keyDown("p")
+   *    .keyUp("p");
+   *
+   * await actions.send();
+   *
+   * @param {number} [defaultTickDuration] - The default duration of a
+   * tick. Be default this is set ot 16ms, which is one frame time
+   * based on 60Hz display.
+   */
+  function Actions(defaultTickDuration=16) {
+    this.sourceTypes = new Map([["key", KeySource],
+                                ["pointer", PointerSource],
+                                ["wheel", WheelSource],
+                                ["none", GeneralSource]]);
+    this.sources = new Map();
+    this.sourceOrder = [];
+    for (let sourceType of this.sourceTypes.keys()) {
+      this.sources.set(sourceType, new Map());
+    }
+    this.currentSources = new Map();
+    for (let sourceType of this.sourceTypes.keys()) {
+      this.currentSources.set(sourceType, null);
+    }
+    this.createSource("none");
+    this.tickIdx = 0;
+    this.defaultTickDuration = defaultTickDuration;
+    this.context = null;
+  }
+
+  Actions.prototype = {
+    ButtonType: {
+      LEFT: 0,
+      MIDDLE: 1,
+      RIGHT: 2,
+      BACK: 3,
+      FORWARD: 4,
+    },
+
+    /**
+     * Generate the action sequence suitable for passing to
+     * test_driver.action_sequence
+     *
+     * @returns {Array} Array of WebDriver-compatible actions sequences
+     */
+    serialize: function() {
+      let actions = [];
+      for (let [sourceType, sourceName] of this.sourceOrder) {
+        let source = this.sources.get(sourceType).get(sourceName);
+        let serialized = source.serialize(this.tickIdx + 1, this.defaultTickDuration);
+        if (serialized) {
+          serialized.id = sourceName;
+          actions.push(serialized);
+        }
+      }
+      return actions;
+    },
+
+    /**
+     * Generate and send the action sequence
+     *
+     * @returns {Promise} fulfilled after the sequence is executed,
+     *                    rejected if any actions fail.
+     */
+    send: function() {
+      let actions;
+      try {
+        actions = this.serialize();
+      } catch(e) {
+        return Promise.reject(e);
+      }
+      return test_driver.action_sequence(actions, this.context);
+    },
+
+    /**
+     * Set the context for the actions
+     *
+     * @param {WindowProxy} context - Context in which to run the action sequence
+     */
+    setContext: function(context) {
+      this.context = context;
+      return this;
+    },
+
+    /**
+     * Get the action source with a particular source type and name.
+     * If no name is passed, a new source with the given type is
+     * created.
+     *
+     * @param {String} type - Source type ('none', 'key', 'pointer', or 'wheel')
+     * @param {String?} name - Name of the source
+     * @returns {Source} Source object for that source.
+     */
+    getSource: function(type, name) {
+      if (!this.sources.has(type)) {
+        throw new Error(`${type} is not a valid action type`);
+      }
+      if (name === null || name === undefined) {
+        name = this.currentSources.get(type);
+      }
+      if (name === null || name === undefined) {
+        return this.createSource(type, null);
+      }
+      return this.sources.get(type).get(name);
+    },
+
+    setSource: function(type, name) {
+      if (!this.sources.has(type)) {
+        throw new Error(`${type} is not a valid action type`);
+      }
+      if (!this.sources.get(type).has(name)) {
+        throw new Error(`${name} is not a valid source for ${type}`);
+      }
+      this.currentSources.set(type, name);
+      return this;
+    },
+
+    /**
+     * Add a new key input source with the given name
+     *
+     * @param {String} name - Name of the key source
+     * @param {Bool} set - Set source as the default key source
+     * @returns {Actions}
+     */
+    addKeyboard: function(name, set=true) {
+      this.createSource("key", name);
+      if (set) {
+        this.setKeyboard(name);
+      }
+      return this;
+    },
+
+    /**
+     * Set the current default key source
+     *
+     * @param {String} name - Name of the key source
+     * @returns {Actions}
+     */
+    setKeyboard: function(name) {
+      this.setSource("key", name);
+      return this;
+    },
+
+    /**
+     * Add a new pointer input source with the given name
+     *
+     * @param {String} type - Name of the pointer source
+     * @param {String} pointerType - Type of pointing device
+     * @param {Bool} set - Set source as the default pointer source
+     * @returns {Actions}
+     */
+    addPointer: function(name, pointerType="mouse", set=true) {
+      this.createSource("pointer", name, {pointerType: pointerType});
+      if (set) {
+        this.setPointer(name);
+      }
+      return this;
+    },
+
+    /**
+     * Set the current default pointer source
+     *
+     * @param {String} name - Name of the pointer source
+     * @returns {Actions}
+     */
+    setPointer: function(name) {
+      this.setSource("pointer", name);
+      return this;
+    },
+
+    /**
+     * Add a new wheel input source with the given name
+     *
+     * @param {String} type - Name of the wheel source
+     * @param {Bool} set - Set source as the default wheel source
+     * @returns {Actions}
+     */
+    addWheel: function(name, set=true) {
+      this.createSource("wheel", name);
+      if (set) {
+        this.setWheel(name);
+      }
+      return this;
+    },
+
+    /**
+     * Set the current default wheel source
+     *
+     * @param {String} name - Name of the wheel source
+     * @returns {Actions}
+     */
+    setWheel: function(name) {
+      this.setSource("wheel", name);
+      return this;
+    },
+
+    createSource: function(type, name, parameters={}) {
+      if (!this.sources.has(type)) {
+        throw new Error(`${type} is not a valid action type`);
+      }
+      let sourceNames = new Set();
+      for (let [_, name] of this.sourceOrder) {
+        sourceNames.add(name);
+      }
+      if (!name) {
+        do {
+          name = "" + sourceNameIdx++;
+        } while (sourceNames.has(name))
+      } else {
+        if (sourceNames.has(name)) {
+          throw new Error(`Alreay have a source of type ${type} named ${name}.`);
+        }
+      }
+      this.sources.get(type).set(name, new (this.sourceTypes.get(type))(parameters));
+      this.currentSources.set(type, name);
+      this.sourceOrder.push([type, name]);
+      return this.sources.get(type).get(name);
+    },
+
+    /**
+     * Insert a new actions tick
+     *
+     * @param {Number?} duration - Minimum length of the tick in ms.
+     * @returns {Actions}
+     */
+    addTick: function(duration) {
+      this.tickIdx += 1;
+      if (duration) {
+        this.pause(duration);
+      }
+      return this;
+    },
+
+    /**
+     * Add a pause to the current tick
+     *
+     * @param {Number?} duration - Minimum length of the tick in ms.
+     * @param {String} sourceType - source type
+     * @param {String?} sourceName - Named key, pointer or wheel source to use
+     *                               or null for the default key, pointer or
+     *                               wheel source
+     * @returns {Actions}
+     */
+    pause: function(duration=0, sourceType="none", {sourceName=null}={}) {
+      if (sourceType=="none")
+        this.getSource("none").addPause(this, duration);
+      else
+        this.getSource(sourceType, sourceName).addPause(this, duration);
+      return this;
+    },
+
+    /**
+     * Create a keyDown event for the current default key source
+     *
+     * @param {String} key - Key to press
+     * @param {String?} sourceName - Named key source to use or null for the default key source
+     * @returns {Actions}
+     */
+    keyDown: function(key, {sourceName=null}={}) {
+      let source = this.getSource("key", sourceName);
+      source.keyDown(this, key);
+      return this;
+    },
+
+    /**
+     * Create a keyDown event for the current default key source
+     *
+     * @param {String} key - Key to release
+     * @param {String?} sourceName - Named key source to use or null for the default key source
+     * @returns {Actions}
+     */
+    keyUp: function(key, {sourceName=null}={}) {
+      let source = this.getSource("key", sourceName);
+      source.keyUp(this, key);
+      return this;
+    },
+
+    /**
+     * Create a pointerDown event for the current default pointer source
+     *
+     * @param {String} button - Button to press
+     * @param {String?} sourceName - Named pointer source to use or null for the default
+     *                               pointer source
+     * @returns {Actions}
+     */
+    pointerDown: function({button=this.ButtonType.LEFT, sourceName=null,
+                           width, height, pressure, tangentialPressure,
+                           tiltX, tiltY, twist, altitudeAngle, azimuthAngle}={}) {
+      let source = this.getSource("pointer", sourceName);
+      source.pointerDown(this, button, width, height, pressure, tangentialPressure,
+                         tiltX, tiltY, twist, altitudeAngle, azimuthAngle);
+      return this;
+    },
+
+    /**
+     * Create a pointerUp event for the current default pointer source
+     *
+     * @param {String} button - Button to release
+     * @param {String?} sourceName - Named pointer source to use or null for the default pointer
+     *                               source
+     * @returns {Actions}
+     */
+    pointerUp: function({button=this.ButtonType.LEFT, sourceName=null}={}) {
+      let source = this.getSource("pointer", sourceName);
+      source.pointerUp(this, button);
+      return this;
+    },
+
+    /**
+     * Create a move event for the current default pointer source
+     *
+     * @param {Number} x - Destination x coordinate
+     * @param {Number} y - Destination y coordinate
+     * @param {String|Element} origin - Origin of the coordinate system.
+     *                                  Either "pointer", "viewport" or an Element
+     * @param {Number?} duration - Time in ms for the move
+     * @param {String?} sourceName - Named pointer source to use or null for the default pointer
+     *                               source
+     * @returns {Actions}
+     */
+    pointerMove: function(x, y,
+                          {origin="viewport", duration, sourceName=null,
+                           width, height, pressure, tangentialPressure,
+                           tiltX, tiltY, twist, altitudeAngle, azimuthAngle}={}) {
+      let source = this.getSource("pointer", sourceName);
+      source.pointerMove(this, x, y, duration, origin, width, height, pressure,
+                         tangentialPressure, tiltX, tiltY, twist, altitudeAngle,
+                         azimuthAngle);
+      return this;
+    },
+
+    /**
+     * Create a scroll event for the current default wheel source
+     *
+     * @param {Number} x - mouse cursor x coordinate
+     * @param {Number} y - mouse cursor y coordinate
+     * @param {Number} deltaX - scroll delta value along the x-axis in pixels
+     * @param {Number} deltaY - scroll delta value along the y-axis in pixels
+     * @param {String|Element} origin - Origin of the coordinate system.
+     *                                  Either "viewport" or an Element
+     * @param {Number?} duration - Time in ms for the scroll
+     * @param {String?} sourceName - Named wheel source to use or null for the
+     *                               default wheel source
+     * @returns {Actions}
+     */
+    scroll: function(x, y, deltaX, deltaY,
+                     {origin="viewport", duration, sourceName=null}={}) {
+      let source = this.getSource("wheel", sourceName);
+      source.scroll(this, x, y, deltaX, deltaY, duration, origin);
+      return this;
+    },
+  };
+
+  function GeneralSource() {
+    this.actions = new Map();
+  }
+
+  GeneralSource.prototype = {
+    serialize: function(tickCount, defaultTickDuration) {
+      let actions = [];
+      let data = {"type": "none", "actions": actions};
+      for (let i=0; i<tickCount; i++) {
+        if (this.actions.has(i)) {
+          actions.push(this.actions.get(i));
+        } else {
+          actions.push({"type": "pause", duration: defaultTickDuration});
+        }
+      }
+      return data;
+    },
+
+    addPause: function(actions, duration) {
+      let tick = actions.tickIdx;
+      if (this.actions.has(tick)) {
+        throw new Error(`Already have a pause action for the current tick`);
+      }
+      this.actions.set(tick, {type: "pause", duration: duration});
+    },
+  };
+
+  function KeySource() {
+    this.actions = new Map();
+  }
+
+  KeySource.prototype = {
+    serialize: function(tickCount) {
+      if (!this.actions.size) {
+        return undefined;
+      }
+      let actions = [];
+      let data = {"type": "key", "actions": actions};
+      for (let i=0; i<tickCount; i++) {
+        if (this.actions.has(i)) {
+          actions.push(this.actions.get(i));
+        } else {
+          actions.push({"type": "pause"});
+        }
+      }
+      return data;
+    },
+
+    keyDown: function(actions, key) {
+      let tick = actions.tickIdx;
+      if (this.actions.has(tick)) {
+        tick = actions.addTick().tickIdx;
+      }
+      this.actions.set(tick, {type: "keyDown", value: key});
+    },
+
+    keyUp: function(actions, key) {
+      let tick = actions.tickIdx;
+      if (this.actions.has(tick)) {
+        tick = actions.addTick().tickIdx;
+      }
+      this.actions.set(tick, {type: "keyUp", value: key});
+    },
+
+    addPause: function(actions, duration) {
+      let tick = actions.tickIdx;
+      if (this.actions.has(tick)) {
+        tick = actions.addTick().tickIdx;
+      }
+      this.actions.set(tick, {type: "pause", duration: duration});
+    },
+  };
+
+  function PointerSource(parameters={pointerType: "mouse"}) {
+    let pointerType = parameters.pointerType || "mouse";
+    if (!["mouse", "pen", "touch"].includes(pointerType)) {
+      throw new Error(`Invalid pointerType ${pointerType}`);
+    }
+    this.type = pointerType;
+    this.actions = new Map();
+  }
+
+  function setPointerProperties(action, width, height, pressure, tangentialPressure,
+                                tiltX, tiltY, twist, altitudeAngle, azimuthAngle) {
+    if (width) {
+      action.width = width;
+    }
+    if (height) {
+      action.height = height;
+    }
+    if (pressure) {
+      action.pressure = pressure;
+    }
+    if (tangentialPressure) {
+      action.tangentialPressure = tangentialPressure;
+    }
+    if (tiltX) {
+      action.tiltX = tiltX;
+    }
+    if (tiltY) {
+      action.tiltY = tiltY;
+    }
+    if (twist) {
+      action.twist = twist;
+    }
+    if (altitudeAngle) {
+      action.altitudeAngle = altitudeAngle;
+    }
+    if (azimuthAngle) {
+      action.azimuthAngle = azimuthAngle;
+    }
+    return action;
+  }
+
+  PointerSource.prototype = {
+    serialize: function(tickCount) {
+      if (!this.actions.size) {
+        return undefined;
+      }
+      let actions = [];
+      let data = {"type": "pointer", "actions": actions, "parameters": {"pointerType": this.type}};
+      for (let i=0; i<tickCount; i++) {
+        if (this.actions.has(i)) {
+          actions.push(this.actions.get(i));
+        } else {
+          actions.push({"type": "pause"});
+        }
+      }
+      return data;
+    },
+
+    pointerDown: function(actions, button, width, height, pressure, tangentialPressure,
+                          tiltX, tiltY, twist, altitudeAngle, azimuthAngle) {
+      let tick = actions.tickIdx;
+      if (this.actions.has(tick)) {
+        tick = actions.addTick().tickIdx;
+      }
+      let actionProperties = setPointerProperties({type: "pointerDown", button}, width, height,
+                                                  pressure, tangentialPressure, tiltX, tiltY,
+                                                  twist, altitudeAngle, azimuthAngle);
+      this.actions.set(tick, actionProperties);
+    },
+
+    pointerUp: function(actions, button) {
+      let tick = actions.tickIdx;
+      if (this.actions.has(tick)) {
+        tick = actions.addTick().tickIdx;
+      }
+      this.actions.set(tick, {type: "pointerUp", button});
+    },
+
+    pointerMove: function(actions, x, y, duration, origin, width, height, pressure,
+                          tangentialPressure, tiltX, tiltY, twist, altitudeAngle, azimuthAngle) {
+      let tick = actions.tickIdx;
+      if (this.actions.has(tick)) {
+        tick = actions.addTick().tickIdx;
+      }
+      let moveAction = {type: "pointerMove", x, y, origin};
+      if (duration) {
+        moveAction.duration = duration;
+      }
+      let actionProperties = setPointerProperties(moveAction, width, height, pressure,
+                                                  tangentialPressure, tiltX, tiltY, twist,
+                                                  altitudeAngle, azimuthAngle);
+      this.actions.set(tick, actionProperties);
+    },
+
+    addPause: function(actions, duration) {
+      let tick = actions.tickIdx;
+      if (this.actions.has(tick)) {
+        tick = actions.addTick().tickIdx;
+      }
+      this.actions.set(tick, {type: "pause", duration: duration});
+    },
+  };
+
+  function WheelSource() {
+    this.actions = new Map();
+  }
+
+  WheelSource.prototype = {
+    serialize: function(tickCount) {
+      if (!this.actions.size) {
+        return undefined;
+      }
+      let actions = [];
+      let data = {"type": "wheel", "actions": actions};
+      for (let i=0; i<tickCount; i++) {
+        if (this.actions.has(i)) {
+          actions.push(this.actions.get(i));
+        } else {
+          actions.push({"type": "pause"});
+        }
+      }
+      return data;
+    },
+
+    scroll: function(actions, x, y, deltaX, deltaY, duration, origin) {
+      let tick = actions.tickIdx;
+      if (this.actions.has(tick)) {
+        tick = actions.addTick().tickIdx;
+      }
+      this.actions.set(tick, {type: "scroll", x, y, deltaX, deltaY, origin});
+      if (duration) {
+        this.actions.get(tick).duration = duration;
+      }
+    },
+
+    addPause: function(actions, duration) {
+      let tick = actions.tickIdx;
+      if (this.actions.has(tick)) {
+        tick = actions.addTick().tickIdx;
+      }
+      this.actions.set(tick, {type: "pause", duration: duration});
+    },
+  };
+
+  test_driver.Actions = Actions;
+})();
diff --git a/test/wpt/tests/resources/testdriver-vendor.js b/test/wpt/tests/resources/testdriver-vendor.js
new file mode 100644
index 0000000..e69de29
--- /dev/null
+++ b/test/wpt/tests/resources/testdriver-vendor.js
diff --git a/test/wpt/tests/resources/testdriver-vendor.js.headers b/test/wpt/tests/resources/testdriver-vendor.js.headers
new file mode 100644
index 0000000..5e8f640
--- /dev/null
+++ b/test/wpt/tests/resources/testdriver-vendor.js.headers
@@ -0,0 +1,2 @@
+Content-Type: text/javascript; charset=utf-8
+Cache-Control: max-age=3600
diff --git a/test/wpt/tests/resources/testdriver.js b/test/wpt/tests/resources/testdriver.js
new file mode 100644
index 0000000..a23d6ea
--- /dev/null
+++ b/test/wpt/tests/resources/testdriver.js
@@ -0,0 +1,958 @@
+(function() {
+    "use strict";
+    var idCounter = 0;
+    let testharness_context = null;
+
+    function getInViewCenterPoint(rect) {
+        var left = Math.max(0, rect.left);
+        var right = Math.min(window.innerWidth, rect.right);
+        var top = Math.max(0, rect.top);
+        var bottom = Math.min(window.innerHeight, rect.bottom);
+
+        var x = 0.5 * (left + right);
+        var y = 0.5 * (top + bottom);
+
+        return [x, y];
+    }
+
+    function getPointerInteractablePaintTree(element) {
+        let elementDocument = element.ownerDocument;
+        if (!elementDocument.contains(element)) {
+            return [];
+        }
+
+        var rectangles = element.getClientRects();
+
+        if (rectangles.length === 0) {
+            return [];
+        }
+
+        var centerPoint = getInViewCenterPoint(rectangles[0]);
+
+        if ("elementsFromPoint" in elementDocument) {
+            return elementDocument.elementsFromPoint(centerPoint[0], centerPoint[1]);
+        } else if ("msElementsFromPoint" in elementDocument) {
+            var rv = elementDocument.msElementsFromPoint(centerPoint[0], centerPoint[1]);
+            return Array.prototype.slice.call(rv ? rv : []);
+        } else {
+            throw new Error("document.elementsFromPoint unsupported");
+        }
+    }
+
+    function inView(element) {
+        var pointerInteractablePaintTree = getPointerInteractablePaintTree(element);
+        return pointerInteractablePaintTree.indexOf(element) !== -1;
+    }
+
+
+    /**
+     * @namespace {test_driver}
+     */
+    window.test_driver = {
+        /**
+         * Set the context in which testharness.js is loaded
+         *
+         * @param {WindowProxy} context - the window containing testharness.js
+         **/
+        set_test_context: function(context) {
+          if (window.test_driver_internal.set_test_context) {
+            window.test_driver_internal.set_test_context(context);
+          }
+          testharness_context = context;
+        },
+
+        /**
+         * postMessage to the context containing testharness.js
+         *
+         * @param {Object} msg - the data to POST
+         **/
+        message_test: function(msg) {
+            let target = testharness_context;
+            if (testharness_context === null) {
+                target = window;
+            }
+            target.postMessage(msg, "*");
+        },
+
+        /**
+         * Trigger user interaction in order to grant additional privileges to
+         * a provided function.
+         *
+         * See `Tracking user activation
+         * <https://html.spec.whatwg.org/multipage/interaction.html#tracking-user-activation>`_.
+         *
+         * @example
+         * var mediaElement = document.createElement('video');
+         *
+         * test_driver.bless('initiate media playback', function () {
+         *   mediaElement.play();
+         * });
+         *
+         * @param {String} intent - a description of the action which must be
+         *                          triggered by user interaction
+         * @param {Function} action - code requiring escalated privileges
+         * @param {WindowProxy} context - Browsing context in which
+         *                                to run the call, or null for the current
+         *                                browsing context.
+         *
+         * @returns {Promise} fulfilled following user interaction and
+         *                    execution of the provided `action` function;
+         *                    rejected if interaction fails or the provided
+         *                    function throws an error
+         */
+        bless: function(intent, action, context=null) {
+            let contextDocument = context ? context.document : document;
+            var button = contextDocument.createElement("button");
+            button.innerHTML = "This test requires user interaction.<br />" +
+                "Please click here to allow " + intent + ".";
+            button.id = "wpt-test-driver-bless-" + (idCounter += 1);
+            const elem = contextDocument.body || contextDocument.documentElement;
+            elem.appendChild(button);
+
+            let wait_click = new Promise(resolve => button.addEventListener("click", resolve));
+
+            return test_driver.click(button)
+                .then(wait_click)
+                .then(function() {
+                    button.remove();
+
+                    if (typeof action === "function") {
+                        return action();
+                    }
+                    return null;
+                });
+        },
+
+        /**
+         * Triggers a user-initiated click
+         *
+         * If ``element`` isn't inside the
+         * viewport, it will be scrolled into view before the click
+         * occurs.
+         *
+         * If ``element`` is from a different browsing context, the
+         * command will be run in that context.
+         *
+         * Matches the behaviour of the `Element Click
+         * <https://w3c.github.io/webdriver/#element-click>`_
+         * WebDriver command.
+         *
+         * **Note:** If the element to be clicked does not have a
+         * unique ID, the document must not have any DOM mutations
+         * made between the function being called and the promise
+         * settling.
+         *
+         * @param {Element} element - element to be clicked
+         * @returns {Promise} fulfilled after click occurs, or rejected in
+         *                    the cases the WebDriver command errors
+         */
+        click: function(element) {
+            if (!inView(element)) {
+                element.scrollIntoView({behavior: "instant",
+                                        block: "end",
+                                        inline: "nearest"});
+            }
+
+            var pointerInteractablePaintTree = getPointerInteractablePaintTree(element);
+            if (pointerInteractablePaintTree.length === 0 ||
+                !element.contains(pointerInteractablePaintTree[0])) {
+                return Promise.reject(new Error("element click intercepted error"));
+            }
+
+            var rect = element.getClientRects()[0];
+            var centerPoint = getInViewCenterPoint(rect);
+            return window.test_driver_internal.click(element,
+                                                     {x: centerPoint[0],
+                                                      y: centerPoint[1]});
+        },
+
+        /**
+         * Deletes all cookies.
+         *
+         * Matches the behaviour of the `Delete All Cookies
+         * <https://w3c.github.io/webdriver/#delete-all-cookies>`_
+         * WebDriver command.
+         *
+         * @param {WindowProxy} context - Browsing context in which
+         *                                to run the call, or null for the current
+         *                                browsing context.
+         *
+         * @returns {Promise} fulfilled after cookies are deleted, or rejected in
+         *                    the cases the WebDriver command errors
+         */
+        delete_all_cookies: function(context=null) {
+            return window.test_driver_internal.delete_all_cookies(context);
+        },
+
+        /**
+         * Get details for all cookies in the current context.
+         * See https://w3c.github.io/webdriver/#get-all-cookies
+         *
+         * @param {WindowProxy} context - Browsing context in which
+         *                                to run the call, or null for the current
+         *                                browsing context.
+         *
+         * @returns {Promise} Returns an array of cookies objects as defined in the spec:
+         *                    https://w3c.github.io/webdriver/#cookies
+         */
+        get_all_cookies: function(context=null) {
+            return window.test_driver_internal.get_all_cookies(context);
+        },
+
+        /**
+         * Get details for a cookie in the current context by name if it exists.
+         * See https://w3c.github.io/webdriver/#get-named-cookie
+         *
+         * @param {String} name - The name of the cookie to get.
+         * @param {WindowProxy} context - Browsing context in which
+         *                                to run the call, or null for the current
+         *                                browsing context.
+         *
+         * @returns {Promise} Returns the matching cookie as defined in the spec:
+         *                    https://w3c.github.io/webdriver/#cookies
+         *                    Rejected if no such cookie exists.
+         */
+         get_named_cookie: async function(name, context=null) {
+            let cookie = await window.test_driver_internal.get_named_cookie(name, context);
+            if (!cookie) {
+                throw new Error("no such cookie");
+            }
+            return cookie;
+        },
+
+        /**
+         * Get Computed Label for an element.
+         *
+         * This matches the behaviour of the
+         * `Get Computed Label
+         * <https://w3c.github.io/webdriver/#dfn-get-computed-label>`_
+         * WebDriver command.
+         *
+         * @param {Element} element
+         * @returns {Promise} fulfilled after the computed label is returned, or
+         *                    rejected in the cases the WebDriver command errors
+         */
+        get_computed_label: async function(element) {
+            let label = await window.test_driver_internal.get_computed_label(element);
+            return label;
+        },
+
+        /**
+         * Get Computed Role for an element.
+         *
+         * This matches the behaviour of the
+         * `Get Computed Label
+         * <https://w3c.github.io/webdriver/#dfn-get-computed-role>`_
+         * WebDriver command.
+         *
+         * @param {Element} element
+         * @returns {Promise} fulfilled after the computed role is returned, or
+         *                    rejected in the cases the WebDriver command errors
+         */
+        get_computed_role: async function(element) {
+            let role = await window.test_driver_internal.get_computed_role(element);
+            return role;
+        },
+
+        /**
+         * Send keys to an element.
+         *
+         * If ``element`` isn't inside the
+         * viewport, it will be scrolled into view before the click
+         * occurs.
+         *
+         * If ``element`` is from a different browsing context, the
+         * command will be run in that context.
+         *
+         * To send special keys, send the respective key's codepoint,
+         * as defined by `WebDriver
+         * <https://w3c.github.io/webdriver/#keyboard-actions>`_.  For
+         * example, the "tab" key is represented as "``\uE004``".
+         *
+         * **Note:** these special-key codepoints are not necessarily
+         * what you would expect. For example, <kbd>Esc</kbd> is the
+         * invalid Unicode character ``\uE00C``, not the ``\u001B`` Escape
+         * character from ASCII.
+         *
+         * This matches the behaviour of the
+         * `Send Keys
+         * <https://w3c.github.io/webdriver/#element-send-keys>`_
+         * WebDriver command.
+         *
+         * **Note:** If the element to be clicked does not have a
+         * unique ID, the document must not have any DOM mutations
+         * made between the function being called and the promise
+         * settling.
+         *
+         * @param {Element} element - element to send keys to
+         * @param {String} keys - keys to send to the element
+         * @returns {Promise} fulfilled after keys are sent, or rejected in
+         *                    the cases the WebDriver command errors
+         */
+        send_keys: function(element, keys) {
+            if (!inView(element)) {
+                element.scrollIntoView({behavior: "instant",
+                                        block: "end",
+                                        inline: "nearest"});
+            }
+
+            return window.test_driver_internal.send_keys(element, keys);
+        },
+
+        /**
+         * Freeze the current page
+         *
+         * The freeze function transitions the page from the HIDDEN state to
+         * the FROZEN state as described in `Lifecycle API for Web Pages
+         * <https://github.com/WICG/page-lifecycle/blob/master/README.md>`_.
+         *
+         * @param {WindowProxy} context - Browsing context in which
+         *                                to run the call, or null for the current
+         *                                browsing context.
+         *
+         * @returns {Promise} fulfilled after the freeze request is sent, or rejected
+         *                    in case the WebDriver command errors
+         */
+        freeze: function(context=null) {
+            return window.test_driver_internal.freeze();
+        },
+
+        /**
+         * Minimizes the browser window.
+         *
+         * Matches the the behaviour of the `Minimize
+         * <https://www.w3.org/TR/webdriver/#minimize-window>`_
+         * WebDriver command
+         *
+         * @param {WindowProxy} context - Browsing context in which
+         *                                to run the call, or null for the current
+         *                                browsing context.
+         *
+         * @returns {Promise} fulfilled with the previous `WindowRect
+         *                    <https://www.w3.org/TR/webdriver/#dfn-windowrect-object>`_
+         *                    value, after the window is minimized.
+         */
+        minimize_window: function(context=null) {
+            return window.test_driver_internal.minimize_window(context);
+        },
+
+        /**
+         * Restore the window from minimized/maximized state to a given rect.
+         *
+         * Matches the behaviour of the `Set Window Rect
+         * <https://www.w3.org/TR/webdriver/#set-window-rect>`_
+         * WebDriver command
+         *
+         * @param {Object} rect - A `WindowRect
+         *                        <https://www.w3.org/TR/webdriver/#dfn-windowrect-object>`_
+         * @param {WindowProxy} context - Browsing context in which
+         *                                to run the call, or null for the current
+         *                                browsing context.
+         *
+         * @returns {Promise} fulfilled after the window is restored to the given rect.
+         */
+        set_window_rect: function(rect, context=null) {
+            return window.test_driver_internal.set_window_rect(rect, context);
+        },
+
+        /**
+         * Send a sequence of actions
+         *
+         * This function sends a sequence of actions to perform.
+         *
+         * Matches the behaviour of the `Actions
+         * <https://w3c.github.io/webdriver/#actions>`_ feature in
+         * WebDriver.
+         *
+         * Authors are encouraged to use the
+         * :js:class:`test_driver.Actions` builder rather than
+         * invoking this API directly.
+         *
+         * @param {Array} actions - an array of actions. The format is
+         *                          the same as the actions property
+         *                          of the `Perform Actions
+         *                          <https://w3c.github.io/webdriver/#perform-actions>`_
+         *                          WebDriver command. Each element is
+         *                          an object representing an input
+         *                          source and each input source
+         *                          itself has an actions property
+         *                          detailing the behaviour of that
+         *                          source at each timestep (or
+         *                          tick). Authors are not expected to
+         *                          construct the actions sequence by
+         *                          hand, but to use the builder api
+         *                          provided in testdriver-actions.js
+         * @param {WindowProxy} context - Browsing context in which
+         *                                to run the call, or null for the current
+         *                                browsing context.
+         *
+         * @returns {Promise} fulfilled after the actions are performed, or rejected in
+         *                    the cases the WebDriver command errors
+         */
+        action_sequence: function(actions, context=null) {
+            return window.test_driver_internal.action_sequence(actions, context);
+        },
+
+        /**
+         * Generates a test report on the current page
+         *
+         * The generate_test_report function generates a report (to be
+         * observed by ReportingObserver) for testing purposes.
+         *
+         * Matches the `Generate Test Report
+         * <https://w3c.github.io/reporting/#generate-test-report-command>`_
+         * WebDriver command.
+         *
+         * @param {WindowProxy} context - Browsing context in which
+         *                                to run the call, or null for the current
+         *                                browsing context.
+         *
+         * @returns {Promise} fulfilled after the report is generated, or
+         *                    rejected if the report generation fails
+         */
+        generate_test_report: function(message, context=null) {
+            return window.test_driver_internal.generate_test_report(message, context);
+        },
+
+        /**
+         * Sets the state of a permission
+         *
+         * This function simulates a user setting a permission into a
+         * particular state.
+         *
+         * Matches the `Set Permission
+         * <https://w3c.github.io/permissions/#set-permission-command>`_
+         * WebDriver command.
+         *
+         * @example
+         * await test_driver.set_permission({ name: "background-fetch" }, "denied");
+         * await test_driver.set_permission({ name: "push", userVisibleOnly: true }, "granted");
+         *
+         * @param {PermissionDescriptor} descriptor - a `PermissionDescriptor
+         *                              <https://w3c.github.io/permissions/#dom-permissiondescriptor>`_
+         *                              dictionary.
+         * @param {String} state - the state of the permission
+         * @param {WindowProxy} context - Browsing context in which
+         *                                to run the call, or null for the current
+         *                                browsing context.
+         * @returns {Promise} fulfilled after the permission is set, or rejected if setting the
+         *                    permission fails
+         */
+        set_permission: function(descriptor, state, context=null) {
+            let permission_params = {
+              descriptor,
+              state,
+            };
+            return window.test_driver_internal.set_permission(permission_params, context);
+        },
+
+        /**
+         * Creates a virtual authenticator
+         *
+         * This function creates a virtual authenticator for use with
+         * the U2F and WebAuthn APIs.
+         *
+         * Matches the `Add Virtual Authenticator
+         * <https://w3c.github.io/webauthn/#sctn-automation-add-virtual-authenticator>`_
+         * WebDriver command.
+         *
+         * @param {Object} config - an `Authenticator Configuration
+         *                          <https://w3c.github.io/webauthn/#authenticator-configuration>`_
+         *                          object
+         * @param {WindowProxy} context - Browsing context in which
+         *                                to run the call, or null for the current
+         *                                browsing context.
+         *
+         * @returns {Promise} fulfilled after the authenticator is added, or
+         *                    rejected in the cases the WebDriver command
+         *                    errors. Returns the ID of the authenticator
+         */
+        add_virtual_authenticator: function(config, context=null) {
+            return window.test_driver_internal.add_virtual_authenticator(config, context);
+        },
+
+        /**
+         * Removes a virtual authenticator
+         *
+         * This function removes a virtual authenticator that has been
+         * created by :js:func:`add_virtual_authenticator`.
+         *
+         * Matches the `Remove Virtual Authenticator
+         * <https://w3c.github.io/webauthn/#sctn-automation-remove-virtual-authenticator>`_
+         * WebDriver command.
+         *
+         * @param {String} authenticator_id - the ID of the authenticator to be
+         *                                    removed.
+         * @param {WindowProxy} context - Browsing context in which
+         *                                to run the call, or null for the current
+         *                                browsing context.
+         *
+         * @returns {Promise} fulfilled after the authenticator is removed, or
+         *                    rejected in the cases the WebDriver command
+         *                    errors
+         */
+        remove_virtual_authenticator: function(authenticator_id, context=null) {
+            return window.test_driver_internal.remove_virtual_authenticator(authenticator_id, context);
+        },
+
+        /**
+         * Adds a credential to a virtual authenticator
+         *
+         * Matches the `Add Credential
+         * <https://w3c.github.io/webauthn/#sctn-automation-add-credential>`_
+         * WebDriver command.
+         *
+         * @param {String} authenticator_id - the ID of the authenticator
+         * @param {Object} credential - A `Credential Parameters
+         *                              <https://w3c.github.io/webauthn/#credential-parameters>`_
+         *                              object
+         * @param {WindowProxy} context - Browsing context in which
+         *                                to run the call, or null for the current
+         *                                browsing context.
+         *
+         * @returns {Promise} fulfilled after the credential is added, or
+         *                    rejected in the cases the WebDriver command
+         *                    errors
+         */
+        add_credential: function(authenticator_id, credential, context=null) {
+            return window.test_driver_internal.add_credential(authenticator_id, credential, context);
+        },
+
+        /**
+         * Gets all the credentials stored in an authenticator
+         *
+         * This function retrieves all the credentials (added via the U2F API,
+         * WebAuthn, or the add_credential function) stored in a virtual
+         * authenticator
+         *
+         * Matches the `Get Credentials
+         * <https://w3c.github.io/webauthn/#sctn-automation-get-credentials>`_
+         * WebDriver command.
+         *
+         * @param {String} authenticator_id - the ID of the authenticator
+         * @param {WindowProxy} context - Browsing context in which
+         *                                to run the call, or null for the current
+         *                                browsing context.
+         *
+         * @returns {Promise} fulfilled after the credentials are
+         *                    returned, or rejected in the cases the
+         *                    WebDriver command errors. Returns an
+         *                    array of `Credential Parameters
+         *                    <https://w3c.github.io/webauthn/#credential-parameters>`_
+         */
+        get_credentials: function(authenticator_id, context=null) {
+            return window.test_driver_internal.get_credentials(authenticator_id, context=null);
+        },
+
+        /**
+         * Remove a credential stored in an authenticator
+         *
+         * Matches the `Remove Credential
+         * <https://w3c.github.io/webauthn/#sctn-automation-remove-credential>`_
+         * WebDriver command.
+         *
+         * @param {String} authenticator_id - the ID of the authenticator
+         * @param {String} credential_id - the ID of the credential
+         * @param {WindowProxy} context - Browsing context in which
+         *                                to run the call, or null for the current
+         *                                browsing context.
+         *
+         * @returns {Promise} fulfilled after the credential is removed, or
+         *                    rejected in the cases the WebDriver command
+         *                    errors.
+         */
+        remove_credential: function(authenticator_id, credential_id, context=null) {
+            return window.test_driver_internal.remove_credential(authenticator_id, credential_id, context);
+        },
+
+        /**
+         * Removes all the credentials stored in a virtual authenticator
+         *
+         * Matches the `Remove All Credentials
+         * <https://w3c.github.io/webauthn/#sctn-automation-remove-all-credentials>`_
+         * WebDriver command.
+         *
+         * @param {String} authenticator_id - the ID of the authenticator
+         * @param {WindowProxy} context - Browsing context in which
+         *                                to run the call, or null for the current
+         *                                browsing context.
+         *
+         * @returns {Promise} fulfilled after the credentials are removed, or
+         *                    rejected in the cases the WebDriver command
+         *                    errors.
+         */
+        remove_all_credentials: function(authenticator_id, context=null) {
+            return window.test_driver_internal.remove_all_credentials(authenticator_id, context);
+        },
+
+        /**
+         * Sets the User Verified flag on an authenticator
+         *
+         * Sets whether requests requiring user verification will succeed or
+         * fail on a given virtual authenticator
+         *
+         * Matches the `Set User Verified
+         * <https://w3c.github.io/webauthn/#sctn-automation-set-user-verified>`_
+         * WebDriver command.
+         *
+         * @param {String} authenticator_id - the ID of the authenticator
+         * @param {boolean} uv - the User Verified flag
+         * @param {WindowProxy} context - Browsing context in which
+         *                                to run the call, or null for the current
+         *                                browsing context.
+         */
+        set_user_verified: function(authenticator_id, uv, context=null) {
+            return window.test_driver_internal.set_user_verified(authenticator_id, uv, context);
+        },
+
+        /**
+         * Sets the storage access rule for an origin when embedded
+         * in a third-party context.
+         *
+         * Matches the `Set Storage Access
+         * <https://privacycg.github.io/storage-access/#set-storage-access-command>`_
+         * WebDriver command.
+         *
+         * @param {String} origin - A third-party origin to block or allow.
+         *                          May be "*" to indicate all origins.
+         * @param {String} embedding_origin - an embedding (first-party) origin
+         *                                    on which {origin}'s access should
+         *                                    be blocked or allowed.
+         *                                    May be "*" to indicate all origins.
+         * @param {String} state - The storage access setting.
+         *                         Must be either "allowed" or "blocked".
+         * @param {WindowProxy} context - Browsing context in which
+         *                                to run the call, or null for the current
+         *                                browsing context.
+         *
+         * @returns {Promise} Fulfilled after the storage access rule has been
+         *                    set, or rejected if setting the rule fails.
+         */
+        set_storage_access: function(origin, embedding_origin, state, context=null) {
+            if (state !== "allowed" && state !== "blocked") {
+                throw new Error("storage access status must be 'allowed' or 'blocked'");
+            }
+            const blocked = state === "blocked";
+            return window.test_driver_internal.set_storage_access(origin, embedding_origin, blocked, context);
+        },
+
+        /**
+         * Sets the current transaction automation mode for Secure Payment
+         * Confirmation.
+         *
+         * This function places `Secure Payment
+         * Confirmation <https://w3c.github.io/secure-payment-confirmation>`_ into
+         * an automated 'autoaccept' or 'autoreject' mode, to allow testing
+         * without user interaction with the transaction UX prompt.
+         *
+         * Matches the `Set SPC Transaction Mode
+         * <https://w3c.github.io/secure-payment-confirmation/#sctn-automation-set-spc-transaction-mode>`_
+         * WebDriver command.
+         *
+         * @example
+         * await test_driver.set_spc_transaction_mode("autoaccept");
+         * test.add_cleanup(() => {
+         *   return test_driver.set_spc_transaction_mode("none");
+         * });
+         *
+         * // Assumption: `request` is a PaymentRequest with a secure-payment-confirmation
+         * // payment method.
+         * const response = await request.show();
+         *
+         * @param {String} mode - The `transaction mode
+         *                        <https://w3c.github.io/secure-payment-confirmation/#enumdef-transactionautomationmode>`_
+         *                        to set. Must be one of "``none``",
+         *                        "``autoaccept``", or
+         *                        "``autoreject``".
+         * @param {WindowProxy} context - Browsing context in which
+         *                                to run the call, or null for the current
+         *                                browsing context.
+         *
+         * @returns {Promise} Fulfilled after the transaction mode has been set,
+         *                    or rejected if setting the mode fails.
+         */
+        set_spc_transaction_mode: function(mode, context=null) {
+          return window.test_driver_internal.set_spc_transaction_mode(mode, context);
+        },
+
+        /**
+         * Cancels the Federated Credential Management dialog
+         *
+         * Matches the `Cancel dialog
+         * <https://fedidcg.github.io/FedCM/#webdriver-canceldialog>`_
+         * WebDriver command.
+         *
+         * @param {WindowProxy} context - Browsing context in which
+         *                                to run the call, or null for the current
+         *                                browsing context.
+         *
+         * @returns {Promise} Fulfilled after the dialog is canceled, or rejected
+         *                    in case the WebDriver command errors
+         */
+        cancel_fedcm_dialog: function(context=null) {
+            return window.test_driver_internal.cancel_fedcm_dialog(context);
+        },
+
+        /**
+         * Selects an account from the Federated Credential Management dialog
+         *
+         * Matches the `Select account
+         * <https://fedidcg.github.io/FedCM/#webdriver-selectaccount>`_
+         * WebDriver command.
+         *
+         * @param {number} account_index - Index of the account to select.
+         * @param {WindowProxy} context - Browsing context in which
+         *                                to run the call, or null for the current
+         *                                browsing context.
+         *
+         * @returns {Promise} Fulfilled after the account is selected,
+         *                    or rejected in case the WebDriver command errors
+         */
+        select_fedcm_account: function(account_index, context=null) {
+          return window.test_driver_internal.select_fedcm_account(account_index, context);
+        },
+
+        /**
+         * Gets the account list from the Federated Credential Management dialog
+         *
+         * Matches the `Account list
+         * <https://fedidcg.github.io/FedCM/#webdriver-accountlist>`_
+         * WebDriver command.
+         *
+         * @param {WindowProxy} context - Browsing context in which
+         *                                to run the call, or null for the current
+         *                                browsing context.
+         *
+         * @returns {Promise} fulfilled after the account list is returned, or
+         *                    rejected in case the WebDriver command errors
+         */
+        get_fedcm_account_list: function(context=null) {
+          return window.test_driver_internal.get_fedcm_account_list(context);
+        },
+
+        /**
+         * Gets the title of the Federated Credential Management dialog
+         *
+         * Matches the `Get title
+         * <https://fedidcg.github.io/FedCM/#webdriver-gettitle>`_
+         * WebDriver command.
+         *
+         * @param {WindowProxy} context - Browsing context in which
+         *                                to run the call, or null for the current
+         *                                browsing context.
+         *
+         * @returns {Promise} Fulfilled after the title is returned, or rejected
+         *                    in case the WebDriver command errors
+         */
+        get_fedcm_dialog_title: function(context=null) {
+          return window.test_driver_internal.get_fedcm_dialog_title(context);
+        },
+
+        /**
+         * Gets the type of the Federated Credential Management dialog
+         *
+         * Matches the `Get dialog type
+         * <https://fedidcg.github.io/FedCM/#webdriver-getdialogtype>`_
+         * WebDriver command.
+         *
+         * @param {WindowProxy} context - Browsing context in which
+         *                                to run the call, or null for the current
+         *                                browsing context.
+         *
+         * @returns {Promise} Fulfilled after the dialog type is returned, or
+         *                    rejected in case the WebDriver command errors
+         */
+        get_fedcm_dialog_type: function(context=null) {
+          return window.test_driver_internal.get_fedcm_dialog_type(context);
+        },
+
+        /**
+         * Sets whether promise rejection delay is enabled for the Federated Credential Management dialog
+         *
+         * Matches the `Set delay enabled
+         * <https://fedidcg.github.io/FedCM/#webdriver-setdelayenabled>`_
+         * WebDriver command.
+         *
+         * @param {boolean} enabled - Whether to delay FedCM promise rejection.
+         * @param {WindowProxy} context - Browsing context in which
+         *                                to run the call, or null for the current
+         *                                browsing context.
+         *
+         * @returns {Promise} Fulfilled after the delay has been enabled or disabled,
+         *                    or rejected in case the WebDriver command errors
+         */
+        set_fedcm_delay_enabled: function(enabled, context=null) {
+          return window.test_driver_internal.set_fedcm_delay_enabled(enabled, context);
+        },
+
+        /**
+         * Resets the Federated Credential Management dialog's cooldown
+         *
+         * Matches the `Reset cooldown
+         * <https://fedidcg.github.io/FedCM/#webdriver-resetcooldown>`_
+         * WebDriver command.
+         *
+         * @param {WindowProxy} context - Browsing context in which
+         *                                to run the call, or null for the current
+         *                                browsing context.
+         *
+         * @returns {Promise} Fulfilled after the cooldown has been reset,
+         *                    or rejected in case the WebDriver command errors
+         */
+        reset_fedcm_cooldown: function(context=null) {
+          return window.test_driver_internal.reset_fedcm_cooldown(context);
+        }
+    };
+
+    window.test_driver_internal = {
+        /**
+         * This flag should be set to `true` by any code which implements the
+         * internal methods defined below for automation purposes. Doing so
+         * allows the library to signal failure immediately when an automated
+         * implementation of one of the methods is not available.
+         */
+        in_automation: false,
+
+        async click(element, coords) {
+            if (this.in_automation) {
+                throw new Error("click() is not implemented by testdriver-vendor.js");
+            }
+
+            return new Promise(function(resolve, reject) {
+                element.addEventListener("click", resolve);
+            });
+        },
+
+        async delete_all_cookies(context=null) {
+            throw new Error("delete_all_cookies() is not implemented by testdriver-vendor.js");
+        },
+
+        async get_all_cookies(context=null) {
+            throw new Error("get_all_cookies() is not implemented by testdriver-vendor.js");
+        },
+
+        async get_named_cookie(name, context=null) {
+            throw new Error("get_named_cookie() is not implemented by testdriver-vendor.js");
+        },
+
+        async send_keys(element, keys) {
+            if (this.in_automation) {
+                throw new Error("send_keys() is not implemented by testdriver-vendor.js");
+            }
+
+            return new Promise(function(resolve, reject) {
+                var seen = "";
+
+                function remove() {
+                    element.removeEventListener("keydown", onKeyDown);
+                }
+
+                function onKeyDown(event) {
+                    if (event.key.length > 1) {
+                        return;
+                    }
+
+                    seen += event.key;
+
+                    if (keys.indexOf(seen) !== 0) {
+                        reject(new Error("Unexpected key sequence: " + seen));
+                        remove();
+                    } else if (seen === keys) {
+                        resolve();
+                        remove();
+                    }
+                }
+
+                element.addEventListener("keydown", onKeyDown);
+            });
+        },
+
+        async freeze(context=null) {
+            throw new Error("freeze() is not implemented by testdriver-vendor.js");
+        },
+
+        async minimize_window(context=null) {
+            throw new Error("minimize_window() is not implemented by testdriver-vendor.js");
+        },
+
+        async set_window_rect(rect, context=null) {
+            throw new Error("set_window_rect() is not implemented by testdriver-vendor.js");
+        },
+
+        async action_sequence(actions, context=null) {
+            throw new Error("action_sequence() is not implemented by testdriver-vendor.js");
+        },
+
+        async generate_test_report(message, context=null) {
+            throw new Error("generate_test_report() is not implemented by testdriver-vendor.js");
+        },
+
+        async set_permission(permission_params, context=null) {
+            throw new Error("set_permission() is not implemented by testdriver-vendor.js");
+        },
+
+        async add_virtual_authenticator(config, context=null) {
+            throw new Error("add_virtual_authenticator() is not implemented by testdriver-vendor.js");
+        },
+
+        async remove_virtual_authenticator(authenticator_id, context=null) {
+            throw new Error("remove_virtual_authenticator() is not implemented by testdriver-vendor.js");
+        },
+
+        async add_credential(authenticator_id, credential, context=null) {
+            throw new Error("add_credential() is not implemented by testdriver-vendor.js");
+        },
+
+        async get_credentials(authenticator_id, context=null) {
+            throw new Error("get_credentials() is not implemented by testdriver-vendor.js");
+        },
+
+        async remove_credential(authenticator_id, credential_id, context=null) {
+            throw new Error("remove_credential() is not implemented by testdriver-vendor.js");
+        },
+
+        async remove_all_credentials(authenticator_id, context=null) {
+            throw new Error("remove_all_credentials() is not implemented by testdriver-vendor.js");
+        },
+
+        async set_user_verified(authenticator_id, uv, context=null) {
+            throw new Error("set_user_verified() is not implemented by testdriver-vendor.js");
+        },
+
+        async set_storage_access(origin, embedding_origin, blocked, context=null) {
+            throw new Error("set_storage_access() is not implemented by testdriver-vendor.js");
+        },
+
+        async set_spc_transaction_mode(mode, context=null) {
+            throw new Error("set_spc_transaction_mode() is not implemented by testdriver-vendor.js");
+        },
+
+        async cancel_fedcm_dialog(context=null) {
+            throw new Error("cancel_fedcm_dialog() is not implemented by testdriver-vendor.js");
+        },
+
+        async select_fedcm_account(account_index, context=null) {
+            throw new Error("select_fedcm_account() is not implemented by testdriver-vendor.js");
+        },
+
+        async get_fedcm_account_list(context=null) {
+            throw new Error("get_fedcm_account_list() is not implemented by testdriver-vendor.js");
+        },
+
+        async get_fedcm_dialog_title(context=null) {
+            throw new Error("get_fedcm_dialog_title() is not implemented by testdriver-vendor.js");
+        },
+
+        async get_fedcm_dialog_type(context=null) {
+            throw new Error("get_fedcm_dialog_type() is not implemented by testdriver-vendor.js");
+        },
+
+        async set_fedcm_delay_enabled(enabled, context=null) {
+            throw new Error("set_fedcm_delay_enabled() is not implemented by testdriver-vendor.js");
+        },
+
+        async reset_fedcm_cooldown(context=null) {
+            throw new Error("reset_fedcm_cooldown() is not implemented by testdriver-vendor.js");
+        }
+    };
+})();
diff --git a/test/wpt/tests/resources/testdriver.js.headers b/test/wpt/tests/resources/testdriver.js.headers
new file mode 100644
index 0000000..5e8f640
--- /dev/null
+++ b/test/wpt/tests/resources/testdriver.js.headers
@@ -0,0 +1,2 @@
+Content-Type: text/javascript; charset=utf-8
+Cache-Control: max-age=3600
diff --git a/test/wpt/tests/resources/testharness.js b/test/wpt/tests/resources/testharness.js
new file mode 100644
index 0000000..4139930
--- /dev/null
+++ b/test/wpt/tests/resources/testharness.js
@@ -0,0 +1,4933 @@
+/*global self*/
+/*jshint latedef: nofunc*/
+
+/* Documentation: https://web-platform-tests.org/writing-tests/testharness-api.html
+ * (../docs/_writing-tests/testharness-api.md) */
+
+(function (global_scope)
+{
+    // default timeout is 10 seconds, test can override if needed
+    var settings = {
+        output:true,
+        harness_timeout:{
+            "normal":10000,
+            "long":60000
+        },
+        test_timeout:null,
+        message_events: ["start", "test_state", "result", "completion"],
+        debug: false,
+    };
+
+    var xhtml_ns = "http://www.w3.org/1999/xhtml";
+
+    /*
+     * TestEnvironment is an abstraction for the environment in which the test
+     * harness is used. Each implementation of a test environment has to provide
+     * the following interface:
+     *
+     * interface TestEnvironment {
+     *   // Invoked after the global 'tests' object has been created and it's
+     *   // safe to call add_*_callback() to register event handlers.
+     *   void on_tests_ready();
+     *
+     *   // Invoked after setup() has been called to notify the test environment
+     *   // of changes to the test harness properties.
+     *   void on_new_harness_properties(object properties);
+     *
+     *   // Should return a new unique default test name.
+     *   DOMString next_default_test_name();
+     *
+     *   // Should return the test harness timeout duration in milliseconds.
+     *   float test_timeout();
+     * };
+     */
+
+    /*
+     * A test environment with a DOM. The global object is 'window'. By default
+     * test results are displayed in a table. Any parent windows receive
+     * callbacks or messages via postMessage() when test events occur. See
+     * apisample11.html and apisample12.html.
+     */
+    function WindowTestEnvironment() {
+        this.name_counter = 0;
+        this.window_cache = null;
+        this.output_handler = null;
+        this.all_loaded = false;
+        var this_obj = this;
+        this.message_events = [];
+        this.dispatched_messages = [];
+
+        this.message_functions = {
+            start: [add_start_callback, remove_start_callback,
+                    function (properties) {
+                        this_obj._dispatch("start_callback", [properties],
+                                           {type: "start", properties: properties});
+                    }],
+
+            test_state: [add_test_state_callback, remove_test_state_callback,
+                         function(test) {
+                             this_obj._dispatch("test_state_callback", [test],
+                                                {type: "test_state",
+                                                 test: test.structured_clone()});
+                         }],
+            result: [add_result_callback, remove_result_callback,
+                     function (test) {
+                         this_obj.output_handler.show_status();
+                         this_obj._dispatch("result_callback", [test],
+                                            {type: "result",
+                                             test: test.structured_clone()});
+                     }],
+            completion: [add_completion_callback, remove_completion_callback,
+                         function (tests, harness_status, asserts) {
+                             var cloned_tests = map(tests, function(test) {
+                                 return test.structured_clone();
+                             });
+                             this_obj._dispatch("completion_callback", [tests, harness_status],
+                                                {type: "complete",
+                                                 tests: cloned_tests,
+                                                 status: harness_status.structured_clone(),
+                                                 asserts: asserts.map(assert => assert.structured_clone())});
+                         }]
+        }
+
+        on_event(window, 'load', function() {
+            this_obj.all_loaded = true;
+        });
+
+        on_event(window, 'message', function(event) {
+            if (event.data && event.data.type === "getmessages" && event.source) {
+                // A window can post "getmessages" to receive a duplicate of every
+                // message posted by this environment so far. This allows subscribers
+                // from fetch_tests_from_window to 'catch up' to the current state of
+                // this environment.
+                for (var i = 0; i < this_obj.dispatched_messages.length; ++i)
+                {
+                    event.source.postMessage(this_obj.dispatched_messages[i], "*");
+                }
+            }
+        });
+    }
+
+    WindowTestEnvironment.prototype._dispatch = function(selector, callback_args, message_arg) {
+        this.dispatched_messages.push(message_arg);
+        this._forEach_windows(
+                function(w, same_origin) {
+                    if (same_origin) {
+                        try {
+                            var has_selector = selector in w;
+                        } catch(e) {
+                            // If document.domain was set at some point same_origin can be
+                            // wrong and the above will fail.
+                            has_selector = false;
+                        }
+                        if (has_selector) {
+                            try {
+                                w[selector].apply(undefined, callback_args);
+                            } catch (e) {}
+                        }
+                    }
+                    if (w !== self) {
+                        w.postMessage(message_arg, "*");
+                    }
+                });
+    };
+
+    WindowTestEnvironment.prototype._forEach_windows = function(callback) {
+        // Iterate over the windows [self ... top, opener]. The callback is passed
+        // two objects, the first one is the window object itself, the second one
+        // is a boolean indicating whether or not it's on the same origin as the
+        // current window.
+        var cache = this.window_cache;
+        if (!cache) {
+            cache = [[self, true]];
+            var w = self;
+            var i = 0;
+            var so;
+            while (w != w.parent) {
+                w = w.parent;
+                so = is_same_origin(w);
+                cache.push([w, so]);
+                i++;
+            }
+            w = window.opener;
+            if (w) {
+                cache.push([w, is_same_origin(w)]);
+            }
+            this.window_cache = cache;
+        }
+
+        forEach(cache,
+                function(a) {
+                    callback.apply(null, a);
+                });
+    };
+
+    WindowTestEnvironment.prototype.on_tests_ready = function() {
+        var output = new Output();
+        this.output_handler = output;
+
+        var this_obj = this;
+
+        add_start_callback(function (properties) {
+            this_obj.output_handler.init(properties);
+        });
+
+        add_test_state_callback(function(test) {
+            this_obj.output_handler.show_status();
+        });
+
+        add_result_callback(function (test) {
+            this_obj.output_handler.show_status();
+        });
+
+        add_completion_callback(function (tests, harness_status, asserts_run) {
+            this_obj.output_handler.show_results(tests, harness_status, asserts_run);
+        });
+        this.setup_messages(settings.message_events);
+    };
+
+    WindowTestEnvironment.prototype.setup_messages = function(new_events) {
+        var this_obj = this;
+        forEach(settings.message_events, function(x) {
+            var current_dispatch = this_obj.message_events.indexOf(x) !== -1;
+            var new_dispatch = new_events.indexOf(x) !== -1;
+            if (!current_dispatch && new_dispatch) {
+                this_obj.message_functions[x][0](this_obj.message_functions[x][2]);
+            } else if (current_dispatch && !new_dispatch) {
+                this_obj.message_functions[x][1](this_obj.message_functions[x][2]);
+            }
+        });
+        this.message_events = new_events;
+    }
+
+    WindowTestEnvironment.prototype.next_default_test_name = function() {
+        var suffix = this.name_counter > 0 ? " " + this.name_counter : "";
+        this.name_counter++;
+        return get_title() + suffix;
+    };
+
+    WindowTestEnvironment.prototype.on_new_harness_properties = function(properties) {
+        this.output_handler.setup(properties);
+        if (properties.hasOwnProperty("message_events")) {
+            this.setup_messages(properties.message_events);
+        }
+    };
+
+    WindowTestEnvironment.prototype.add_on_loaded_callback = function(callback) {
+        on_event(window, 'load', callback);
+    };
+
+    WindowTestEnvironment.prototype.test_timeout = function() {
+        var metas = document.getElementsByTagName("meta");
+        for (var i = 0; i < metas.length; i++) {
+            if (metas[i].name == "timeout") {
+                if (metas[i].content == "long") {
+                    return settings.harness_timeout.long;
+                }
+                break;
+            }
+        }
+        return settings.harness_timeout.normal;
+    };
+
+    /*
+     * Base TestEnvironment implementation for a generic web worker.
+     *
+     * Workers accumulate test results. One or more clients can connect and
+     * retrieve results from a worker at any time.
+     *
+     * WorkerTestEnvironment supports communicating with a client via a
+     * MessagePort.  The mechanism for determining the appropriate MessagePort
+     * for communicating with a client depends on the type of worker and is
+     * implemented by the various specializations of WorkerTestEnvironment
+     * below.
+     *
+     * A client document using testharness can use fetch_tests_from_worker() to
+     * retrieve results from a worker. See apisample16.html.
+     */
+    function WorkerTestEnvironment() {
+        this.name_counter = 0;
+        this.all_loaded = true;
+        this.message_list = [];
+        this.message_ports = [];
+    }
+
+    WorkerTestEnvironment.prototype._dispatch = function(message) {
+        this.message_list.push(message);
+        for (var i = 0; i < this.message_ports.length; ++i)
+        {
+            this.message_ports[i].postMessage(message);
+        }
+    };
+
+    // The only requirement is that port has a postMessage() method. It doesn't
+    // have to be an instance of a MessagePort, and often isn't.
+    WorkerTestEnvironment.prototype._add_message_port = function(port) {
+        this.message_ports.push(port);
+        for (var i = 0; i < this.message_list.length; ++i)
+        {
+            port.postMessage(this.message_list[i]);
+        }
+    };
+
+    WorkerTestEnvironment.prototype.next_default_test_name = function() {
+        var suffix = this.name_counter > 0 ? " " + this.name_counter : "";
+        this.name_counter++;
+        return get_title() + suffix;
+    };
+
+    WorkerTestEnvironment.prototype.on_new_harness_properties = function() {};
+
+    WorkerTestEnvironment.prototype.on_tests_ready = function() {
+        var this_obj = this;
+        add_start_callback(
+                function(properties) {
+                    this_obj._dispatch({
+                        type: "start",
+                        properties: properties,
+                    });
+                });
+        add_test_state_callback(
+                function(test) {
+                    this_obj._dispatch({
+                        type: "test_state",
+                        test: test.structured_clone()
+                    });
+                });
+        add_result_callback(
+                function(test) {
+                    this_obj._dispatch({
+                        type: "result",
+                        test: test.structured_clone()
+                    });
+                });
+        add_completion_callback(
+                function(tests, harness_status, asserts) {
+                    this_obj._dispatch({
+                        type: "complete",
+                        tests: map(tests,
+                            function(test) {
+                                return test.structured_clone();
+                            }),
+                        status: harness_status.structured_clone(),
+                        asserts: asserts.map(assert => assert.structured_clone()),
+                    });
+                });
+    };
+
+    WorkerTestEnvironment.prototype.add_on_loaded_callback = function() {};
+
+    WorkerTestEnvironment.prototype.test_timeout = function() {
+        // Tests running in a worker don't have a default timeout. I.e. all
+        // worker tests behave as if settings.explicit_timeout is true.
+        return null;
+    };
+
+    /*
+     * Dedicated web workers.
+     * https://html.spec.whatwg.org/multipage/workers.html#dedicatedworkerglobalscope
+     *
+     * This class is used as the test_environment when testharness is running
+     * inside a dedicated worker.
+     */
+    function DedicatedWorkerTestEnvironment() {
+        WorkerTestEnvironment.call(this);
+        // self is an instance of DedicatedWorkerGlobalScope which exposes
+        // a postMessage() method for communicating via the message channel
+        // established when the worker is created.
+        this._add_message_port(self);
+    }
+    DedicatedWorkerTestEnvironment.prototype = Object.create(WorkerTestEnvironment.prototype);
+
+    DedicatedWorkerTestEnvironment.prototype.on_tests_ready = function() {
+        WorkerTestEnvironment.prototype.on_tests_ready.call(this);
+        // In the absence of an onload notification, we a require dedicated
+        // workers to explicitly signal when the tests are done.
+        tests.wait_for_finish = true;
+    };
+
+    /*
+     * Shared web workers.
+     * https://html.spec.whatwg.org/multipage/workers.html#sharedworkerglobalscope
+     *
+     * This class is used as the test_environment when testharness is running
+     * inside a shared web worker.
+     */
+    function SharedWorkerTestEnvironment() {
+        WorkerTestEnvironment.call(this);
+        var this_obj = this;
+        // Shared workers receive message ports via the 'onconnect' event for
+        // each connection.
+        self.addEventListener("connect",
+                function(message_event) {
+                    this_obj._add_message_port(message_event.source);
+                }, false);
+    }
+    SharedWorkerTestEnvironment.prototype = Object.create(WorkerTestEnvironment.prototype);
+
+    SharedWorkerTestEnvironment.prototype.on_tests_ready = function() {
+        WorkerTestEnvironment.prototype.on_tests_ready.call(this);
+        // In the absence of an onload notification, we a require shared
+        // workers to explicitly signal when the tests are done.
+        tests.wait_for_finish = true;
+    };
+
+    /*
+     * Service workers.
+     * http://www.w3.org/TR/service-workers/
+     *
+     * This class is used as the test_environment when testharness is running
+     * inside a service worker.
+     */
+    function ServiceWorkerTestEnvironment() {
+        WorkerTestEnvironment.call(this);
+        this.all_loaded = false;
+        this.on_loaded_callback = null;
+        var this_obj = this;
+        self.addEventListener("message",
+                function(event) {
+                    if (event.data && event.data.type && event.data.type === "connect") {
+                        this_obj._add_message_port(event.source);
+                    }
+                }, false);
+
+        // The oninstall event is received after the service worker script and
+        // all imported scripts have been fetched and executed. It's the
+        // equivalent of an onload event for a document. All tests should have
+        // been added by the time this event is received, thus it's not
+        // necessary to wait until the onactivate event. However, tests for
+        // installed service workers need another event which is equivalent to
+        // the onload event because oninstall is fired only on installation. The
+        // onmessage event is used for that purpose since tests using
+        // testharness.js should ask the result to its service worker by
+        // PostMessage. If the onmessage event is triggered on the service
+        // worker's context, that means the worker's script has been evaluated.
+        on_event(self, "install", on_all_loaded);
+        on_event(self, "message", on_all_loaded);
+        function on_all_loaded() {
+            if (this_obj.all_loaded)
+                return;
+            this_obj.all_loaded = true;
+            if (this_obj.on_loaded_callback) {
+              this_obj.on_loaded_callback();
+            }
+        }
+    }
+
+    ServiceWorkerTestEnvironment.prototype = Object.create(WorkerTestEnvironment.prototype);
+
+    ServiceWorkerTestEnvironment.prototype.add_on_loaded_callback = function(callback) {
+        if (this.all_loaded) {
+            callback();
+        } else {
+            this.on_loaded_callback = callback;
+        }
+    };
+
+    /*
+     * Shadow realms.
+     * https://github.com/tc39/proposal-shadowrealm
+     *
+     * This class is used as the test_environment when testharness is running
+     * inside a shadow realm.
+     */
+    function ShadowRealmTestEnvironment() {
+        WorkerTestEnvironment.call(this);
+        this.all_loaded = false;
+        this.on_loaded_callback = null;
+    }
+
+    ShadowRealmTestEnvironment.prototype = Object.create(WorkerTestEnvironment.prototype);
+
+    /**
+     * Signal to the test environment that the tests are ready and the on-loaded
+     * callback should be run.
+     *
+     * Shadow realms are not *really* a DOM context: they have no `onload` or similar
+     * event for us to use to set up the test environment; so, instead, this method
+     * is manually triggered from the incubating realm
+     *
+     * @param {Function} message_destination - a function that receives JSON-serializable
+     * data to send to the incubating realm, in the same format as used by RemoteContext
+     */
+    ShadowRealmTestEnvironment.prototype.begin = function(message_destination) {
+        if (this.all_loaded) {
+            throw new Error("Tried to start a shadow realm test environment after it has already started");
+        }
+        var fakeMessagePort = {};
+        fakeMessagePort.postMessage = message_destination;
+        this._add_message_port(fakeMessagePort);
+        this.all_loaded = true;
+        if (this.on_loaded_callback) {
+            this.on_loaded_callback();
+        }
+    };
+
+    ShadowRealmTestEnvironment.prototype.add_on_loaded_callback = function(callback) {
+        if (this.all_loaded) {
+            callback();
+        } else {
+            this.on_loaded_callback = callback;
+        }
+    };
+
+    /*
+     * JavaScript shells.
+     *
+     * This class is used as the test_environment when testharness is running
+     * inside a JavaScript shell.
+     */
+    function ShellTestEnvironment() {
+        this.name_counter = 0;
+        this.all_loaded = false;
+        this.on_loaded_callback = null;
+        Promise.resolve().then(function() {
+            this.all_loaded = true
+            if (this.on_loaded_callback) {
+                this.on_loaded_callback();
+            }
+        }.bind(this));
+        this.message_list = [];
+        this.message_ports = [];
+    }
+
+    ShellTestEnvironment.prototype.next_default_test_name = function() {
+        var suffix = this.name_counter > 0 ? " " + this.name_counter : "";
+        this.name_counter++;
+        return get_title() + suffix;
+    };
+
+    ShellTestEnvironment.prototype.on_new_harness_properties = function() {};
+
+    ShellTestEnvironment.prototype.on_tests_ready = function() {};
+
+    ShellTestEnvironment.prototype.add_on_loaded_callback = function(callback) {
+        if (this.all_loaded) {
+            callback();
+        } else {
+            this.on_loaded_callback = callback;
+        }
+    };
+
+    ShellTestEnvironment.prototype.test_timeout = function() {
+        // Tests running in a shell don't have a default timeout, so behave as
+        // if settings.explicit_timeout is true.
+        return null;
+    };
+
+    function create_test_environment() {
+        if ('document' in global_scope) {
+            return new WindowTestEnvironment();
+        }
+        if ('DedicatedWorkerGlobalScope' in global_scope &&
+            global_scope instanceof DedicatedWorkerGlobalScope) {
+            return new DedicatedWorkerTestEnvironment();
+        }
+        if ('SharedWorkerGlobalScope' in global_scope &&
+            global_scope instanceof SharedWorkerGlobalScope) {
+            return new SharedWorkerTestEnvironment();
+        }
+        if ('ServiceWorkerGlobalScope' in global_scope &&
+            global_scope instanceof ServiceWorkerGlobalScope) {
+            return new ServiceWorkerTestEnvironment();
+        }
+        if ('WorkerGlobalScope' in global_scope &&
+            global_scope instanceof WorkerGlobalScope) {
+            return new DedicatedWorkerTestEnvironment();
+        }
+        /* Shadow realm global objects are _ordinary_ objects (i.e. their prototype is
+         * Object) so we don't have a nice `instanceof` test to use; instead, we
+         * check if the there is a GLOBAL.isShadowRealm() property
+         * on the global object. that was set by the test harness when it
+         * created the ShadowRealm.
+         */
+        if (global_scope.GLOBAL && global_scope.GLOBAL.isShadowRealm()) {
+            return new ShadowRealmTestEnvironment();
+        }
+
+        return new ShellTestEnvironment();
+    }
+
+    var test_environment = create_test_environment();
+
+    function is_shared_worker(worker) {
+        return 'SharedWorker' in global_scope && worker instanceof SharedWorker;
+    }
+
+    function is_service_worker(worker) {
+        // The worker object may be from another execution context,
+        // so do not use instanceof here.
+        return 'ServiceWorker' in global_scope &&
+            Object.prototype.toString.call(worker) == '[object ServiceWorker]';
+    }
+
+    var seen_func_name = Object.create(null);
+
+    function get_test_name(func, name)
+    {
+        if (name) {
+            return name;
+        }
+
+        if (func) {
+            var func_code = func.toString();
+
+            // Try and match with brackets, but fallback to matching without
+            var arrow = func_code.match(/^\(\)\s*=>\s*(?:{(.*)}\s*|(.*))$/);
+
+            // Check for JS line separators
+            if (arrow !== null && !/[\u000A\u000D\u2028\u2029]/.test(func_code)) {
+                var trimmed = (arrow[1] !== undefined ? arrow[1] : arrow[2]).trim();
+                // drop trailing ; if there's no earlier ones
+                trimmed = trimmed.replace(/^([^;]*)(;\s*)+$/, "$1");
+
+                if (trimmed) {
+                    let name = trimmed;
+                    if (seen_func_name[trimmed]) {
+                        // This subtest name already exists, so add a suffix.
+                        name += " " + seen_func_name[trimmed];
+                    } else {
+                        seen_func_name[trimmed] = 0;
+                    }
+                    seen_func_name[trimmed] += 1;
+                    return name;
+                }
+            }
+        }
+
+        return test_environment.next_default_test_name();
+    }
+
+    /**
+     * @callback TestFunction
+     * @param {Test} test - The test currnetly being run.
+     * @param {Any[]} args - Additional args to pass to function.
+     *
+     */
+
+    /**
+     * Create a synchronous test
+     *
+     * @param {TestFunction} func - Test function. This is executed
+     * immediately. If it returns without error, the test status is
+     * set to ``PASS``. If it throws an :js:class:`AssertionError`, or
+     * any other exception, the test status is set to ``FAIL``
+     * (typically from an `assert` function).
+     * @param {String} name - Test name. This must be unique in a
+     * given file and must be invariant between runs.
+     */
+    function test(func, name, properties)
+    {
+        if (tests.promise_setup_called) {
+            tests.status.status = tests.status.ERROR;
+            tests.status.message = '`test` invoked after `promise_setup`';
+            tests.complete();
+        }
+        var test_name = get_test_name(func, name);
+        var test_obj = new Test(test_name, properties);
+        var value = test_obj.step(func, test_obj, test_obj);
+
+        if (value !== undefined) {
+            var msg = 'Test named "' + test_name +
+                '" passed a function to `test` that returned a value.';
+
+            try {
+                if (value && typeof value.then === 'function') {
+                    msg += ' Consider using `promise_test` instead when ' +
+                        'using Promises or async/await.';
+                }
+            } catch (err) {}
+
+            tests.status.status = tests.status.ERROR;
+            tests.status.message = msg;
+        }
+
+        if (test_obj.phase === test_obj.phases.STARTED) {
+            test_obj.done();
+        }
+    }
+
+    /**
+     * Create an asynchronous test
+     *
+     * @param {TestFunction|string} funcOrName - Initial step function
+     * to call immediately with the test name as an argument (if any),
+     * or name of the test.
+     * @param {String} name - Test name (if a test function was
+     * provided). This must be unique in a given file and must be
+     * invariant between runs.
+     * @returns {Test} An object representing the ongoing test.
+     */
+    function async_test(func, name, properties)
+    {
+        if (tests.promise_setup_called) {
+            tests.status.status = tests.status.ERROR;
+            tests.status.message = '`async_test` invoked after `promise_setup`';
+            tests.complete();
+        }
+        if (typeof func !== "function") {
+            properties = name;
+            name = func;
+            func = null;
+        }
+        var test_name = get_test_name(func, name);
+        var test_obj = new Test(test_name, properties);
+        if (func) {
+            var value = test_obj.step(func, test_obj, test_obj);
+
+            // Test authors sometimes return values to async_test, expecting us
+            // to handle the value somehow. Make doing so a harness error to be
+            // clear this is invalid, and point authors to promise_test if it
+            // may be appropriate.
+            //
+            // Note that we only perform this check on the initial function
+            // passed to async_test, not on any later steps - we haven't seen a
+            // consistent problem with those (and it's harder to check).
+            if (value !== undefined) {
+                var msg = 'Test named "' + test_name +
+                    '" passed a function to `async_test` that returned a value.';
+
+                try {
+                    if (value && typeof value.then === 'function') {
+                        msg += ' Consider using `promise_test` instead when ' +
+                            'using Promises or async/await.';
+                    }
+                } catch (err) {}
+
+                tests.set_status(tests.status.ERROR, msg);
+                tests.complete();
+            }
+        }
+        return test_obj;
+    }
+
+    /**
+     * Create a promise test.
+     *
+     * Promise tests are tests which are represented by a promise
+     * object. If the promise is fulfilled the test passes, if it's
+     * rejected the test fails, otherwise the test passes.
+     *
+     * @param {TestFunction} func - Test function. This must return a
+     * promise. The test is automatically marked as complete once the
+     * promise settles.
+     * @param {String} name - Test name. This must be unique in a
+     * given file and must be invariant between runs.
+     */
+    function promise_test(func, name, properties) {
+        if (typeof func !== "function") {
+            properties = name;
+            name = func;
+            func = null;
+        }
+        var test_name = get_test_name(func, name);
+        var test = new Test(test_name, properties);
+        test._is_promise_test = true;
+
+        // If there is no promise tests queue make one.
+        if (!tests.promise_tests) {
+            tests.promise_tests = Promise.resolve();
+        }
+        tests.promise_tests = tests.promise_tests.then(function() {
+            return new Promise(function(resolve) {
+                var promise = test.step(func, test, test);
+
+                test.step(function() {
+                    assert(!!promise, "promise_test", null,
+                           "test body must return a 'thenable' object (received ${value})",
+                           {value:promise});
+                    assert(typeof promise.then === "function", "promise_test", null,
+                           "test body must return a 'thenable' object (received an object with no `then` method)",
+                           null);
+                });
+
+                // Test authors may use the `step` method within a
+                // `promise_test` even though this reflects a mixture of
+                // asynchronous control flow paradigms. The "done" callback
+                // should be registered prior to the resolution of the
+                // user-provided Promise to avoid timeouts in cases where the
+                // Promise does not settle but a `step` function has thrown an
+                // error.
+                add_test_done_callback(test, resolve);
+
+                Promise.resolve(promise)
+                    .catch(test.step_func(
+                        function(value) {
+                            if (value instanceof AssertionError) {
+                                throw value;
+                            }
+                            assert(false, "promise_test", null,
+                                   "Unhandled rejection with value: ${value}", {value:value});
+                        }))
+                    .then(function() {
+                        test.done();
+                    });
+                });
+        });
+    }
+
+    /**
+     * Make a copy of a Promise in the current realm.
+     *
+     * @param {Promise} promise the given promise that may be from a different
+     *                          realm
+     * @returns {Promise}
+     *
+     * An arbitrary promise provided by the caller may have originated
+     * in another frame that have since navigated away, rendering the
+     * frame's document inactive. Such a promise cannot be used with
+     * `await` or Promise.resolve(), as microtasks associated with it
+     * may be prevented from being run. See `issue
+     * 5319<https://github.com/whatwg/html/issues/5319>`_ for a
+     * particular case.
+     *
+     * In functions we define here, there is an expectation from the caller
+     * that the promise is from the current realm, that can always be used with
+     * `await`, etc. We therefore create a new promise in this realm that
+     * inherit the value and status from the given promise.
+     */
+
+    function bring_promise_to_current_realm(promise) {
+        return new Promise(promise.then.bind(promise));
+    }
+
+    /**
+     * Assert that a Promise is rejected with the right ECMAScript exception.
+     *
+     * @param {Test} test - the `Test` to use for the assertion.
+     * @param {Function} constructor - The expected exception constructor.
+     * @param {Promise} promise - The promise that's expected to
+     * reject with the given exception.
+     * @param {string} [description] Error message to add to assert in case of
+     *                               failure.
+     */
+    function promise_rejects_js(test, constructor, promise, description) {
+        return bring_promise_to_current_realm(promise)
+            .then(test.unreached_func("Should have rejected: " + description))
+            .catch(function(e) {
+                assert_throws_js_impl(constructor, function() { throw e },
+                                      description, "promise_rejects_js");
+            });
+    }
+
+    /**
+     * Assert that a Promise is rejected with the right DOMException.
+     *
+     * For the remaining arguments, there are two ways of calling
+     * promise_rejects_dom:
+     *
+     * 1) If the DOMException is expected to come from the current global, the
+     * third argument should be the promise expected to reject, and a fourth,
+     * optional, argument is the assertion description.
+     *
+     * 2) If the DOMException is expected to come from some other global, the
+     * third argument should be the DOMException constructor from that global,
+     * the fourth argument the promise expected to reject, and the fifth,
+     * optional, argument the assertion description.
+     *
+     * @param {Test} test - the `Test` to use for the assertion.
+     * @param {number|string} type - See documentation for
+     * `assert_throws_dom <#assert_throws_dom>`_.
+     * @param {Function} promiseOrConstructor - Either the constructor
+     * for the expected exception (if the exception comes from another
+     * global), or the promise that's expected to reject (if the
+     * exception comes from the current global).
+     * @param {Function|string} descriptionOrPromise - Either the
+     * promise that's expected to reject (if the exception comes from
+     * another global), or the optional description of the condition
+     * being tested (if the exception comes from the current global).
+     * @param {string} [description] - Description of the condition
+     * being tested (if the exception comes from another global).
+     *
+     */
+    function promise_rejects_dom(test, type, promiseOrConstructor, descriptionOrPromise, maybeDescription) {
+        let constructor, promise, description;
+        if (typeof promiseOrConstructor === "function" &&
+            promiseOrConstructor.name === "DOMException") {
+            constructor = promiseOrConstructor;
+            promise = descriptionOrPromise;
+            description = maybeDescription;
+        } else {
+            constructor = self.DOMException;
+            promise = promiseOrConstructor;
+            description = descriptionOrPromise;
+            assert(maybeDescription === undefined,
+                   "Too many args pased to no-constructor version of promise_rejects_dom");
+        }
+        return bring_promise_to_current_realm(promise)
+            .then(test.unreached_func("Should have rejected: " + description))
+            .catch(function(e) {
+                assert_throws_dom_impl(type, function() { throw e }, description,
+                                       "promise_rejects_dom", constructor);
+            });
+    }
+
+    /**
+     * Assert that a Promise is rejected with the provided value.
+     *
+     * @param {Test} test - the `Test` to use for the assertion.
+     * @param {Any} exception - The expected value of the rejected promise.
+     * @param {Promise} promise - The promise that's expected to
+     * reject.
+     * @param {string} [description] Error message to add to assert in case of
+     *                               failure.
+     */
+    function promise_rejects_exactly(test, exception, promise, description) {
+        return bring_promise_to_current_realm(promise)
+            .then(test.unreached_func("Should have rejected: " + description))
+            .catch(function(e) {
+                assert_throws_exactly_impl(exception, function() { throw e },
+                                           description, "promise_rejects_exactly");
+            });
+    }
+
+    /**
+     * Allow DOM events to be handled using Promises.
+     *
+     * This can make it a lot easier to test a very specific series of events,
+     * including ensuring that unexpected events are not fired at any point.
+     *
+     * `EventWatcher` will assert if an event occurs while there is no `wait_for`
+     * created Promise waiting to be fulfilled, or if the event is of a different type
+     * to the type currently expected. This ensures that only the events that are
+     * expected occur, in the correct order, and with the correct timing.
+     *
+     * @constructor
+     * @param {Test} test - The `Test` to use for the assertion.
+     * @param {EventTarget} watchedNode - The target expected to receive the events.
+     * @param {string[]} eventTypes - List of events to watch for.
+     * @param {Promise} timeoutPromise - Promise that will cause the
+     * test to be set to `TIMEOUT` once fulfilled.
+     *
+     */
+    function EventWatcher(test, watchedNode, eventTypes, timeoutPromise)
+    {
+        if (typeof eventTypes == 'string') {
+            eventTypes = [eventTypes];
+        }
+
+        var waitingFor = null;
+
+        // This is null unless we are recording all events, in which case it
+        // will be an Array object.
+        var recordedEvents = null;
+
+        var eventHandler = test.step_func(function(evt) {
+            assert_true(!!waitingFor,
+                        'Not expecting event, but got ' + evt.type + ' event');
+            assert_equals(evt.type, waitingFor.types[0],
+                          'Expected ' + waitingFor.types[0] + ' event, but got ' +
+                          evt.type + ' event instead');
+
+            if (Array.isArray(recordedEvents)) {
+                recordedEvents.push(evt);
+            }
+
+            if (waitingFor.types.length > 1) {
+                // Pop first event from array
+                waitingFor.types.shift();
+                return;
+            }
+            // We need to null out waitingFor before calling the resolve function
+            // since the Promise's resolve handlers may call wait_for() which will
+            // need to set waitingFor.
+            var resolveFunc = waitingFor.resolve;
+            waitingFor = null;
+            // Likewise, we should reset the state of recordedEvents.
+            var result = recordedEvents || evt;
+            recordedEvents = null;
+            resolveFunc(result);
+        });
+
+        for (var i = 0; i < eventTypes.length; i++) {
+            watchedNode.addEventListener(eventTypes[i], eventHandler, false);
+        }
+
+        /**
+         * Returns a Promise that will resolve after the specified event or
+         * series of events has occurred.
+         *
+         * @param {Object} options An optional options object. If the 'record' property
+         *                 on this object has the value 'all', when the Promise
+         *                 returned by this function is resolved,  *all* Event
+         *                 objects that were waited for will be returned as an
+         *                 array.
+         *
+         * @example
+         * const watcher = new EventWatcher(t, div, [ 'animationstart',
+         *                                            'animationiteration',
+         *                                            'animationend' ]);
+         * return watcher.wait_for([ 'animationstart', 'animationend' ],
+         *                         { record: 'all' }).then(evts => {
+         *   assert_equals(evts[0].elapsedTime, 0.0);
+         *   assert_equals(evts[1].elapsedTime, 2.0);
+         * });
+         */
+        this.wait_for = function(types, options) {
+            if (waitingFor) {
+                return Promise.reject('Already waiting for an event or events');
+            }
+            if (typeof types == 'string') {
+                types = [types];
+            }
+            if (options && options.record && options.record === 'all') {
+                recordedEvents = [];
+            }
+            return new Promise(function(resolve, reject) {
+                var timeout = test.step_func(function() {
+                    // If the timeout fires after the events have been received
+                    // or during a subsequent call to wait_for, ignore it.
+                    if (!waitingFor || waitingFor.resolve !== resolve)
+                        return;
+
+                    // This should always fail, otherwise we should have
+                    // resolved the promise.
+                    assert_true(waitingFor.types.length == 0,
+                                'Timed out waiting for ' + waitingFor.types.join(', '));
+                    var result = recordedEvents;
+                    recordedEvents = null;
+                    var resolveFunc = waitingFor.resolve;
+                    waitingFor = null;
+                    resolveFunc(result);
+                });
+
+                if (timeoutPromise) {
+                    timeoutPromise().then(timeout);
+                }
+
+                waitingFor = {
+                    types: types,
+                    resolve: resolve,
+                    reject: reject
+                };
+            });
+        };
+
+        /**
+         * Stop listening for events
+         */
+        function stop_watching() {
+            for (var i = 0; i < eventTypes.length; i++) {
+                watchedNode.removeEventListener(eventTypes[i], eventHandler, false);
+            }
+        };
+
+        test._add_cleanup(stop_watching);
+
+        return this;
+    }
+    expose(EventWatcher, 'EventWatcher');
+
+    /**
+     * @typedef {Object} SettingsObject
+     * @property {bool} single_test - Use the single-page-test
+     * mode. In this mode the Document represents a single
+     * `async_test`. Asserts may be used directly without requiring
+     * `Test.step` or similar wrappers, and any exceptions set the
+     * status of the test rather than the status of the harness.
+     * @property {bool} allow_uncaught_exception - don't treat an
+     * uncaught exception as an error; needed when e.g. testing the
+     * `window.onerror` handler.
+     * @property {boolean} explicit_done - Wait for a call to `done()`
+     * before declaring all tests complete (this is always true for
+     * single-page tests).
+     * @property hide_test_state - hide the test state output while
+     * the test is running; This is helpful when the output of the test state
+     * may interfere the test results.
+     * @property {bool} explicit_timeout - disable file timeout; only
+     * stop waiting for results when the `timeout()` function is
+     * called This should typically only be set for manual tests, or
+     * by a test runner that providees its own timeout mechanism.
+     * @property {number} timeout_multiplier - Multiplier to apply to
+     * per-test timeouts. This should only be set by a test runner.
+     * @property {Document} output_document - The document to which
+     * results should be logged. By default this is the current
+     * document but could be an ancestor document in some cases e.g. a
+     * SVG test loaded in an HTML wrapper
+     *
+     */
+
+    /**
+     * Configure the harness
+     *
+     * @param {Function|SettingsObject} funcOrProperties - Either a
+     * setup function to run, or a set of properties. If this is a
+     * function that function is run synchronously. Any exception in
+     * the function will set the overall harness status to `ERROR`.
+     * @param {SettingsObject} maybeProperties - An object containing
+     * the settings to use, if the first argument is a function.
+     *
+     */
+    function setup(func_or_properties, maybe_properties)
+    {
+        var func = null;
+        var properties = {};
+        if (arguments.length === 2) {
+            func = func_or_properties;
+            properties = maybe_properties;
+        } else if (func_or_properties instanceof Function) {
+            func = func_or_properties;
+        } else {
+            properties = func_or_properties;
+        }
+        tests.setup(func, properties);
+        test_environment.on_new_harness_properties(properties);
+    }
+
+    /**
+     * Configure the harness, waiting for a promise to resolve
+     * before running any `promise_test` tests.
+     *
+     * @param {Function} func - Function returning a promise that's
+     * run synchronously. Promise tests are not run until after this
+     * function has resolved.
+     * @param {SettingsObject} [properties] - An object containing
+     * the harness settings to use.
+     *
+     */
+    function promise_setup(func, properties={})
+    {
+        if (typeof func !== "function") {
+            tests.set_status(tests.status.ERROR,
+                             "promise_test invoked without a function");
+            tests.complete();
+            return;
+        }
+        tests.promise_setup_called = true;
+
+        if (!tests.promise_tests) {
+            tests.promise_tests = Promise.resolve();
+        }
+
+        tests.promise_tests = tests.promise_tests
+            .then(function()
+                  {
+                      var result;
+
+                      tests.setup(null, properties);
+                      result = func();
+                      test_environment.on_new_harness_properties(properties);
+
+                      if (!result || typeof result.then !== "function") {
+                          throw "Non-thenable returned by function passed to `promise_setup`";
+                      }
+                      return result;
+                  })
+            .catch(function(e)
+                   {
+                       tests.set_status(tests.status.ERROR,
+                                        String(e),
+                                        e && e.stack);
+                       tests.complete();
+                   });
+    }
+
+    /**
+     * Mark test loading as complete.
+     *
+     * Typically this function is called implicitly on page load; it's
+     * only necessary for users to call this when either the
+     * ``explicit_done`` or ``single_page`` properties have been set
+     * via the :js:func:`setup` function.
+     *
+     * For single page tests this marks the test as complete and sets its status.
+     * For other tests, this marks test loading as complete, but doesn't affect ongoing tests.
+     */
+    function done() {
+        if (tests.tests.length === 0) {
+            // `done` is invoked after handling uncaught exceptions, so if the
+            // harness status is already set, the corresponding message is more
+            // descriptive than the generic message defined here.
+            if (tests.status.status === null) {
+                tests.status.status = tests.status.ERROR;
+                tests.status.message = "done() was called without first defining any tests";
+            }
+
+            tests.complete();
+            return;
+        }
+        if (tests.file_is_test) {
+            // file is test files never have asynchronous cleanup logic,
+            // meaning the fully-synchronous `done` function can be used here.
+            tests.tests[0].done();
+        }
+        tests.end_wait();
+    }
+
+    /**
+     * @deprecated generate a list of tests from a function and list of arguments
+     *
+     * This is deprecated because it runs all the tests outside of the test functions
+     * and as a result any test throwing an exception will result in no tests being
+     * run. In almost all cases, you should simply call test within the loop you would
+     * use to generate the parameter list array.
+     *
+     * @param {Function} func - The function that will be called for each generated tests.
+     * @param {Any[][]} args - An array of arrays. Each nested array
+     * has the structure `[testName, ...testArgs]`. For each of these nested arrays
+     * array, a test is generated with name `testName` and test function equivalent to
+     * `func(..testArgs)`.
+     */
+    function generate_tests(func, args, properties) {
+        forEach(args, function(x, i)
+                {
+                    var name = x[0];
+                    test(function()
+                         {
+                             func.apply(this, x.slice(1));
+                         },
+                         name,
+                         Array.isArray(properties) ? properties[i] : properties);
+                });
+    }
+
+    /**
+     * @deprecated
+     *
+     * Register a function as a DOM event listener to the
+     * given object for the event bubbling phase.
+     *
+     * @param {EventTarget} object - Event target
+     * @param {string} event - Event name
+     * @param {Function} callback - Event handler.
+     */
+    function on_event(object, event, callback)
+    {
+        object.addEventListener(event, callback, false);
+    }
+
+    /**
+     * Global version of :js:func:`Test.step_timeout` for use in single page tests.
+     *
+     * @param {Function} func - Function to run after the timeout
+     * @param {number} timeout - Time in ms to wait before running the
+     * test step. The actual wait time is ``timeout`` x
+     * ``timeout_multiplier``.
+     */
+    function step_timeout(func, timeout) {
+        var outer_this = this;
+        var args = Array.prototype.slice.call(arguments, 2);
+        return setTimeout(function() {
+            func.apply(outer_this, args);
+        }, timeout * tests.timeout_multiplier);
+    }
+
+    expose(test, 'test');
+    expose(async_test, 'async_test');
+    expose(promise_test, 'promise_test');
+    expose(promise_rejects_js, 'promise_rejects_js');
+    expose(promise_rejects_dom, 'promise_rejects_dom');
+    expose(promise_rejects_exactly, 'promise_rejects_exactly');
+    expose(generate_tests, 'generate_tests');
+    expose(setup, 'setup');
+    expose(promise_setup, 'promise_setup');
+    expose(done, 'done');
+    expose(on_event, 'on_event');
+    expose(step_timeout, 'step_timeout');
+
+    /*
+     * Return a string truncated to the given length, with ... added at the end
+     * if it was longer.
+     */
+    function truncate(s, len)
+    {
+        if (s.length > len) {
+            return s.substring(0, len - 3) + "...";
+        }
+        return s;
+    }
+
+    /*
+     * Return true if object is probably a Node object.
+     */
+    function is_node(object)
+    {
+        // I use duck-typing instead of instanceof, because
+        // instanceof doesn't work if the node is from another window (like an
+        // iframe's contentWindow):
+        // http://www.w3.org/Bugs/Public/show_bug.cgi?id=12295
+        try {
+            var has_node_properties = ("nodeType" in object &&
+                                       "nodeName" in object &&
+                                       "nodeValue" in object &&
+                                       "childNodes" in object);
+        } catch (e) {
+            // We're probably cross-origin, which means we aren't a node
+            return false;
+        }
+
+        if (has_node_properties) {
+            try {
+                object.nodeType;
+            } catch (e) {
+                // The object is probably Node.prototype or another prototype
+                // object that inherits from it, and not a Node instance.
+                return false;
+            }
+            return true;
+        }
+        return false;
+    }
+
+    var replacements = {
+        "0": "0",
+        "1": "x01",
+        "2": "x02",
+        "3": "x03",
+        "4": "x04",
+        "5": "x05",
+        "6": "x06",
+        "7": "x07",
+        "8": "b",
+        "9": "t",
+        "10": "n",
+        "11": "v",
+        "12": "f",
+        "13": "r",
+        "14": "x0e",
+        "15": "x0f",
+        "16": "x10",
+        "17": "x11",
+        "18": "x12",
+        "19": "x13",
+        "20": "x14",
+        "21": "x15",
+        "22": "x16",
+        "23": "x17",
+        "24": "x18",
+        "25": "x19",
+        "26": "x1a",
+        "27": "x1b",
+        "28": "x1c",
+        "29": "x1d",
+        "30": "x1e",
+        "31": "x1f",
+        "0xfffd": "ufffd",
+        "0xfffe": "ufffe",
+        "0xffff": "uffff",
+    };
+
+    /**
+     * Convert a value to a nice, human-readable string
+     *
+     * When many JavaScript Object values are coerced to a String, the
+     * resulting value will be ``"[object Object]"``. This obscures
+     * helpful information, making the coerced value unsuitable for
+     * use in assertion messages, test names, and debugging
+     * statements. `format_value` produces more distinctive string
+     * representations of many kinds of objects, including arrays and
+     * the more important DOM Node types. It also translates String
+     * values containing control characters to include human-readable
+     * representations.
+     *
+     * @example
+     * // "Document node with 2 children"
+     * format_value(document);
+     * @example
+     * // "\"foo\\uffffbar\""
+     * format_value("foo\uffffbar");
+     * @example
+     * // "[-0, Infinity]"
+     * format_value([-0, Infinity]);
+     * @param {Any} val - The value to convert to a string.
+     * @returns {string} - A string representation of ``val``, optimised for human readability.
+     */
+    function format_value(val, seen)
+    {
+        if (!seen) {
+            seen = [];
+        }
+        if (typeof val === "object" && val !== null) {
+            if (seen.indexOf(val) >= 0) {
+                return "[...]";
+            }
+            seen.push(val);
+        }
+        if (Array.isArray(val)) {
+            let output = "[";
+            if (val.beginEllipsis !== undefined) {
+                output += "…, ";
+            }
+            output += val.map(function(x) {return format_value(x, seen);}).join(", ");
+            if (val.endEllipsis !== undefined) {
+                output += ", …";
+            }
+            return output + "]";
+        }
+
+        switch (typeof val) {
+        case "string":
+            val = val.replace(/\\/g, "\\\\");
+            for (var p in replacements) {
+                var replace = "\\" + replacements[p];
+                val = val.replace(RegExp(String.fromCharCode(p), "g"), replace);
+            }
+            return '"' + val.replace(/"/g, '\\"') + '"';
+        case "boolean":
+        case "undefined":
+            return String(val);
+        case "number":
+            // In JavaScript, -0 === 0 and String(-0) == "0", so we have to
+            // special-case.
+            if (val === -0 && 1/val === -Infinity) {
+                return "-0";
+            }
+            return String(val);
+        case "object":
+            if (val === null) {
+                return "null";
+            }
+
+            // Special-case Node objects, since those come up a lot in my tests.  I
+            // ignore namespaces.
+            if (is_node(val)) {
+                switch (val.nodeType) {
+                case Node.ELEMENT_NODE:
+                    var ret = "<" + val.localName;
+                    for (var i = 0; i < val.attributes.length; i++) {
+                        ret += " " + val.attributes[i].name + '="' + val.attributes[i].value + '"';
+                    }
+                    ret += ">" + val.innerHTML + "</" + val.localName + ">";
+                    return "Element node " + truncate(ret, 60);
+                case Node.TEXT_NODE:
+                    return 'Text node "' + truncate(val.data, 60) + '"';
+                case Node.PROCESSING_INSTRUCTION_NODE:
+                    return "ProcessingInstruction node with target " + format_value(truncate(val.target, 60)) + " and data " + format_value(truncate(val.data, 60));
+                case Node.COMMENT_NODE:
+                    return "Comment node <!--" + truncate(val.data, 60) + "-->";
+                case Node.DOCUMENT_NODE:
+                    return "Document node with " + val.childNodes.length + (val.childNodes.length == 1 ? " child" : " children");
+                case Node.DOCUMENT_TYPE_NODE:
+                    return "DocumentType node";
+                case Node.DOCUMENT_FRAGMENT_NODE:
+                    return "DocumentFragment node with " + val.childNodes.length + (val.childNodes.length == 1 ? " child" : " children");
+                default:
+                    return "Node object of unknown type";
+                }
+            }
+
+        /* falls through */
+        default:
+            try {
+                return typeof val + ' "' + truncate(String(val), 1000) + '"';
+            } catch(e) {
+                return ("[stringifying object threw " + String(e) +
+                        " with type " + String(typeof e) + "]");
+            }
+        }
+    }
+    expose(format_value, "format_value");
+
+    /*
+     * Assertions
+     */
+
+    function expose_assert(f, name) {
+        function assert_wrapper(...args) {
+            let status = Test.statuses.TIMEOUT;
+            let stack = null;
+            let new_assert_index = null;
+            try {
+                if (settings.debug) {
+                    console.debug("ASSERT", name, tests.current_test && tests.current_test.name, args);
+                }
+                if (tests.output) {
+                    tests.set_assert(name, args);
+                    // Remember the newly pushed assert's index, because `apply`
+                    // below might push new asserts.
+                    new_assert_index = tests.asserts_run.length - 1;
+                }
+                const rv = f.apply(undefined, args);
+                status = Test.statuses.PASS;
+                return rv;
+            } catch(e) {
+                status = Test.statuses.FAIL;
+                stack = e.stack ? e.stack : null;
+                throw e;
+            } finally {
+                if (tests.output && !stack) {
+                    stack = get_stack();
+                }
+                if (tests.output) {
+                    tests.set_assert_status(new_assert_index, status, stack);
+                }
+            }
+        }
+        expose(assert_wrapper, name);
+    }
+
+    /**
+     * Assert that ``actual`` is strictly true
+     *
+     * @param {Any} actual - Value that is asserted to be true
+     * @param {string} [description] - Description of the condition being tested
+     */
+    function assert_true(actual, description)
+    {
+        assert(actual === true, "assert_true", description,
+                                "expected true got ${actual}", {actual:actual});
+    }
+    expose_assert(assert_true, "assert_true");
+
+    /**
+     * Assert that ``actual`` is strictly false
+     *
+     * @param {Any} actual - Value that is asserted to be false
+     * @param {string} [description] - Description of the condition being tested
+     */
+    function assert_false(actual, description)
+    {
+        assert(actual === false, "assert_false", description,
+                                 "expected false got ${actual}", {actual:actual});
+    }
+    expose_assert(assert_false, "assert_false");
+
+    function same_value(x, y) {
+        if (y !== y) {
+            //NaN case
+            return x !== x;
+        }
+        if (x === 0 && y === 0) {
+            //Distinguish +0 and -0
+            return 1/x === 1/y;
+        }
+        return x === y;
+    }
+
+    /**
+     * Assert that ``actual`` is the same value as ``expected``.
+     *
+     * For objects this compares by cobject identity; for primitives
+     * this distinguishes between 0 and -0, and has correct handling
+     * of NaN.
+     *
+     * @param {Any} actual - Test value.
+     * @param {Any} expected - Expected value.
+     * @param {string} [description] - Description of the condition being tested.
+     */
+    function assert_equals(actual, expected, description)
+    {
+         /*
+          * Test if two primitives are equal or two objects
+          * are the same object
+          */
+        if (typeof actual != typeof expected) {
+            assert(false, "assert_equals", description,
+                          "expected (" + typeof expected + ") ${expected} but got (" + typeof actual + ") ${actual}",
+                          {expected:expected, actual:actual});
+            return;
+        }
+        assert(same_value(actual, expected), "assert_equals", description,
+                                             "expected ${expected} but got ${actual}",
+                                             {expected:expected, actual:actual});
+    }
+    expose_assert(assert_equals, "assert_equals");
+
+    /**
+     * Assert that ``actual`` is not the same value as ``expected``.
+     *
+     * Comparison is as for :js:func:`assert_equals`.
+     *
+     * @param {Any} actual - Test value.
+     * @param {Any} expected - The value ``actual`` is expected to be different to.
+     * @param {string} [description] - Description of the condition being tested.
+     */
+    function assert_not_equals(actual, expected, description)
+    {
+        assert(!same_value(actual, expected), "assert_not_equals", description,
+                                              "got disallowed value ${actual}",
+                                              {actual:actual});
+    }
+    expose_assert(assert_not_equals, "assert_not_equals");
+
+    /**
+     * Assert that ``expected`` is an array and ``actual`` is one of the members.
+     * This is implemented using ``indexOf``, so doesn't handle NaN or ±0 correctly.
+     *
+     * @param {Any} actual - Test value.
+     * @param {Array} expected - An array that ``actual`` is expected to
+     * be a member of.
+     * @param {string} [description] - Description of the condition being tested.
+     */
+    function assert_in_array(actual, expected, description)
+    {
+        assert(expected.indexOf(actual) != -1, "assert_in_array", description,
+                                               "value ${actual} not in array ${expected}",
+                                               {actual:actual, expected:expected});
+    }
+    expose_assert(assert_in_array, "assert_in_array");
+
+    // This function was deprecated in July of 2015.
+    // See https://github.com/web-platform-tests/wpt/issues/2033
+    /**
+     * @deprecated
+     * Recursively compare two objects for equality.
+     *
+     * See `Issue 2033
+     * <https://github.com/web-platform-tests/wpt/issues/2033>`_ for
+     * more information.
+     *
+     * @param {Object} actual - Test value.
+     * @param {Object} expected - Expected value.
+     * @param {string} [description] - Description of the condition being tested.
+     */
+    function assert_object_equals(actual, expected, description)
+    {
+         assert(typeof actual === "object" && actual !== null, "assert_object_equals", description,
+                                                               "value is ${actual}, expected object",
+                                                               {actual: actual});
+         //This needs to be improved a great deal
+         function check_equal(actual, expected, stack)
+         {
+             stack.push(actual);
+
+             var p;
+             for (p in actual) {
+                 assert(expected.hasOwnProperty(p), "assert_object_equals", description,
+                                                    "unexpected property ${p}", {p:p});
+
+                 if (typeof actual[p] === "object" && actual[p] !== null) {
+                     if (stack.indexOf(actual[p]) === -1) {
+                         check_equal(actual[p], expected[p], stack);
+                     }
+                 } else {
+                     assert(same_value(actual[p], expected[p]), "assert_object_equals", description,
+                                                       "property ${p} expected ${expected} got ${actual}",
+                                                       {p:p, expected:expected[p], actual:actual[p]});
+                 }
+             }
+             for (p in expected) {
+                 assert(actual.hasOwnProperty(p),
+                        "assert_object_equals", description,
+                        "expected property ${p} missing", {p:p});
+             }
+             stack.pop();
+         }
+         check_equal(actual, expected, []);
+    }
+    expose_assert(assert_object_equals, "assert_object_equals");
+
+    /**
+     * Assert that ``actual`` and ``expected`` are both arrays, and that the array properties of
+     * ``actual`` and ``expected`` are all the same value (as for :js:func:`assert_equals`).
+     *
+     * @param {Array} actual - Test array.
+     * @param {Array} expected - Array that is expected to contain the same values as ``actual``.
+     * @param {string} [description] - Description of the condition being tested.
+     */
+    function assert_array_equals(actual, expected, description)
+    {
+        const max_array_length = 20;
+        function shorten_array(arr, offset = 0) {
+            // Make ", …" only show up when it would likely reduce the length, not accounting for
+            // fonts.
+            if (arr.length < max_array_length + 2) {
+                return arr;
+            }
+            // By default we want half the elements after the offset and half before
+            // But if that takes us past the end of the array, we have more before, and
+            // if it takes us before the start we have more after.
+            const length_after_offset = Math.floor(max_array_length / 2);
+            let upper_bound = Math.min(length_after_offset + offset, arr.length);
+            const lower_bound = Math.max(upper_bound - max_array_length, 0);
+
+            if (lower_bound === 0) {
+                upper_bound = max_array_length;
+            }
+
+            const output = arr.slice(lower_bound, upper_bound);
+            if (lower_bound > 0) {
+                output.beginEllipsis = true;
+            }
+            if (upper_bound < arr.length) {
+                output.endEllipsis = true;
+            }
+            return output;
+        }
+
+        assert(typeof actual === "object" && actual !== null && "length" in actual,
+               "assert_array_equals", description,
+               "value is ${actual}, expected array",
+               {actual:actual});
+        assert(actual.length === expected.length,
+               "assert_array_equals", description,
+               "lengths differ, expected array ${expected} length ${expectedLength}, got ${actual} length ${actualLength}",
+               {expected:shorten_array(expected, expected.length - 1), expectedLength:expected.length,
+                actual:shorten_array(actual, actual.length - 1), actualLength:actual.length
+               });
+
+        for (var i = 0; i < actual.length; i++) {
+            assert(actual.hasOwnProperty(i) === expected.hasOwnProperty(i),
+                   "assert_array_equals", description,
+                   "expected property ${i} to be ${expected} but was ${actual} (expected array ${arrayExpected} got ${arrayActual})",
+                   {i:i, expected:expected.hasOwnProperty(i) ? "present" : "missing",
+                    actual:actual.hasOwnProperty(i) ? "present" : "missing",
+                    arrayExpected:shorten_array(expected, i), arrayActual:shorten_array(actual, i)});
+            assert(same_value(expected[i], actual[i]),
+                   "assert_array_equals", description,
+                   "expected property ${i} to be ${expected} but got ${actual} (expected array ${arrayExpected} got ${arrayActual})",
+                   {i:i, expected:expected[i], actual:actual[i],
+                    arrayExpected:shorten_array(expected, i), arrayActual:shorten_array(actual, i)});
+        }
+    }
+    expose_assert(assert_array_equals, "assert_array_equals");
+
+    /**
+     * Assert that each array property in ``actual`` is a number within
+     * ± `epsilon` of the corresponding property in `expected`.
+     *
+     * @param {Array} actual - Array of test values.
+     * @param {Array} expected - Array of values expected to be close to the values in ``actual``.
+     * @param {number} epsilon - Magnitude of allowed difference
+     * between each value in ``actual`` and ``expected``.
+     * @param {string} [description] - Description of the condition being tested.
+     */
+    function assert_array_approx_equals(actual, expected, epsilon, description)
+    {
+        /*
+         * Test if two primitive arrays are equal within +/- epsilon
+         */
+        assert(actual.length === expected.length,
+               "assert_array_approx_equals", description,
+               "lengths differ, expected ${expected} got ${actual}",
+               {expected:expected.length, actual:actual.length});
+
+        for (var i = 0; i < actual.length; i++) {
+            assert(actual.hasOwnProperty(i) === expected.hasOwnProperty(i),
+                   "assert_array_approx_equals", description,
+                   "property ${i}, property expected to be ${expected} but was ${actual}",
+                   {i:i, expected:expected.hasOwnProperty(i) ? "present" : "missing",
+                    actual:actual.hasOwnProperty(i) ? "present" : "missing"});
+            assert(typeof actual[i] === "number",
+                   "assert_array_approx_equals", description,
+                   "property ${i}, expected a number but got a ${type_actual}",
+                   {i:i, type_actual:typeof actual[i]});
+            assert(Math.abs(actual[i] - expected[i]) <= epsilon,
+                   "assert_array_approx_equals", description,
+                   "property ${i}, expected ${expected} +/- ${epsilon}, expected ${expected} but got ${actual}",
+                   {i:i, expected:expected[i], actual:actual[i], epsilon:epsilon});
+        }
+    }
+    expose_assert(assert_array_approx_equals, "assert_array_approx_equals");
+
+    /**
+     * Assert that ``actual`` is within ± ``epsilon`` of ``expected``.
+     *
+     * @param {number} actual - Test value.
+     * @param {number} expected - Value number is expected to be close to.
+     * @param {number} epsilon - Magnitude of allowed difference between ``actual`` and ``expected``.
+     * @param {string} [description] - Description of the condition being tested.
+     */
+    function assert_approx_equals(actual, expected, epsilon, description)
+    {
+        /*
+         * Test if two primitive numbers are equal within +/- epsilon
+         */
+        assert(typeof actual === "number",
+               "assert_approx_equals", description,
+               "expected a number but got a ${type_actual}",
+               {type_actual:typeof actual});
+
+        // The epsilon math below does not place nice with NaN and Infinity
+        // But in this case Infinity = Infinity and NaN = NaN
+        if (isFinite(actual) || isFinite(expected)) {
+            assert(Math.abs(actual - expected) <= epsilon,
+                   "assert_approx_equals", description,
+                   "expected ${expected} +/- ${epsilon} but got ${actual}",
+                   {expected:expected, actual:actual, epsilon:epsilon});
+        } else {
+            assert_equals(actual, expected);
+        }
+    }
+    expose_assert(assert_approx_equals, "assert_approx_equals");
+
+    /**
+     * Assert that ``actual`` is a number less than ``expected``.
+     *
+     * @param {number} actual - Test value.
+     * @param {number} expected - Number that ``actual`` must be less than.
+     * @param {string} [description] - Description of the condition being tested.
+     */
+    function assert_less_than(actual, expected, description)
+    {
+        /*
+         * Test if a primitive number is less than another
+         */
+        assert(typeof actual === "number",
+               "assert_less_than", description,
+               "expected a number but got a ${type_actual}",
+               {type_actual:typeof actual});
+
+        assert(actual < expected,
+               "assert_less_than", description,
+               "expected a number less than ${expected} but got ${actual}",
+               {expected:expected, actual:actual});
+    }
+    expose_assert(assert_less_than, "assert_less_than");
+
+    /**
+     * Assert that ``actual`` is a number greater than ``expected``.
+     *
+     * @param {number} actual - Test value.
+     * @param {number} expected - Number that ``actual`` must be greater than.
+     * @param {string} [description] - Description of the condition being tested.
+     */
+    function assert_greater_than(actual, expected, description)
+    {
+        /*
+         * Test if a primitive number is greater than another
+         */
+        assert(typeof actual === "number",
+               "assert_greater_than", description,
+               "expected a number but got a ${type_actual}",
+               {type_actual:typeof actual});
+
+        assert(actual > expected,
+               "assert_greater_than", description,
+               "expected a number greater than ${expected} but got ${actual}",
+               {expected:expected, actual:actual});
+    }
+    expose_assert(assert_greater_than, "assert_greater_than");
+
+    /**
+     * Assert that ``actual`` is a number greater than ``lower`` and less
+     * than ``upper`` but not equal to either.
+     *
+     * @param {number} actual - Test value.
+     * @param {number} lower - Number that ``actual`` must be greater than.
+     * @param {number} upper - Number that ``actual`` must be less than.
+     * @param {string} [description] - Description of the condition being tested.
+     */
+    function assert_between_exclusive(actual, lower, upper, description)
+    {
+        /*
+         * Test if a primitive number is between two others
+         */
+        assert(typeof actual === "number",
+               "assert_between_exclusive", description,
+               "expected a number but got a ${type_actual}",
+               {type_actual:typeof actual});
+
+        assert(actual > lower && actual < upper,
+               "assert_between_exclusive", description,
+               "expected a number greater than ${lower} " +
+               "and less than ${upper} but got ${actual}",
+               {lower:lower, upper:upper, actual:actual});
+    }
+    expose_assert(assert_between_exclusive, "assert_between_exclusive");
+
+    /**
+     * Assert that ``actual`` is a number less than or equal to ``expected``.
+     *
+     * @param {number} actual - Test value.
+     * @param {number} expected - Number that ``actual`` must be less
+     * than or equal to.
+     * @param {string} [description] - Description of the condition being tested.
+     */
+    function assert_less_than_equal(actual, expected, description)
+    {
+        /*
+         * Test if a primitive number is less than or equal to another
+         */
+        assert(typeof actual === "number",
+               "assert_less_than_equal", description,
+               "expected a number but got a ${type_actual}",
+               {type_actual:typeof actual});
+
+        assert(actual <= expected,
+               "assert_less_than_equal", description,
+               "expected a number less than or equal to ${expected} but got ${actual}",
+               {expected:expected, actual:actual});
+    }
+    expose_assert(assert_less_than_equal, "assert_less_than_equal");
+
+    /**
+     * Assert that ``actual`` is a number greater than or equal to ``expected``.
+     *
+     * @param {number} actual - Test value.
+     * @param {number} expected - Number that ``actual`` must be greater
+     * than or equal to.
+     * @param {string} [description] - Description of the condition being tested.
+     */
+    function assert_greater_than_equal(actual, expected, description)
+    {
+        /*
+         * Test if a primitive number is greater than or equal to another
+         */
+        assert(typeof actual === "number",
+               "assert_greater_than_equal", description,
+               "expected a number but got a ${type_actual}",
+               {type_actual:typeof actual});
+
+        assert(actual >= expected,
+               "assert_greater_than_equal", description,
+               "expected a number greater than or equal to ${expected} but got ${actual}",
+               {expected:expected, actual:actual});
+    }
+    expose_assert(assert_greater_than_equal, "assert_greater_than_equal");
+
+    /**
+     * Assert that ``actual`` is a number greater than or equal to ``lower`` and less
+     * than or equal to ``upper``.
+     *
+     * @param {number} actual - Test value.
+     * @param {number} lower - Number that ``actual`` must be greater than or equal to.
+     * @param {number} upper - Number that ``actual`` must be less than or equal to.
+     * @param {string} [description] - Description of the condition being tested.
+     */
+    function assert_between_inclusive(actual, lower, upper, description)
+    {
+        /*
+         * Test if a primitive number is between to two others or equal to either of them
+         */
+        assert(typeof actual === "number",
+               "assert_between_inclusive", description,
+               "expected a number but got a ${type_actual}",
+               {type_actual:typeof actual});
+
+        assert(actual >= lower && actual <= upper,
+               "assert_between_inclusive", description,
+               "expected a number greater than or equal to ${lower} " +
+               "and less than or equal to ${upper} but got ${actual}",
+               {lower:lower, upper:upper, actual:actual});
+    }
+    expose_assert(assert_between_inclusive, "assert_between_inclusive");
+
+    /**
+     * Assert that ``actual`` matches the RegExp ``expected``.
+     *
+     * @param {String} actual - Test string.
+     * @param {RegExp} expected - RegExp ``actual`` must match.
+     * @param {string} [description] - Description of the condition being tested.
+     */
+    function assert_regexp_match(actual, expected, description) {
+        /*
+         * Test if a string (actual) matches a regexp (expected)
+         */
+        assert(expected.test(actual),
+               "assert_regexp_match", description,
+               "expected ${expected} but got ${actual}",
+               {expected:expected, actual:actual});
+    }
+    expose_assert(assert_regexp_match, "assert_regexp_match");
+
+    /**
+     * Assert that the class string of ``object`` as returned in
+     * ``Object.prototype.toString`` is equal to ``class_name``.
+     *
+     * @param {Object} object - Object to stringify.
+     * @param {string} class_string - Expected class string for ``object``.
+     * @param {string} [description] - Description of the condition being tested.
+     */
+    function assert_class_string(object, class_string, description) {
+        var actual = {}.toString.call(object);
+        var expected = "[object " + class_string + "]";
+        assert(same_value(actual, expected), "assert_class_string", description,
+                                             "expected ${expected} but got ${actual}",
+                                             {expected:expected, actual:actual});
+    }
+    expose_assert(assert_class_string, "assert_class_string");
+
+    /**
+     * Assert that ``object`` has an own property with name ``property_name``.
+     *
+     * @param {Object} object - Object that should have the given property.
+     * @param {string} property_name - Expected property name.
+     * @param {string} [description] - Description of the condition being tested.
+     */
+    function assert_own_property(object, property_name, description) {
+        assert(object.hasOwnProperty(property_name),
+               "assert_own_property", description,
+               "expected property ${p} missing", {p:property_name});
+    }
+    expose_assert(assert_own_property, "assert_own_property");
+
+    /**
+     * Assert that ``object`` does not have an own property with name ``property_name``.
+     *
+     * @param {Object} object - Object that should not have the given property.
+     * @param {string} property_name - Property name to test.
+     * @param {string} [description] - Description of the condition being tested.
+     */
+    function assert_not_own_property(object, property_name, description) {
+        assert(!object.hasOwnProperty(property_name),
+               "assert_not_own_property", description,
+               "unexpected property ${p} is found on object", {p:property_name});
+    }
+    expose_assert(assert_not_own_property, "assert_not_own_property");
+
+    function _assert_inherits(name) {
+        return function (object, property_name, description)
+        {
+            assert((typeof object === "object" && object !== null) ||
+                   typeof object === "function" ||
+                   // Or has [[IsHTMLDDA]] slot
+                   String(object) === "[object HTMLAllCollection]",
+                   name, description,
+                   "provided value is not an object");
+
+            assert("hasOwnProperty" in object,
+                   name, description,
+                   "provided value is an object but has no hasOwnProperty method");
+
+            assert(!object.hasOwnProperty(property_name),
+                   name, description,
+                   "property ${p} found on object expected in prototype chain",
+                   {p:property_name});
+
+            assert(property_name in object,
+                   name, description,
+                   "property ${p} not found in prototype chain",
+                   {p:property_name});
+        };
+    }
+
+    /**
+     * Assert that ``object`` does not have an own property with name
+     * ``property_name``, but inherits one through the prototype chain.
+     *
+     * @param {Object} object - Object that should have the given property in its prototype chain.
+     * @param {string} property_name - Expected property name.
+     * @param {string} [description] - Description of the condition being tested.
+     */
+    function assert_inherits(object, property_name, description) {
+        return _assert_inherits("assert_inherits")(object, property_name, description);
+    }
+    expose_assert(assert_inherits, "assert_inherits");
+
+    /**
+     * Alias for :js:func:`insert_inherits`.
+     *
+     * @param {Object} object - Object that should have the given property in its prototype chain.
+     * @param {string} property_name - Expected property name.
+     * @param {string} [description] - Description of the condition being tested.
+     */
+    function assert_idl_attribute(object, property_name, description) {
+        return _assert_inherits("assert_idl_attribute")(object, property_name, description);
+    }
+    expose_assert(assert_idl_attribute, "assert_idl_attribute");
+
+
+    /**
+     * Assert that ``object`` has a property named ``property_name`` and that the property is readonly.
+     *
+     * Note: The implementation tries to update the named property, so
+     * any side effects of updating will be triggered. Users are
+     * encouraged to instead inspect the property descriptor of ``property_name`` on ``object``.
+     *
+     * @param {Object} object - Object that should have the given property in its prototype chain.
+     * @param {string} property_name - Expected property name.
+     * @param {string} [description] - Description of the condition being tested.
+     */
+    function assert_readonly(object, property_name, description)
+    {
+         var initial_value = object[property_name];
+         try {
+             //Note that this can have side effects in the case where
+             //the property has PutForwards
+             object[property_name] = initial_value + "a"; //XXX use some other value here?
+             assert(same_value(object[property_name], initial_value),
+                    "assert_readonly", description,
+                    "changing property ${p} succeeded",
+                    {p:property_name});
+         } finally {
+             object[property_name] = initial_value;
+         }
+    }
+    expose_assert(assert_readonly, "assert_readonly");
+
+    /**
+     * Assert a JS Error with the expected constructor is thrown.
+     *
+     * @param {object} constructor The expected exception constructor.
+     * @param {Function} func Function which should throw.
+     * @param {string} [description] Error description for the case that the error is not thrown.
+     */
+    function assert_throws_js(constructor, func, description)
+    {
+        assert_throws_js_impl(constructor, func, description,
+                              "assert_throws_js");
+    }
+    expose_assert(assert_throws_js, "assert_throws_js");
+
+    /**
+     * Like assert_throws_js but allows specifying the assertion type
+     * (assert_throws_js or promise_rejects_js, in practice).
+     */
+    function assert_throws_js_impl(constructor, func, description,
+                                   assertion_type)
+    {
+        try {
+            func.call(this);
+            assert(false, assertion_type, description,
+                   "${func} did not throw", {func:func});
+        } catch (e) {
+            if (e instanceof AssertionError) {
+                throw e;
+            }
+
+            // Basic sanity-checks on the thrown exception.
+            assert(typeof e === "object",
+                   assertion_type, description,
+                   "${func} threw ${e} with type ${type}, not an object",
+                   {func:func, e:e, type:typeof e});
+
+            assert(e !== null,
+                   assertion_type, description,
+                   "${func} threw null, not an object",
+                   {func:func});
+
+            // Basic sanity-check on the passed-in constructor
+            assert(typeof constructor == "function",
+                   assertion_type, description,
+                   "${constructor} is not a constructor",
+                   {constructor:constructor});
+            var obj = constructor;
+            while (obj) {
+                if (typeof obj === "function" &&
+                    obj.name === "Error") {
+                    break;
+                }
+                obj = Object.getPrototypeOf(obj);
+            }
+            assert(obj != null,
+                   assertion_type, description,
+                   "${constructor} is not an Error subtype",
+                   {constructor:constructor});
+
+            // And checking that our exception is reasonable
+            assert(e.constructor === constructor &&
+                   e.name === constructor.name,
+                   assertion_type, description,
+                   "${func} threw ${actual} (${actual_name}) expected instance of ${expected} (${expected_name})",
+                   {func:func, actual:e, actual_name:e.name,
+                    expected:constructor,
+                    expected_name:constructor.name});
+        }
+    }
+
+    // TODO: Figure out how to document the overloads better.
+    // sphinx-js doesn't seem to handle @variation correctly,
+    // and only expects a single JSDoc entry per function.
+    /**
+     * Assert a DOMException with the expected type is thrown.
+     *
+     * There are two ways of calling assert_throws_dom:
+     *
+     * 1) If the DOMException is expected to come from the current global, the
+     * second argument should be the function expected to throw and a third,
+     * optional, argument is the assertion description.
+     *
+     * 2) If the DOMException is expected to come from some other global, the
+     * second argument should be the DOMException constructor from that global,
+     * the third argument the function expected to throw, and the fourth, optional,
+     * argument the assertion description.
+     *
+     * @param {number|string} type - The expected exception name or
+     * code.  See the `table of names and codes
+     * <https://webidl.spec.whatwg.org/#dfn-error-names-table>`_. If a
+     * number is passed it should be one of the numeric code values in
+     * that table (e.g. 3, 4, etc).  If a string is passed it can
+     * either be an exception name (e.g. "HierarchyRequestError",
+     * "WrongDocumentError") or the name of the corresponding error
+     * code (e.g. "``HIERARCHY_REQUEST_ERR``", "``WRONG_DOCUMENT_ERR``").
+     * @param {Function} descriptionOrFunc - The function expected to
+     * throw (if the exception comes from another global), or the
+     * optional description of the condition being tested (if the
+     * exception comes from the current global).
+     * @param {string} [description] - Description of the condition
+     * being tested (if the exception comes from another global).
+     *
+     */
+    function assert_throws_dom(type, funcOrConstructor, descriptionOrFunc, maybeDescription)
+    {
+        let constructor, func, description;
+        if (funcOrConstructor.name === "DOMException") {
+            constructor = funcOrConstructor;
+            func = descriptionOrFunc;
+            description = maybeDescription;
+        } else {
+            constructor = self.DOMException;
+            func = funcOrConstructor;
+            description = descriptionOrFunc;
+            assert(maybeDescription === undefined,
+                   "Too many args pased to no-constructor version of assert_throws_dom");
+        }
+        assert_throws_dom_impl(type, func, description, "assert_throws_dom", constructor)
+    }
+    expose_assert(assert_throws_dom, "assert_throws_dom");
+
+    /**
+     * Similar to assert_throws_dom but allows specifying the assertion type
+     * (assert_throws_dom or promise_rejects_dom, in practice).  The
+     * "constructor" argument must be the DOMException constructor from the
+     * global we expect the exception to come from.
+     */
+    function assert_throws_dom_impl(type, func, description, assertion_type, constructor)
+    {
+        try {
+            func.call(this);
+            assert(false, assertion_type, description,
+                   "${func} did not throw", {func:func});
+        } catch (e) {
+            if (e instanceof AssertionError) {
+                throw e;
+            }
+
+            // Basic sanity-checks on the thrown exception.
+            assert(typeof e === "object",
+                   assertion_type, description,
+                   "${func} threw ${e} with type ${type}, not an object",
+                   {func:func, e:e, type:typeof e});
+
+            assert(e !== null,
+                   assertion_type, description,
+                   "${func} threw null, not an object",
+                   {func:func});
+
+            // Sanity-check our type
+            assert(typeof type == "number" ||
+                   typeof type == "string",
+                   assertion_type, description,
+                   "${type} is not a number or string",
+                   {type:type});
+
+            var codename_name_map = {
+                INDEX_SIZE_ERR: 'IndexSizeError',
+                HIERARCHY_REQUEST_ERR: 'HierarchyRequestError',
+                WRONG_DOCUMENT_ERR: 'WrongDocumentError',
+                INVALID_CHARACTER_ERR: 'InvalidCharacterError',
+                NO_MODIFICATION_ALLOWED_ERR: 'NoModificationAllowedError',
+                NOT_FOUND_ERR: 'NotFoundError',
+                NOT_SUPPORTED_ERR: 'NotSupportedError',
+                INUSE_ATTRIBUTE_ERR: 'InUseAttributeError',
+                INVALID_STATE_ERR: 'InvalidStateError',
+                SYNTAX_ERR: 'SyntaxError',
+                INVALID_MODIFICATION_ERR: 'InvalidModificationError',
+                NAMESPACE_ERR: 'NamespaceError',
+                INVALID_ACCESS_ERR: 'InvalidAccessError',
+                TYPE_MISMATCH_ERR: 'TypeMismatchError',
+                SECURITY_ERR: 'SecurityError',
+                NETWORK_ERR: 'NetworkError',
+                ABORT_ERR: 'AbortError',
+                URL_MISMATCH_ERR: 'URLMismatchError',
+                QUOTA_EXCEEDED_ERR: 'QuotaExceededError',
+                TIMEOUT_ERR: 'TimeoutError',
+                INVALID_NODE_TYPE_ERR: 'InvalidNodeTypeError',
+                DATA_CLONE_ERR: 'DataCloneError'
+            };
+
+            var name_code_map = {
+                IndexSizeError: 1,
+                HierarchyRequestError: 3,
+                WrongDocumentError: 4,
+                InvalidCharacterError: 5,
+                NoModificationAllowedError: 7,
+                NotFoundError: 8,
+                NotSupportedError: 9,
+                InUseAttributeError: 10,
+                InvalidStateError: 11,
+                SyntaxError: 12,
+                InvalidModificationError: 13,
+                NamespaceError: 14,
+                InvalidAccessError: 15,
+                TypeMismatchError: 17,
+                SecurityError: 18,
+                NetworkError: 19,
+                AbortError: 20,
+                URLMismatchError: 21,
+                QuotaExceededError: 22,
+                TimeoutError: 23,
+                InvalidNodeTypeError: 24,
+                DataCloneError: 25,
+
+                EncodingError: 0,
+                NotReadableError: 0,
+                UnknownError: 0,
+                ConstraintError: 0,
+                DataError: 0,
+                TransactionInactiveError: 0,
+                ReadOnlyError: 0,
+                VersionError: 0,
+                OperationError: 0,
+                NotAllowedError: 0,
+                OptOutError: 0
+            };
+
+            var code_name_map = {};
+            for (var key in name_code_map) {
+                if (name_code_map[key] > 0) {
+                    code_name_map[name_code_map[key]] = key;
+                }
+            }
+
+            var required_props = {};
+            var name;
+
+            if (typeof type === "number") {
+                if (type === 0) {
+                    throw new AssertionError('Test bug: ambiguous DOMException code 0 passed to assert_throws_dom()');
+                } else if (!(type in code_name_map)) {
+                    throw new AssertionError('Test bug: unrecognized DOMException code "' + type + '" passed to assert_throws_dom()');
+                }
+                name = code_name_map[type];
+                required_props.code = type;
+            } else if (typeof type === "string") {
+                name = type in codename_name_map ? codename_name_map[type] : type;
+                if (!(name in name_code_map)) {
+                    throw new AssertionError('Test bug: unrecognized DOMException code name or name "' + type + '" passed to assert_throws_dom()');
+                }
+
+                required_props.code = name_code_map[name];
+            }
+
+            if (required_props.code === 0 ||
+               ("name" in e &&
+                e.name !== e.name.toUpperCase() &&
+                e.name !== "DOMException")) {
+                // New style exception: also test the name property.
+                required_props.name = name;
+            }
+
+            for (var prop in required_props) {
+                assert(prop in e && e[prop] == required_props[prop],
+                       assertion_type, description,
+                       "${func} threw ${e} that is not a DOMException " + type + ": property ${prop} is equal to ${actual}, expected ${expected}",
+                       {func:func, e:e, prop:prop, actual:e[prop], expected:required_props[prop]});
+            }
+
+            // Check that the exception is from the right global.  This check is last
+            // so more specific, and more informative, checks on the properties can
+            // happen in case a totally incorrect exception is thrown.
+            assert(e.constructor === constructor,
+                   assertion_type, description,
+                   "${func} threw an exception from the wrong global",
+                   {func});
+
+        }
+    }
+
+    /**
+     * Assert the provided value is thrown.
+     *
+     * @param {value} exception The expected exception.
+     * @param {Function} func Function which should throw.
+     * @param {string} [description] Error description for the case that the error is not thrown.
+     */
+    function assert_throws_exactly(exception, func, description)
+    {
+        assert_throws_exactly_impl(exception, func, description,
+                                   "assert_throws_exactly");
+    }
+    expose_assert(assert_throws_exactly, "assert_throws_exactly");
+
+    /**
+     * Like assert_throws_exactly but allows specifying the assertion type
+     * (assert_throws_exactly or promise_rejects_exactly, in practice).
+     */
+    function assert_throws_exactly_impl(exception, func, description,
+                                        assertion_type)
+    {
+        try {
+            func.call(this);
+            assert(false, assertion_type, description,
+                   "${func} did not throw", {func:func});
+        } catch (e) {
+            if (e instanceof AssertionError) {
+                throw e;
+            }
+
+            assert(same_value(e, exception), assertion_type, description,
+                   "${func} threw ${e} but we expected it to throw ${exception}",
+                   {func:func, e:e, exception:exception});
+        }
+    }
+
+    /**
+     * Asserts if called. Used to ensure that a specific codepath is
+     * not taken e.g. that an error event isn't fired.
+     *
+     * @param {string} [description] - Description of the condition being tested.
+     */
+    function assert_unreached(description) {
+         assert(false, "assert_unreached", description,
+                "Reached unreachable code");
+    }
+    expose_assert(assert_unreached, "assert_unreached");
+
+    /**
+     * @callback AssertFunc
+     * @param {Any} actual
+     * @param {Any} expected
+     * @param {Any[]} args
+     */
+
+    /**
+     * Asserts that ``actual`` matches at least one value of ``expected``
+     * according to a comparison defined by ``assert_func``.
+     *
+     * Note that tests with multiple allowed pass conditions are bad
+     * practice unless the spec specifically allows multiple
+     * behaviours. Test authors should not use this method simply to
+     * hide UA bugs.
+     *
+     * @param {AssertFunc} assert_func - Function to compare actual
+     * and expected. It must throw when the comparison fails and
+     * return when the comparison passes.
+     * @param {Any} actual - Test value.
+     * @param {Array} expected_array - Array of possible expected values.
+     * @param {Any[]} args - Additional arguments to pass to ``assert_func``.
+     */
+    function assert_any(assert_func, actual, expected_array, ...args)
+    {
+        var errors = [];
+        var passed = false;
+        forEach(expected_array,
+                function(expected)
+                {
+                    try {
+                        assert_func.apply(this, [actual, expected].concat(args));
+                        passed = true;
+                    } catch (e) {
+                        errors.push(e.message);
+                    }
+                });
+        if (!passed) {
+            throw new AssertionError(errors.join("\n\n"));
+        }
+    }
+    // FIXME: assert_any cannot use expose_assert, because assert_wrapper does
+    // not support nested assert calls (e.g. to assert_func). We need to
+    // support bypassing assert_wrapper for the inner asserts here.
+    expose(assert_any, "assert_any");
+
+    /**
+     * Assert that a feature is implemented, based on a 'truthy' condition.
+     *
+     * This function should be used to early-exit from tests in which there is
+     * no point continuing without support for a non-optional spec or spec
+     * feature. For example:
+     *
+     *     assert_implements(window.Foo, 'Foo is not supported');
+     *
+     * @param {object} condition The truthy value to test
+     * @param {string} [description] Error description for the case that the condition is not truthy.
+     */
+    function assert_implements(condition, description) {
+        assert(!!condition, "assert_implements", description);
+    }
+    expose_assert(assert_implements, "assert_implements")
+
+    /**
+     * Assert that an optional feature is implemented, based on a 'truthy' condition.
+     *
+     * This function should be used to early-exit from tests in which there is
+     * no point continuing without support for an explicitly optional spec or
+     * spec feature. For example:
+     *
+     *     assert_implements_optional(video.canPlayType("video/webm"),
+     *                                "webm video playback not supported");
+     *
+     * @param {object} condition The truthy value to test
+     * @param {string} [description] Error description for the case that the condition is not truthy.
+     */
+    function assert_implements_optional(condition, description) {
+        if (!condition) {
+            throw new OptionalFeatureUnsupportedError(description);
+        }
+    }
+    expose_assert(assert_implements_optional, "assert_implements_optional");
+
+    /**
+     * @class
+     *
+     * A single subtest. A Test is not constructed directly but via the
+     * :js:func:`test`, :js:func:`async_test` or :js:func:`promise_test` functions.
+     *
+     * @param {string} name - This must be unique in a given file and must be
+     * invariant between runs.
+     *
+     */
+    function Test(name, properties)
+    {
+        if (tests.file_is_test && tests.tests.length) {
+            throw new Error("Tried to create a test with file_is_test");
+        }
+        /** The test name. */
+        this.name = name;
+
+        this.phase = (tests.is_aborted || tests.phase === tests.phases.COMPLETE) ?
+            this.phases.COMPLETE : this.phases.INITIAL;
+
+        /** The test status code.*/
+        this.status = this.NOTRUN;
+        this.timeout_id = null;
+        this.index = null;
+
+        this.properties = properties || {};
+        this.timeout_length = settings.test_timeout;
+        if (this.timeout_length !== null) {
+            this.timeout_length *= tests.timeout_multiplier;
+        }
+
+        /** A message indicating the reason for test failure. */
+        this.message = null;
+        /** Stack trace in case of failure. */
+        this.stack = null;
+
+        this.steps = [];
+        this._is_promise_test = false;
+
+        this.cleanup_callbacks = [];
+        this._user_defined_cleanup_count = 0;
+        this._done_callbacks = [];
+
+        if (typeof AbortController === "function") {
+            this._abortController = new AbortController();
+        }
+
+        // Tests declared following harness completion are likely an indication
+        // of a programming error, but they cannot be reported
+        // deterministically.
+        if (tests.phase === tests.phases.COMPLETE) {
+            return;
+        }
+
+        tests.push(this);
+    }
+
+    /**
+     * Enum of possible test statuses.
+     *
+     * :values:
+     *   - ``PASS``
+     *   - ``FAIL``
+     *   - ``TIMEOUT``
+     *   - ``NOTRUN``
+     *   - ``PRECONDITION_FAILED``
+     */
+    Test.statuses = {
+        PASS:0,
+        FAIL:1,
+        TIMEOUT:2,
+        NOTRUN:3,
+        PRECONDITION_FAILED:4
+    };
+
+    Test.prototype = merge({}, Test.statuses);
+
+    Test.prototype.phases = {
+        INITIAL:0,
+        STARTED:1,
+        HAS_RESULT:2,
+        CLEANING:3,
+        COMPLETE:4
+    };
+
+    Test.prototype.status_formats = {
+        0: "Pass",
+        1: "Fail",
+        2: "Timeout",
+        3: "Not Run",
+        4: "Optional Feature Unsupported",
+    }
+
+    Test.prototype.format_status = function() {
+        return this.status_formats[this.status];
+    }
+
+    Test.prototype.structured_clone = function()
+    {
+        if (!this._structured_clone) {
+            var msg = this.message;
+            msg = msg ? String(msg) : msg;
+            this._structured_clone = merge({
+                name:String(this.name),
+                properties:merge({}, this.properties),
+                phases:merge({}, this.phases)
+            }, Test.statuses);
+        }
+        this._structured_clone.status = this.status;
+        this._structured_clone.message = this.message;
+        this._structured_clone.stack = this.stack;
+        this._structured_clone.index = this.index;
+        this._structured_clone.phase = this.phase;
+        return this._structured_clone;
+    };
+
+    /**
+     * Run a single step of an ongoing test.
+     *
+     * @param {string} func - Callback function to run as a step. If
+     * this throws an :js:func:`AssertionError`, or any other
+     * exception, the :js:class:`Test` status is set to ``FAIL``.
+     * @param {Object} [this_obj] - The object to use as the this
+     * value when calling ``func``. Defaults to the  :js:class:`Test` object.
+     */
+    Test.prototype.step = function(func, this_obj)
+    {
+        if (this.phase > this.phases.STARTED) {
+            return;
+        }
+
+        if (settings.debug && this.phase !== this.phases.STARTED) {
+            console.log("TEST START", this.name);
+        }
+        this.phase = this.phases.STARTED;
+        //If we don't get a result before the harness times out that will be a test timeout
+        this.set_status(this.TIMEOUT, "Test timed out");
+
+        tests.started = true;
+        tests.current_test = this;
+        tests.notify_test_state(this);
+
+        if (this.timeout_id === null) {
+            this.set_timeout();
+        }
+
+        this.steps.push(func);
+
+        if (arguments.length === 1) {
+            this_obj = this;
+        }
+
+        if (settings.debug) {
+            console.debug("TEST STEP", this.name);
+        }
+
+        try {
+            return func.apply(this_obj, Array.prototype.slice.call(arguments, 2));
+        } catch (e) {
+            if (this.phase >= this.phases.HAS_RESULT) {
+                return;
+            }
+            var status = e instanceof OptionalFeatureUnsupportedError ? this.PRECONDITION_FAILED : this.FAIL;
+            var message = String((typeof e === "object" && e !== null) ? e.message : e);
+            var stack = e.stack ? e.stack : null;
+
+            this.set_status(status, message, stack);
+            this.phase = this.phases.HAS_RESULT;
+            this.done();
+        } finally {
+            this.current_test = null;
+        }
+    };
+
+    /**
+     * Wrap a function so that it runs as a step of the current test.
+     *
+     * This allows creating a callback function that will run as a
+     * test step.
+     *
+     * @example
+     * let t = async_test("Example");
+     * onload = t.step_func(e => {
+     *   assert_equals(e.name, "load");
+     *   // Mark the test as complete.
+     *   t.done();
+     * })
+     *
+     * @param {string} func - Function to run as a step. If this
+     * throws an :js:func:`AssertionError`, or any other exception,
+     * the :js:class:`Test` status is set to ``FAIL``.
+     * @param {Object} [this_obj] - The object to use as the this
+     * value when calling ``func``. Defaults to the :js:class:`Test` object.
+     */
+    Test.prototype.step_func = function(func, this_obj)
+    {
+        var test_this = this;
+
+        if (arguments.length === 1) {
+            this_obj = test_this;
+        }
+
+        return function()
+        {
+            return test_this.step.apply(test_this, [func, this_obj].concat(
+                Array.prototype.slice.call(arguments)));
+        };
+    };
+
+    /**
+     * Wrap a function so that it runs as a step of the current test,
+     * and automatically marks the test as complete if the function
+     * returns without error.
+     *
+     * @param {string} func - Function to run as a step. If this
+     * throws an :js:func:`AssertionError`, or any other exception,
+     * the :js:class:`Test` status is set to ``FAIL``. If it returns
+     * without error the status is set to ``PASS``.
+     * @param {Object} [this_obj] - The object to use as the this
+     * value when calling `func`. Defaults to the :js:class:`Test` object.
+     */
+    Test.prototype.step_func_done = function(func, this_obj)
+    {
+        var test_this = this;
+
+        if (arguments.length === 1) {
+            this_obj = test_this;
+        }
+
+        return function()
+        {
+            if (func) {
+                test_this.step.apply(test_this, [func, this_obj].concat(
+                    Array.prototype.slice.call(arguments)));
+            }
+            test_this.done();
+        };
+    };
+
+    /**
+     * Return a function that automatically sets the current test to
+     * ``FAIL`` if it's called.
+     *
+     * @param {string} [description] - Error message to add to assert
+     * in case of failure.
+     *
+     */
+    Test.prototype.unreached_func = function(description)
+    {
+        return this.step_func(function() {
+            assert_unreached(description);
+        });
+    };
+
+    /**
+     * Run a function as a step of the test after a given timeout.
+     *
+     * This multiplies the timeout by the global timeout multiplier to
+     * account for the expected execution speed of the current test
+     * environment. For example ``test.step_timeout(f, 2000)`` with a
+     * timeout multiplier of 2 will wait for 4000ms before calling ``f``.
+     *
+     * In general it's encouraged to use :js:func:`Test.step_wait` or
+     * :js:func:`step_wait_func` in preference to this function where possible,
+     * as they provide better test performance.
+     *
+     * @param {Function} func - Function to run as a test
+     * step.
+     * @param {number} timeout - Time in ms to wait before running the
+     * test step. The actual wait time is ``timeout`` x
+     * ``timeout_multiplier``.
+     *
+     */
+    Test.prototype.step_timeout = function(func, timeout) {
+        var test_this = this;
+        var args = Array.prototype.slice.call(arguments, 2);
+        return setTimeout(this.step_func(function() {
+            return func.apply(test_this, args);
+        }), timeout * tests.timeout_multiplier);
+    };
+
+    /**
+     * Poll for a function to return true, and call a callback
+     * function once it does, or assert if a timeout is
+     * reached. This is preferred over a simple step_timeout
+     * whenever possible since it allows the timeout to be longer
+     * to reduce intermittents without compromising test execution
+     * speed when the condition is quickly met.
+     *
+     * @param {Function} cond A function taking no arguments and
+     *                        returning a boolean. The callback is called
+     *                        when this function returns true.
+     * @param {Function} func A function taking no arguments to call once
+     *                        the condition is met.
+     * @param {string} [description] Error message to add to assert in case of
+     *                               failure.
+     * @param {number} timeout Timeout in ms. This is multiplied by the global
+     *                         timeout_multiplier
+     * @param {number} interval Polling interval in ms
+     *
+     */
+    Test.prototype.step_wait_func = function(cond, func, description,
+                                             timeout=3000, interval=100) {
+        var timeout_full = timeout * tests.timeout_multiplier;
+        var remaining = Math.ceil(timeout_full / interval);
+        var test_this = this;
+
+        var wait_for_inner = test_this.step_func(() => {
+            if (cond()) {
+                func();
+            } else {
+                if(remaining === 0) {
+                    assert(false, "step_wait_func", description,
+                           "Timed out waiting on condition");
+                }
+                remaining--;
+                setTimeout(wait_for_inner, interval);
+            }
+        });
+
+        wait_for_inner();
+    };
+
+    /**
+     * Poll for a function to return true, and invoke a callback
+     * followed by this.done() once it does, or assert if a timeout
+     * is reached. This is preferred over a simple step_timeout
+     * whenever possible since it allows the timeout to be longer
+     * to reduce intermittents without compromising test execution speed
+     * when the condition is quickly met.
+     *
+     * @example
+     * async_test(t => {
+     *  const popup = window.open("resources/coop-coep.py?coop=same-origin&coep=&navigate=about:blank");
+     *  t.add_cleanup(() => popup.close());
+     *  assert_equals(window, popup.opener);
+     *
+     *  popup.onload = t.step_func(() => {
+     *    assert_true(popup.location.href.endsWith("&navigate=about:blank"));
+     *    // Use step_wait_func_done as about:blank cannot message back.
+     *    t.step_wait_func_done(() => popup.location.href === "about:blank");
+     *  });
+     * }, "Navigating a popup to about:blank");
+     *
+     * @param {Function} cond A function taking no arguments and
+     *                        returning a boolean. The callback is called
+     *                        when this function returns true.
+     * @param {Function} func A function taking no arguments to call once
+     *                        the condition is met.
+     * @param {string} [description] Error message to add to assert in case of
+     *                               failure.
+     * @param {number} timeout Timeout in ms. This is multiplied by the global
+     *                         timeout_multiplier
+     * @param {number} interval Polling interval in ms
+     *
+     */
+    Test.prototype.step_wait_func_done = function(cond, func, description,
+                                                  timeout=3000, interval=100) {
+         this.step_wait_func(cond, () => {
+            if (func) {
+                func();
+            }
+            this.done();
+         }, description, timeout, interval);
+    };
+
+    /**
+     * Poll for a function to return true, and resolve a promise
+     * once it does, or assert if a timeout is reached. This is
+     * preferred over a simple step_timeout whenever possible
+     * since it allows the timeout to be longer to reduce
+     * intermittents without compromising test execution speed
+     * when the condition is quickly met.
+     *
+     * @example
+     * promise_test(async t => {
+     *  // …
+     * await t.step_wait(() => frame.contentDocument === null, "Frame navigated to a cross-origin document");
+     * // …
+     * }, "");
+     *
+     * @param {Function} cond A function taking no arguments and
+     *                        returning a boolean.
+     * @param {string} [description] Error message to add to assert in case of
+     *                              failure.
+     * @param {number} timeout Timeout in ms. This is multiplied by the global
+     *                         timeout_multiplier
+     * @param {number} interval Polling interval in ms
+     * @returns {Promise} Promise resolved once cond is met.
+     *
+     */
+    Test.prototype.step_wait = function(cond, description, timeout=3000, interval=100) {
+        return new Promise(resolve => {
+            this.step_wait_func(cond, resolve, description, timeout, interval);
+        });
+    }
+
+    /*
+     * Private method for registering cleanup functions. `testharness.js`
+     * internals should use this method instead of the public `add_cleanup`
+     * method in order to hide implementation details from the harness status
+     * message in the case errors.
+     */
+    Test.prototype._add_cleanup = function(callback) {
+        this.cleanup_callbacks.push(callback);
+    };
+
+    /**
+     * Schedule a function to be run after the test result is known, regardless
+     * of passing or failing state.
+     *
+     * The behavior of this function will not
+     * influence the result of the test, but if an exception is thrown, the
+     * test harness will report an error.
+     *
+     * @param {Function} callback - The cleanup function to run. This
+     * is called with no arguments.
+     */
+    Test.prototype.add_cleanup = function(callback) {
+        this._user_defined_cleanup_count += 1;
+        this._add_cleanup(callback);
+    };
+
+    Test.prototype.set_timeout = function()
+    {
+        if (this.timeout_length !== null) {
+            var this_obj = this;
+            this.timeout_id = setTimeout(function()
+                                         {
+                                             this_obj.timeout();
+                                         }, this.timeout_length);
+        }
+    };
+
+    Test.prototype.set_status = function(status, message, stack)
+    {
+        this.status = status;
+        this.message = message;
+        this.stack = stack ? stack : null;
+    };
+
+    /**
+     * Manually set the test status to ``TIMEOUT``.
+     */
+    Test.prototype.timeout = function()
+    {
+        this.timeout_id = null;
+        this.set_status(this.TIMEOUT, "Test timed out");
+        this.phase = this.phases.HAS_RESULT;
+        this.done();
+    };
+
+    /**
+     * Manually set the test status to ``TIMEOUT``.
+     *
+     * Alias for `Test.timeout <#Test.timeout>`_.
+     */
+    Test.prototype.force_timeout = function() {
+        return this.timeout();
+    };
+
+    /**
+     * Mark the test as complete.
+     *
+     * This sets the test status to ``PASS`` if no other status was
+     * already recorded. Any subsequent attempts to run additional
+     * test steps will be ignored.
+     *
+     * After setting the test status any test cleanup functions will
+     * be run.
+     */
+    Test.prototype.done = function()
+    {
+        if (this.phase >= this.phases.CLEANING) {
+            return;
+        }
+
+        if (this.phase <= this.phases.STARTED) {
+            this.set_status(this.PASS, null);
+        }
+
+        if (global_scope.clearTimeout) {
+            clearTimeout(this.timeout_id);
+        }
+
+        if (settings.debug) {
+            console.log("TEST DONE",
+                        this.status,
+                        this.name);
+        }
+
+        this.cleanup();
+    };
+
+    function add_test_done_callback(test, callback)
+    {
+        if (test.phase === test.phases.COMPLETE) {
+            callback();
+            return;
+        }
+
+        test._done_callbacks.push(callback);
+    }
+
+    /*
+     * Invoke all specified cleanup functions. If one or more produce an error,
+     * the context is in an unpredictable state, so all further testing should
+     * be cancelled.
+     */
+    Test.prototype.cleanup = function() {
+        var errors = [];
+        var bad_value_count = 0;
+        function on_error(e) {
+            errors.push(e);
+            // Abort tests immediately so that tests declared within subsequent
+            // cleanup functions are not run.
+            tests.abort();
+        }
+        var this_obj = this;
+        var results = [];
+
+        this.phase = this.phases.CLEANING;
+
+        if (this._abortController) {
+            this._abortController.abort("Test cleanup");
+        }
+
+        forEach(this.cleanup_callbacks,
+                function(cleanup_callback) {
+                    var result;
+
+                    try {
+                        result = cleanup_callback();
+                    } catch (e) {
+                        on_error(e);
+                        return;
+                    }
+
+                    if (!is_valid_cleanup_result(this_obj, result)) {
+                        bad_value_count += 1;
+                        // Abort tests immediately so that tests declared
+                        // within subsequent cleanup functions are not run.
+                        tests.abort();
+                    }
+
+                    results.push(result);
+                });
+
+        if (!this._is_promise_test) {
+            cleanup_done(this_obj, errors, bad_value_count);
+        } else {
+            all_async(results,
+                      function(result, done) {
+                          if (result && typeof result.then === "function") {
+                              result
+                                  .then(null, on_error)
+                                  .then(done);
+                          } else {
+                              done();
+                          }
+                      },
+                      function() {
+                          cleanup_done(this_obj, errors, bad_value_count);
+                      });
+        }
+    };
+
+    /*
+     * Determine if the return value of a cleanup function is valid for a given
+     * test. Any test may return the value `undefined`. Tests created with
+     * `promise_test` may alternatively return "thenable" object values.
+     */
+    function is_valid_cleanup_result(test, result) {
+        if (result === undefined) {
+            return true;
+        }
+
+        if (test._is_promise_test) {
+            return result && typeof result.then === "function";
+        }
+
+        return false;
+    }
+
+    function cleanup_done(test, errors, bad_value_count) {
+        if (errors.length || bad_value_count) {
+            var total = test._user_defined_cleanup_count;
+
+            tests.status.status = tests.status.ERROR;
+            tests.status.stack = null;
+            tests.status.message = "Test named '" + test.name +
+                "' specified " + total +
+                " 'cleanup' function" + (total > 1 ? "s" : "");
+
+            if (errors.length) {
+                tests.status.message += ", and " + errors.length + " failed";
+                tests.status.stack = ((typeof errors[0] === "object" &&
+                                       errors[0].hasOwnProperty("stack")) ?
+                                      errors[0].stack : null);
+            }
+
+            if (bad_value_count) {
+                var type = test._is_promise_test ?
+                   "non-thenable" : "non-undefined";
+                tests.status.message += ", and " + bad_value_count +
+                    " returned a " + type + " value";
+            }
+
+            tests.status.message += ".";
+        }
+
+        test.phase = test.phases.COMPLETE;
+        tests.result(test);
+        forEach(test._done_callbacks,
+                function(callback) {
+                    callback();
+                });
+        test._done_callbacks.length = 0;
+    }
+
+    /**
+     * Gives an AbortSignal that will be aborted when the test finishes.
+     */
+    Test.prototype.get_signal = function() {
+        if (!this._abortController) {
+            throw new Error("AbortController is not supported in this browser");
+        }
+        return this._abortController.signal;
+    }
+
+    /**
+     * A RemoteTest object mirrors a Test object on a remote worker. The
+     * associated RemoteWorker updates the RemoteTest object in response to
+     * received events. In turn, the RemoteTest object replicates these events
+     * on the local document. This allows listeners (test result reporting
+     * etc..) to transparently handle local and remote events.
+     */
+    function RemoteTest(clone) {
+        var this_obj = this;
+        Object.keys(clone).forEach(
+                function(key) {
+                    this_obj[key] = clone[key];
+                });
+        this.index = null;
+        this.phase = this.phases.INITIAL;
+        this.update_state_from(clone);
+        this._done_callbacks = [];
+        tests.push(this);
+    }
+
+    RemoteTest.prototype.structured_clone = function() {
+        var clone = {};
+        Object.keys(this).forEach(
+                (function(key) {
+                    var value = this[key];
+                    // `RemoteTest` instances are responsible for managing
+                    // their own "done" callback functions, so those functions
+                    // are not relevant in other execution contexts. Because of
+                    // this (and because Function values cannot be serialized
+                    // for cross-realm transmittance), the property should not
+                    // be considered when cloning instances.
+                    if (key === '_done_callbacks' ) {
+                        return;
+                    }
+
+                    if (typeof value === "object" && value !== null) {
+                        clone[key] = merge({}, value);
+                    } else {
+                        clone[key] = value;
+                    }
+                }).bind(this));
+        clone.phases = merge({}, this.phases);
+        return clone;
+    };
+
+    /**
+     * `RemoteTest` instances are objects which represent tests running in
+     * another realm. They do not define "cleanup" functions (if necessary,
+     * such functions are defined on the associated `Test` instance within the
+     * external realm). However, `RemoteTests` may have "done" callbacks (e.g.
+     * as attached by the `Tests` instance responsible for tracking the overall
+     * test status in the parent realm). The `cleanup` method delegates to
+     * `done` in order to ensure that such callbacks are invoked following the
+     * completion of the `RemoteTest`.
+     */
+    RemoteTest.prototype.cleanup = function() {
+        this.done();
+    };
+    RemoteTest.prototype.phases = Test.prototype.phases;
+    RemoteTest.prototype.update_state_from = function(clone) {
+        this.status = clone.status;
+        this.message = clone.message;
+        this.stack = clone.stack;
+        if (this.phase === this.phases.INITIAL) {
+            this.phase = this.phases.STARTED;
+        }
+    };
+    RemoteTest.prototype.done = function() {
+        this.phase = this.phases.COMPLETE;
+
+        forEach(this._done_callbacks,
+                function(callback) {
+                    callback();
+                });
+    }
+
+    RemoteTest.prototype.format_status = function() {
+        return Test.prototype.status_formats[this.status];
+    }
+
+    /*
+     * A RemoteContext listens for test events from a remote test context, such
+     * as another window or a worker. These events are then used to construct
+     * and maintain RemoteTest objects that mirror the tests running in the
+     * remote context.
+     *
+     * An optional third parameter can be used as a predicate to filter incoming
+     * MessageEvents.
+     */
+    function RemoteContext(remote, message_target, message_filter) {
+        this.running = true;
+        this.started = false;
+        this.tests = new Array();
+        this.early_exception = null;
+
+        var this_obj = this;
+        // If remote context is cross origin assigning to onerror is not
+        // possible, so silently catch those errors.
+        try {
+          remote.onerror = function(error) { this_obj.remote_error(error); };
+        } catch (e) {
+          // Ignore.
+        }
+
+        // Keeping a reference to the remote object and the message handler until
+        // remote_done() is seen prevents the remote object and its message channel
+        // from going away before all the messages are dispatched.
+        this.remote = remote;
+        this.message_target = message_target;
+        this.message_handler = function(message) {
+            var passesFilter = !message_filter || message_filter(message);
+            // The reference to the `running` property in the following
+            // condition is unnecessary because that value is only set to
+            // `false` after the `message_handler` function has been
+            // unsubscribed.
+            // TODO: Simplify the condition by removing the reference.
+            if (this_obj.running && message.data && passesFilter &&
+                (message.data.type in this_obj.message_handlers)) {
+                this_obj.message_handlers[message.data.type].call(this_obj, message.data);
+            }
+        };
+
+        if (self.Promise) {
+            this.done = new Promise(function(resolve) {
+                this_obj.doneResolve = resolve;
+            });
+        }
+
+        this.message_target.addEventListener("message", this.message_handler);
+    }
+
+    RemoteContext.prototype.remote_error = function(error) {
+        if (error.preventDefault) {
+            error.preventDefault();
+        }
+
+        // Defer interpretation of errors until the testing protocol has
+        // started and the remote test's `allow_uncaught_exception` property
+        // is available.
+        if (!this.started) {
+            this.early_exception = error;
+        } else if (!this.allow_uncaught_exception) {
+            this.report_uncaught(error);
+        }
+    };
+
+    RemoteContext.prototype.report_uncaught = function(error) {
+        var message = error.message || String(error);
+        var filename = (error.filename ? " " + error.filename: "");
+        // FIXME: Display remote error states separately from main document
+        // error state.
+        tests.set_status(tests.status.ERROR,
+                         "Error in remote" + filename + ": " + message,
+                         error.stack);
+    };
+
+    RemoteContext.prototype.start = function(data) {
+        this.started = true;
+        this.allow_uncaught_exception = data.properties.allow_uncaught_exception;
+
+        if (this.early_exception && !this.allow_uncaught_exception) {
+            this.report_uncaught(this.early_exception);
+        }
+    };
+
+    RemoteContext.prototype.test_state = function(data) {
+        var remote_test = this.tests[data.test.index];
+        if (!remote_test) {
+            remote_test = new RemoteTest(data.test);
+            this.tests[data.test.index] = remote_test;
+        }
+        remote_test.update_state_from(data.test);
+        tests.notify_test_state(remote_test);
+    };
+
+    RemoteContext.prototype.test_done = function(data) {
+        var remote_test = this.tests[data.test.index];
+        remote_test.update_state_from(data.test);
+        remote_test.done();
+        tests.result(remote_test);
+    };
+
+    RemoteContext.prototype.remote_done = function(data) {
+        if (tests.status.status === null &&
+            data.status.status !== data.status.OK) {
+            tests.set_status(data.status.status, data.status.message, data.status.stack);
+        }
+
+        for (let assert of data.asserts) {
+            var record = new AssertRecord();
+            record.assert_name = assert.assert_name;
+            record.args = assert.args;
+            record.test = assert.test != null ? this.tests[assert.test.index] : null;
+            record.status = assert.status;
+            record.stack = assert.stack;
+            tests.asserts_run.push(record);
+        }
+
+        this.message_target.removeEventListener("message", this.message_handler);
+        this.running = false;
+
+        // If remote context is cross origin assigning to onerror is not
+        // possible, so silently catch those errors.
+        try {
+          this.remote.onerror = null;
+        } catch (e) {
+          // Ignore.
+        }
+
+        this.remote = null;
+        this.message_target = null;
+        if (this.doneResolve) {
+            this.doneResolve();
+        }
+
+        if (tests.all_done()) {
+            tests.complete();
+        }
+    };
+
+    RemoteContext.prototype.message_handlers = {
+        start: RemoteContext.prototype.start,
+        test_state: RemoteContext.prototype.test_state,
+        result: RemoteContext.prototype.test_done,
+        complete: RemoteContext.prototype.remote_done
+    };
+
+    /**
+     * @class
+     * Status of the overall harness
+     */
+    function TestsStatus()
+    {
+        /** The status code */
+        this.status = null;
+        /** Message in case of failure */
+        this.message = null;
+        /** Stack trace in case of an exception. */
+        this.stack = null;
+    }
+
+    /**
+     * Enum of possible harness statuses.
+     *
+     * :values:
+     *   - ``OK``
+     *   - ``ERROR``
+     *   - ``TIMEOUT``
+     *   - ``PRECONDITION_FAILED``
+     */
+    TestsStatus.statuses = {
+        OK:0,
+        ERROR:1,
+        TIMEOUT:2,
+        PRECONDITION_FAILED:3
+    };
+
+    TestsStatus.prototype = merge({}, TestsStatus.statuses);
+
+    TestsStatus.prototype.formats = {
+        0: "OK",
+        1: "Error",
+        2: "Timeout",
+        3: "Optional Feature Unsupported"
+    };
+
+    TestsStatus.prototype.structured_clone = function()
+    {
+        if (!this._structured_clone) {
+            var msg = this.message;
+            msg = msg ? String(msg) : msg;
+            this._structured_clone = merge({
+                status:this.status,
+                message:msg,
+                stack:this.stack
+            }, TestsStatus.statuses);
+        }
+        return this._structured_clone;
+    };
+
+    TestsStatus.prototype.format_status = function() {
+        return this.formats[this.status];
+    };
+
+    /**
+     * @class
+     * Record of an assert that ran.
+     *
+     * @param {Test} test - The test which ran the assert.
+     * @param {string} assert_name - The function name of the assert.
+     * @param {Any} args - The arguments passed to the assert function.
+     */
+    function AssertRecord(test, assert_name, args = []) {
+        /** Name of the assert that ran */
+        this.assert_name = assert_name;
+        /** Test that ran the assert */
+        this.test = test;
+        // Avoid keeping complex objects alive
+        /** Stringification of the arguments that were passed to the assert function */
+        this.args = args.map(x => format_value(x).replace(/\n/g, " "));
+        /** Status of the assert */
+        this.status = null;
+    }
+
+    AssertRecord.prototype.structured_clone = function() {
+        return {
+            assert_name: this.assert_name,
+            test: this.test ? this.test.structured_clone() : null,
+            args: this.args,
+            status: this.status,
+        };
+    };
+
+    function Tests()
+    {
+        this.tests = [];
+        this.num_pending = 0;
+
+        this.phases = {
+            INITIAL:0,
+            SETUP:1,
+            HAVE_TESTS:2,
+            HAVE_RESULTS:3,
+            COMPLETE:4
+        };
+        this.phase = this.phases.INITIAL;
+
+        this.properties = {};
+
+        this.wait_for_finish = false;
+        this.processing_callbacks = false;
+
+        this.allow_uncaught_exception = false;
+
+        this.file_is_test = false;
+        // This value is lazily initialized in order to avoid introducing a
+        // dependency on ECMAScript 2015 Promises to all tests.
+        this.promise_tests = null;
+        this.promise_setup_called = false;
+
+        this.timeout_multiplier = 1;
+        this.timeout_length = test_environment.test_timeout();
+        this.timeout_id = null;
+
+        this.start_callbacks = [];
+        this.test_state_callbacks = [];
+        this.test_done_callbacks = [];
+        this.all_done_callbacks = [];
+
+        this.hide_test_state = false;
+        this.pending_remotes = [];
+
+        this.current_test = null;
+        this.asserts_run = [];
+
+        // Track whether output is enabled, and thus whether or not we should
+        // track asserts.
+        //
+        // On workers we don't get properties set from testharnessreport.js, so
+        // we don't know whether or not to track asserts. To avoid the
+        // resulting performance hit, we assume we are not meant to. This means
+        // that assert tracking does not function on workers.
+        this.output = settings.output && 'document' in global_scope;
+
+        this.status = new TestsStatus();
+
+        var this_obj = this;
+
+        test_environment.add_on_loaded_callback(function() {
+            if (this_obj.all_done()) {
+                this_obj.complete();
+            }
+        });
+
+        this.set_timeout();
+    }
+
+    Tests.prototype.setup = function(func, properties)
+    {
+        if (this.phase >= this.phases.HAVE_RESULTS) {
+            return;
+        }
+
+        if (this.phase < this.phases.SETUP) {
+            this.phase = this.phases.SETUP;
+        }
+
+        this.properties = properties;
+
+        for (var p in properties) {
+            if (properties.hasOwnProperty(p)) {
+                var value = properties[p];
+                if (p == "allow_uncaught_exception") {
+                    this.allow_uncaught_exception = value;
+                } else if (p == "explicit_done" && value) {
+                    this.wait_for_finish = true;
+                } else if (p == "explicit_timeout" && value) {
+                    this.timeout_length = null;
+                    if (this.timeout_id)
+                    {
+                        clearTimeout(this.timeout_id);
+                    }
+                } else if (p == "single_test" && value) {
+                    this.set_file_is_test();
+                } else if (p == "timeout_multiplier") {
+                    this.timeout_multiplier = value;
+                    if (this.timeout_length) {
+                         this.timeout_length *= this.timeout_multiplier;
+                    }
+                } else if (p == "hide_test_state") {
+                    this.hide_test_state = value;
+                } else if (p == "output") {
+                    this.output = value;
+                } else if (p === "debug") {
+                    settings.debug = value;
+                }
+            }
+        }
+
+        if (func) {
+            try {
+                func();
+            } catch (e) {
+                this.status.status = e instanceof OptionalFeatureUnsupportedError ? this.status.PRECONDITION_FAILED : this.status.ERROR;
+                this.status.message = String(e);
+                this.status.stack = e.stack ? e.stack : null;
+                this.complete();
+            }
+        }
+        this.set_timeout();
+    };
+
+    Tests.prototype.set_file_is_test = function() {
+        if (this.tests.length > 0) {
+            throw new Error("Tried to set file as test after creating a test");
+        }
+        this.wait_for_finish = true;
+        this.file_is_test = true;
+        // Create the test, which will add it to the list of tests
+        tests.current_test = async_test();
+    };
+
+    Tests.prototype.set_status = function(status, message, stack)
+    {
+        this.status.status = status;
+        this.status.message = message;
+        this.status.stack = stack ? stack : null;
+    };
+
+    Tests.prototype.set_timeout = function() {
+        if (global_scope.clearTimeout) {
+            var this_obj = this;
+            clearTimeout(this.timeout_id);
+            if (this.timeout_length !== null) {
+                this.timeout_id = setTimeout(function() {
+                                                 this_obj.timeout();
+                                             }, this.timeout_length);
+            }
+        }
+    };
+
+    Tests.prototype.timeout = function() {
+        var test_in_cleanup = null;
+
+        if (this.status.status === null) {
+            forEach(this.tests,
+                    function(test) {
+                        // No more than one test is expected to be in the
+                        // "CLEANUP" phase at any time
+                        if (test.phase === test.phases.CLEANING) {
+                            test_in_cleanup = test;
+                        }
+
+                        test.phase = test.phases.COMPLETE;
+                    });
+
+            // Timeouts that occur while a test is in the "cleanup" phase
+            // indicate that some global state was not properly reverted. This
+            // invalidates the overall test execution, so the timeout should be
+            // reported as an error and cancel the execution of any remaining
+            // tests.
+            if (test_in_cleanup) {
+                this.status.status = this.status.ERROR;
+                this.status.message = "Timeout while running cleanup for " +
+                    "test named \"" + test_in_cleanup.name + "\".";
+                tests.status.stack = null;
+            } else {
+                this.status.status = this.status.TIMEOUT;
+            }
+        }
+
+        this.complete();
+    };
+
+    Tests.prototype.end_wait = function()
+    {
+        this.wait_for_finish = false;
+        if (this.all_done()) {
+            this.complete();
+        }
+    };
+
+    Tests.prototype.push = function(test)
+    {
+        if (this.phase < this.phases.HAVE_TESTS) {
+            this.start();
+        }
+        this.num_pending++;
+        test.index = this.tests.push(test);
+        this.notify_test_state(test);
+    };
+
+    Tests.prototype.notify_test_state = function(test) {
+        var this_obj = this;
+        forEach(this.test_state_callbacks,
+                function(callback) {
+                    callback(test, this_obj);
+                });
+    };
+
+    Tests.prototype.all_done = function() {
+        return (this.tests.length > 0 || this.pending_remotes.length > 0) &&
+                test_environment.all_loaded &&
+                (this.num_pending === 0 || this.is_aborted) && !this.wait_for_finish &&
+                !this.processing_callbacks &&
+                !this.pending_remotes.some(function(w) { return w.running; });
+    };
+
+    Tests.prototype.start = function() {
+        this.phase = this.phases.HAVE_TESTS;
+        this.notify_start();
+    };
+
+    Tests.prototype.notify_start = function() {
+        var this_obj = this;
+        forEach (this.start_callbacks,
+                 function(callback)
+                 {
+                     callback(this_obj.properties);
+                 });
+    };
+
+    Tests.prototype.result = function(test)
+    {
+        // If the harness has already transitioned beyond the `HAVE_RESULTS`
+        // phase, subsequent tests should not cause it to revert.
+        if (this.phase <= this.phases.HAVE_RESULTS) {
+            this.phase = this.phases.HAVE_RESULTS;
+        }
+        this.num_pending--;
+        this.notify_result(test);
+    };
+
+    Tests.prototype.notify_result = function(test) {
+        var this_obj = this;
+        this.processing_callbacks = true;
+        forEach(this.test_done_callbacks,
+                function(callback)
+                {
+                    callback(test, this_obj);
+                });
+        this.processing_callbacks = false;
+        if (this_obj.all_done()) {
+            this_obj.complete();
+        }
+    };
+
+    Tests.prototype.complete = function() {
+        if (this.phase === this.phases.COMPLETE) {
+            return;
+        }
+        var this_obj = this;
+        var all_complete = function() {
+            this_obj.phase = this_obj.phases.COMPLETE;
+            this_obj.notify_complete();
+        };
+        var incomplete = filter(this.tests,
+                                function(test) {
+                                    return test.phase < test.phases.COMPLETE;
+                                });
+
+        /**
+         * To preserve legacy behavior, overall test completion must be
+         * signaled synchronously.
+         */
+        if (incomplete.length === 0) {
+            all_complete();
+            return;
+        }
+
+        all_async(incomplete,
+                  function(test, testDone)
+                  {
+                      if (test.phase === test.phases.INITIAL) {
+                          test.phase = test.phases.COMPLETE;
+                          testDone();
+                      } else {
+                          add_test_done_callback(test, testDone);
+                          test.cleanup();
+                      }
+                  },
+                  all_complete);
+    };
+
+    Tests.prototype.set_assert = function(assert_name, args) {
+        this.asserts_run.push(new AssertRecord(this.current_test, assert_name, args))
+    }
+
+    Tests.prototype.set_assert_status = function(index, status, stack) {
+        let assert_record = this.asserts_run[index];
+        assert_record.status = status;
+        assert_record.stack = stack;
+    }
+
+    /**
+     * Update the harness status to reflect an unrecoverable harness error that
+     * should cancel all further testing. Update all previously-defined tests
+     * which have not yet started to indicate that they will not be executed.
+     */
+    Tests.prototype.abort = function() {
+        this.status.status = this.status.ERROR;
+        this.is_aborted = true;
+
+        forEach(this.tests,
+                function(test) {
+                    if (test.phase === test.phases.INITIAL) {
+                        test.phase = test.phases.COMPLETE;
+                    }
+                });
+    };
+
+    /*
+     * Determine if any tests share the same `name` property. Return an array
+     * containing the names of any such duplicates.
+     */
+    Tests.prototype.find_duplicates = function() {
+        var names = Object.create(null);
+        var duplicates = [];
+
+        forEach (this.tests,
+                 function(test)
+                 {
+                     if (test.name in names && duplicates.indexOf(test.name) === -1) {
+                        duplicates.push(test.name);
+                     }
+                     names[test.name] = true;
+                 });
+
+        return duplicates;
+    };
+
+    function code_unit_str(char) {
+        return 'U+' + char.charCodeAt(0).toString(16);
+    }
+
+    function sanitize_unpaired_surrogates(str) {
+        return str.replace(
+            /([\ud800-\udbff]+)(?![\udc00-\udfff])|(^|[^\ud800-\udbff])([\udc00-\udfff]+)/g,
+            function(_, low, prefix, high) {
+                var output = prefix || "";  // prefix may be undefined
+                var string = low || high;  // only one of these alternates can match
+                for (var i = 0; i < string.length; i++) {
+                    output += code_unit_str(string[i]);
+                }
+                return output;
+            });
+    }
+
+    function sanitize_all_unpaired_surrogates(tests) {
+        forEach (tests,
+                 function (test)
+                 {
+                     var sanitized = sanitize_unpaired_surrogates(test.name);
+
+                     if (test.name !== sanitized) {
+                         test.name = sanitized;
+                         delete test._structured_clone;
+                     }
+                 });
+    }
+
+    Tests.prototype.notify_complete = function() {
+        var this_obj = this;
+        var duplicates;
+
+        if (this.status.status === null) {
+            duplicates = this.find_duplicates();
+
+            // Some transports adhere to UTF-8's restriction on unpaired
+            // surrogates. Sanitize the titles so that the results can be
+            // consistently sent via all transports.
+            sanitize_all_unpaired_surrogates(this.tests);
+
+            // Test names are presumed to be unique within test files--this
+            // allows consumers to use them for identification purposes.
+            // Duplicated names violate this expectation and should therefore
+            // be reported as an error.
+            if (duplicates.length) {
+                this.status.status = this.status.ERROR;
+                this.status.message =
+                   duplicates.length + ' duplicate test name' +
+                   (duplicates.length > 1 ? 's' : '') + ': "' +
+                   duplicates.join('", "') + '"';
+            } else {
+                this.status.status = this.status.OK;
+            }
+        }
+
+        forEach (this.all_done_callbacks,
+                 function(callback)
+                 {
+                     callback(this_obj.tests, this_obj.status, this_obj.asserts_run);
+                 });
+    };
+
+    /*
+     * Constructs a RemoteContext that tracks tests from a specific worker.
+     */
+    Tests.prototype.create_remote_worker = function(worker) {
+        var message_port;
+
+        if (is_service_worker(worker)) {
+            message_port = navigator.serviceWorker;
+            worker.postMessage({type: "connect"});
+        } else if (is_shared_worker(worker)) {
+            message_port = worker.port;
+            message_port.start();
+        } else {
+            message_port = worker;
+        }
+
+        return new RemoteContext(worker, message_port);
+    };
+
+    /*
+     * Constructs a RemoteContext that tracks tests from a specific window.
+     */
+    Tests.prototype.create_remote_window = function(remote) {
+        remote.postMessage({type: "getmessages"}, "*");
+        return new RemoteContext(
+            remote,
+            window,
+            function(msg) {
+                return msg.source === remote;
+            }
+        );
+    };
+
+    Tests.prototype.fetch_tests_from_worker = function(worker) {
+        if (this.phase >= this.phases.COMPLETE) {
+            return;
+        }
+
+        var remoteContext = this.create_remote_worker(worker);
+        this.pending_remotes.push(remoteContext);
+        return remoteContext.done;
+    };
+
+    /**
+     * Get test results from a worker and include them in the current test.
+     *
+     * @param {Worker|SharedWorker|ServiceWorker|MessagePort} port -
+     * Either a worker object or a port connected to a worker which is
+     * running tests..
+     * @returns {Promise} - A promise that's resolved once all the remote tests are complete.
+     */
+    function fetch_tests_from_worker(port) {
+        return tests.fetch_tests_from_worker(port);
+    }
+    expose(fetch_tests_from_worker, 'fetch_tests_from_worker');
+
+    Tests.prototype.fetch_tests_from_window = function(remote) {
+        if (this.phase >= this.phases.COMPLETE) {
+            return;
+        }
+
+        var remoteContext = this.create_remote_window(remote);
+        this.pending_remotes.push(remoteContext);
+        return remoteContext.done;
+    };
+
+    /**
+     * Aggregate tests from separate windows or iframes
+     * into the current document as if they were all part of the same test file.
+     *
+     * The document of the second window (or iframe) should include
+     * ``testharness.js``, but not ``testharnessreport.js``, and use
+     * :js:func:`test`, :js:func:`async_test`, and :js:func:`promise_test` in
+     * the usual manner.
+     *
+     * @param {Window} window - The window to fetch tests from.
+     */
+    function fetch_tests_from_window(window) {
+        return tests.fetch_tests_from_window(window);
+    }
+    expose(fetch_tests_from_window, 'fetch_tests_from_window');
+
+    /**
+     * Get test results from a shadow realm and include them in the current test.
+     *
+     * @param {ShadowRealm} realm - A shadow realm also running the test harness
+     * @returns {Promise} - A promise that's resolved once all the remote tests are complete.
+     */
+    function fetch_tests_from_shadow_realm(realm) {
+        var chan = new MessageChannel();
+        function receiveMessage(msg_json) {
+            chan.port1.postMessage(JSON.parse(msg_json));
+        }
+        var done = tests.fetch_tests_from_worker(chan.port2);
+        realm.evaluate("begin_shadow_realm_tests")(receiveMessage);
+        chan.port2.start();
+        return done;
+    }
+    expose(fetch_tests_from_shadow_realm, 'fetch_tests_from_shadow_realm');
+
+    /**
+     * Begin running tests in this shadow realm test harness.
+     *
+     * To be called after all tests have been loaded; it is an error to call
+     * this more than once or in a non-Shadow Realm environment
+     *
+     * @param {Function} postMessage - A function to send test updates to the
+     * incubating realm-- accepts JSON-encoded messages in the format used by
+     * RemoteContext
+     */
+    function begin_shadow_realm_tests(postMessage) {
+        if (!(test_environment instanceof ShadowRealmTestEnvironment)) {
+            throw new Error("begin_shadow_realm_tests called in non-Shadow Realm environment");
+        }
+
+        test_environment.begin(function (msg) {
+            postMessage(JSON.stringify(msg));
+        });
+    }
+    expose(begin_shadow_realm_tests, 'begin_shadow_realm_tests');
+
+    /**
+     * Timeout the tests.
+     *
+     * This only has an effect when ``explicit_timeout`` has been set
+     * in :js:func:`setup`. In other cases any call is a no-op.
+     *
+     */
+    function timeout() {
+        if (tests.timeout_length === null) {
+            tests.timeout();
+        }
+    }
+    expose(timeout, 'timeout');
+
+    /**
+     * Add a callback that's triggered when the first :js:class:`Test` is created.
+     *
+     * @param {Function} callback - Callback function. This is called
+     * without arguments.
+     */
+    function add_start_callback(callback) {
+        tests.start_callbacks.push(callback);
+    }
+
+    /**
+     * Add a callback that's triggered when a test state changes.
+     *
+     * @param {Function} callback - Callback function, called with the
+     * :js:class:`Test` as the only argument.
+     */
+    function add_test_state_callback(callback) {
+        tests.test_state_callbacks.push(callback);
+    }
+
+    /**
+     * Add a callback that's triggered when a test result is received.
+     *
+     * @param {Function} callback - Callback function, called with the
+     * :js:class:`Test` as the only argument.
+     */
+    function add_result_callback(callback) {
+        tests.test_done_callbacks.push(callback);
+    }
+
+    /**
+     * Add a callback that's triggered when all tests are complete.
+     *
+     * @param {Function} callback - Callback function, called with an
+     * array of :js:class:`Test` objects, a :js:class:`TestsStatus`
+     * object and an array of :js:class:`AssertRecord` objects. If the
+     * debug setting is ``false`` the final argument will be an empty
+     * array.
+     *
+     * For performance reasons asserts are only tracked when the debug
+     * setting is ``true``. In other cases the array of asserts will be
+     * empty.
+     */
+    function add_completion_callback(callback) {
+        tests.all_done_callbacks.push(callback);
+    }
+
+    expose(add_start_callback, 'add_start_callback');
+    expose(add_test_state_callback, 'add_test_state_callback');
+    expose(add_result_callback, 'add_result_callback');
+    expose(add_completion_callback, 'add_completion_callback');
+
+    function remove(array, item) {
+        var index = array.indexOf(item);
+        if (index > -1) {
+            array.splice(index, 1);
+        }
+    }
+
+    function remove_start_callback(callback) {
+        remove(tests.start_callbacks, callback);
+    }
+
+    function remove_test_state_callback(callback) {
+        remove(tests.test_state_callbacks, callback);
+    }
+
+    function remove_result_callback(callback) {
+        remove(tests.test_done_callbacks, callback);
+    }
+
+    function remove_completion_callback(callback) {
+       remove(tests.all_done_callbacks, callback);
+    }
+
+    /*
+     * Output listener
+    */
+
+    function Output() {
+        this.output_document = document;
+        this.output_node = null;
+        this.enabled = settings.output;
+        this.phase = this.INITIAL;
+    }
+
+    Output.prototype.INITIAL = 0;
+    Output.prototype.STARTED = 1;
+    Output.prototype.HAVE_RESULTS = 2;
+    Output.prototype.COMPLETE = 3;
+
+    Output.prototype.setup = function(properties) {
+        if (this.phase > this.INITIAL) {
+            return;
+        }
+
+        //If output is disabled in testharnessreport.js the test shouldn't be
+        //able to override that
+        this.enabled = this.enabled && (properties.hasOwnProperty("output") ?
+                                        properties.output : settings.output);
+    };
+
+    Output.prototype.init = function(properties) {
+        if (this.phase >= this.STARTED) {
+            return;
+        }
+        if (properties.output_document) {
+            this.output_document = properties.output_document;
+        } else {
+            this.output_document = document;
+        }
+        this.phase = this.STARTED;
+    };
+
+    Output.prototype.resolve_log = function() {
+        var output_document;
+        if (this.output_node) {
+            return;
+        }
+        if (typeof this.output_document === "function") {
+            output_document = this.output_document.apply(undefined);
+        } else {
+            output_document = this.output_document;
+        }
+        if (!output_document) {
+            return;
+        }
+        var node = output_document.getElementById("log");
+        if (!node) {
+            if (output_document.readyState === "loading") {
+                return;
+            }
+            node = output_document.createElementNS("http://www.w3.org/1999/xhtml", "div");
+            node.id = "log";
+            if (output_document.body) {
+                output_document.body.appendChild(node);
+            } else {
+                var root = output_document.documentElement;
+                var is_html = (root &&
+                               root.namespaceURI == "http://www.w3.org/1999/xhtml" &&
+                               root.localName == "html");
+                var is_svg = (output_document.defaultView &&
+                              "SVGSVGElement" in output_document.defaultView &&
+                              root instanceof output_document.defaultView.SVGSVGElement);
+                if (is_svg) {
+                    var foreignObject = output_document.createElementNS("http://www.w3.org/2000/svg", "foreignObject");
+                    foreignObject.setAttribute("width", "100%");
+                    foreignObject.setAttribute("height", "100%");
+                    root.appendChild(foreignObject);
+                    foreignObject.appendChild(node);
+                } else if (is_html) {
+                    root.appendChild(output_document.createElementNS("http://www.w3.org/1999/xhtml", "body"))
+                        .appendChild(node);
+                } else {
+                    root.appendChild(node);
+                }
+            }
+        }
+        this.output_document = output_document;
+        this.output_node = node;
+    };
+
+    Output.prototype.show_status = function() {
+        if (this.phase < this.STARTED) {
+            this.init({});
+        }
+        if (!this.enabled || this.phase === this.COMPLETE) {
+            return;
+        }
+        this.resolve_log();
+        if (this.phase < this.HAVE_RESULTS) {
+            this.phase = this.HAVE_RESULTS;
+        }
+        var done_count = tests.tests.length - tests.num_pending;
+        if (this.output_node && !tests.hide_test_state) {
+            if (done_count < 100 ||
+                (done_count < 1000 && done_count % 100 === 0) ||
+                done_count % 1000 === 0) {
+                this.output_node.textContent = "Running, " +
+                    done_count + " complete, " +
+                    tests.num_pending + " remain";
+            }
+        }
+    };
+
+    Output.prototype.show_results = function (tests, harness_status, asserts_run) {
+        if (this.phase >= this.COMPLETE) {
+            return;
+        }
+        if (!this.enabled) {
+            return;
+        }
+        if (!this.output_node) {
+            this.resolve_log();
+        }
+        this.phase = this.COMPLETE;
+
+        var log = this.output_node;
+        if (!log) {
+            return;
+        }
+        var output_document = this.output_document;
+
+        while (log.lastChild) {
+            log.removeChild(log.lastChild);
+        }
+
+        var stylesheet = output_document.createElementNS(xhtml_ns, "style");
+        stylesheet.textContent = stylesheetContent;
+        var heads = output_document.getElementsByTagName("head");
+        if (heads.length) {
+            heads[0].appendChild(stylesheet);
+        }
+
+        var status_number = {};
+        forEach(tests,
+                function(test) {
+                    var status = test.format_status();
+                    if (status_number.hasOwnProperty(status)) {
+                        status_number[status] += 1;
+                    } else {
+                        status_number[status] = 1;
+                    }
+                });
+
+        function status_class(status)
+        {
+            return status.replace(/\s/g, '').toLowerCase();
+        }
+
+        var summary_template = ["section", {"id":"summary"},
+                                ["h2", {}, "Summary"],
+                                function()
+                                {
+                                    var status = harness_status.format_status();
+                                    var rv = [["section", {},
+                                               ["p", {},
+                                                "Harness status: ",
+                                                ["span", {"class":status_class(status)},
+                                                 status
+                                                ],
+                                               ],
+                                               ["button",
+                                                {"onclick": "let evt = new Event('__test_restart'); " +
+                                                 "let canceled = !window.dispatchEvent(evt);" +
+                                                 "if (!canceled) { location.reload() }"},
+                                                "Rerun"]
+                                              ]];
+
+                                    if (harness_status.status === harness_status.ERROR) {
+                                        rv[0].push(["pre", {}, harness_status.message]);
+                                        if (harness_status.stack) {
+                                            rv[0].push(["pre", {}, harness_status.stack]);
+                                        }
+                                    }
+                                    return rv;
+                                },
+                                ["p", {}, "Found ${num_tests} tests"],
+                                function() {
+                                    var rv = [["div", {}]];
+                                    var i = 0;
+                                    while (Test.prototype.status_formats.hasOwnProperty(i)) {
+                                        if (status_number.hasOwnProperty(Test.prototype.status_formats[i])) {
+                                            var status = Test.prototype.status_formats[i];
+                                            rv[0].push(["div", {},
+                                                        ["label", {},
+                                                         ["input", {type:"checkbox", checked:"checked"}],
+                                                         status_number[status] + " ",
+                                                         ["span", {"class":status_class(status)}, status]]]);
+                                        }
+                                        i++;
+                                    }
+                                    return rv;
+                                },
+                               ];
+
+        log.appendChild(render(summary_template, {num_tests:tests.length}, output_document));
+
+        forEach(output_document.querySelectorAll("section#summary label"),
+                function(element)
+                {
+                    on_event(element, "click",
+                             function(e)
+                             {
+                                 if (output_document.getElementById("results") === null) {
+                                     e.preventDefault();
+                                     return;
+                                 }
+                                 var result_class = element.querySelector("span[class]").getAttribute("class");
+                                 var style_element = output_document.querySelector("style#hide-" + result_class);
+                                 var input_element = element.querySelector("input");
+                                 if (!style_element && !input_element.checked) {
+                                     style_element = output_document.createElementNS(xhtml_ns, "style");
+                                     style_element.id = "hide-" + result_class;
+                                     style_element.textContent = "table#results > tbody > tr.overall-"+result_class+"{display:none}";
+                                     output_document.body.appendChild(style_element);
+                                 } else if (style_element && input_element.checked) {
+                                     style_element.parentNode.removeChild(style_element);
+                                 }
+                             });
+                });
+
+        // This use of innerHTML plus manual escaping is not recommended in
+        // general, but is necessary here for performance.  Using textContent
+        // on each individual <td> adds tens of seconds of execution time for
+        // large test suites (tens of thousands of tests).
+        function escape_html(s)
+        {
+            return s.replace(/\&/g, "&amp;")
+                .replace(/</g, "&lt;")
+                .replace(/"/g, "&quot;")
+                .replace(/'/g, "&#39;");
+        }
+
+        function has_assertions()
+        {
+            for (var i = 0; i < tests.length; i++) {
+                if (tests[i].properties.hasOwnProperty("assert")) {
+                    return true;
+                }
+            }
+            return false;
+        }
+
+        function get_assertion(test)
+        {
+            if (test.properties.hasOwnProperty("assert")) {
+                if (Array.isArray(test.properties.assert)) {
+                    return test.properties.assert.join(' ');
+                }
+                return test.properties.assert;
+            }
+            return '';
+        }
+
+        var asserts_run_by_test = new Map();
+        asserts_run.forEach(assert => {
+            if (!asserts_run_by_test.has(assert.test)) {
+                asserts_run_by_test.set(assert.test, []);
+            }
+            asserts_run_by_test.get(assert.test).push(assert);
+        });
+
+        function get_asserts_output(test) {
+            var asserts = asserts_run_by_test.get(test);
+            if (!asserts) {
+                return "No asserts ran";
+            }
+            rv = "<table>";
+            rv += asserts.map(assert => {
+                var output_fn = "<strong>" + escape_html(assert.assert_name) + "</strong>(";
+                var prefix_len = output_fn.length;
+                var output_args = assert.args;
+                var output_len = output_args.reduce((prev, current) => prev+current, prefix_len);
+                if (output_len[output_len.length - 1] > 50) {
+                    output_args = output_args.map((x, i) =>
+                    (i > 0 ? "  ".repeat(prefix_len) : "" )+ x + (i < output_args.length - 1 ? ",\n" : ""));
+                } else {
+                    output_args = output_args.map((x, i) => x + (i < output_args.length - 1 ? ", " : ""));
+                }
+                output_fn += escape_html(output_args.join(""));
+                output_fn += ')';
+                var output_location;
+                if (assert.stack) {
+                    output_location = assert.stack.split("\n", 1)[0].replace(/@?\w+:\/\/[^ "\/]+(?::\d+)?/g, " ");
+                }
+                return "<tr class='overall-" +
+                    status_class(Test.prototype.status_formats[assert.status]) + "'>" +
+                    "<td class='" +
+                    status_class(Test.prototype.status_formats[assert.status]) + "'>" +
+                    Test.prototype.status_formats[assert.status] + "</td>" +
+                    "<td><pre>" +
+                    output_fn +
+                    (output_location ? "\n" + escape_html(output_location) : "") +
+                    "</pre></td></tr>";
+            }
+            ).join("\n");
+            rv += "</table>";
+            return rv;
+        }
+
+        log.appendChild(document.createElementNS(xhtml_ns, "section"));
+        var assertions = has_assertions();
+        var html = "<h2>Details</h2><table id='results' " + (assertions ? "class='assertions'" : "" ) + ">" +
+            "<thead><tr><th>Result</th><th>Test Name</th>" +
+            (assertions ? "<th>Assertion</th>" : "") +
+            "<th>Message</th></tr></thead>" +
+            "<tbody>";
+        for (var i = 0; i < tests.length; i++) {
+            var test = tests[i];
+            html += '<tr class="overall-' +
+                status_class(test.format_status()) +
+                '">' +
+                '<td class="' +
+                status_class(test.format_status()) +
+                '">' +
+                test.format_status() +
+                "</td><td>" +
+                escape_html(test.name) +
+                "</td><td>" +
+                (assertions ? escape_html(get_assertion(test)) + "</td><td>" : "") +
+                escape_html(test.message ? tests[i].message : " ") +
+                (tests[i].stack ? "<pre>" +
+                 escape_html(tests[i].stack) +
+                 "</pre>": "");
+            if (!(test instanceof RemoteTest)) {
+                 html += "<details><summary>Asserts run</summary>" + get_asserts_output(test) + "</details>"
+            }
+            html += "</td></tr>";
+        }
+        html += "</tbody></table>";
+        try {
+            log.lastChild.innerHTML = html;
+        } catch (e) {
+            log.appendChild(document.createElementNS(xhtml_ns, "p"))
+               .textContent = "Setting innerHTML for the log threw an exception.";
+            log.appendChild(document.createElementNS(xhtml_ns, "pre"))
+               .textContent = html;
+        }
+    };
+
+    /*
+     * Template code
+     *
+     * A template is just a JavaScript structure. An element is represented as:
+     *
+     * [tag_name, {attr_name:attr_value}, child1, child2]
+     *
+     * the children can either be strings (which act like text nodes), other templates or
+     * functions (see below)
+     *
+     * A text node is represented as
+     *
+     * ["{text}", value]
+     *
+     * String values have a simple substitution syntax; ${foo} represents a variable foo.
+     *
+     * It is possible to embed logic in templates by using a function in a place where a
+     * node would usually go. The function must either return part of a template or null.
+     *
+     * In cases where a set of nodes are required as output rather than a single node
+     * with children it is possible to just use a list
+     * [node1, node2, node3]
+     *
+     * Usage:
+     *
+     * render(template, substitutions) - take a template and an object mapping
+     * variable names to parameters and return either a DOM node or a list of DOM nodes
+     *
+     * substitute(template, substitutions) - take a template and variable mapping object,
+     * make the variable substitutions and return the substituted template
+     *
+     */
+
+    function is_single_node(template)
+    {
+        return typeof template[0] === "string";
+    }
+
+    function substitute(template, substitutions)
+    {
+        if (typeof template === "function") {
+            var replacement = template(substitutions);
+            if (!replacement) {
+                return null;
+            }
+
+            return substitute(replacement, substitutions);
+        }
+
+        if (is_single_node(template)) {
+            return substitute_single(template, substitutions);
+        }
+
+        return filter(map(template, function(x) {
+                              return substitute(x, substitutions);
+                          }), function(x) {return x !== null;});
+    }
+
+    function substitute_single(template, substitutions)
+    {
+        var substitution_re = /\$\{([^ }]*)\}/g;
+
+        function do_substitution(input) {
+            var components = input.split(substitution_re);
+            var rv = [];
+            for (var i = 0; i < components.length; i += 2) {
+                rv.push(components[i]);
+                if (components[i + 1]) {
+                    rv.push(String(substitutions[components[i + 1]]));
+                }
+            }
+            return rv;
+        }
+
+        function substitute_attrs(attrs, rv)
+        {
+            rv[1] = {};
+            for (var name in template[1]) {
+                if (attrs.hasOwnProperty(name)) {
+                    var new_name = do_substitution(name).join("");
+                    var new_value = do_substitution(attrs[name]).join("");
+                    rv[1][new_name] = new_value;
+                }
+            }
+        }
+
+        function substitute_children(children, rv)
+        {
+            for (var i = 0; i < children.length; i++) {
+                if (children[i] instanceof Object) {
+                    var replacement = substitute(children[i], substitutions);
+                    if (replacement !== null) {
+                        if (is_single_node(replacement)) {
+                            rv.push(replacement);
+                        } else {
+                            extend(rv, replacement);
+                        }
+                    }
+                } else {
+                    extend(rv, do_substitution(String(children[i])));
+                }
+            }
+            return rv;
+        }
+
+        var rv = [];
+        rv.push(do_substitution(String(template[0])).join(""));
+
+        if (template[0] === "{text}") {
+            substitute_children(template.slice(1), rv);
+        } else {
+            substitute_attrs(template[1], rv);
+            substitute_children(template.slice(2), rv);
+        }
+
+        return rv;
+    }
+
+    function make_dom_single(template, doc)
+    {
+        var output_document = doc || document;
+        var element;
+        if (template[0] === "{text}") {
+            element = output_document.createTextNode("");
+            for (var i = 1; i < template.length; i++) {
+                element.data += template[i];
+            }
+        } else {
+            element = output_document.createElementNS(xhtml_ns, template[0]);
+            for (var name in template[1]) {
+                if (template[1].hasOwnProperty(name)) {
+                    element.setAttribute(name, template[1][name]);
+                }
+            }
+            for (var i = 2; i < template.length; i++) {
+                if (template[i] instanceof Object) {
+                    var sub_element = make_dom(template[i]);
+                    element.appendChild(sub_element);
+                } else {
+                    var text_node = output_document.createTextNode(template[i]);
+                    element.appendChild(text_node);
+                }
+            }
+        }
+
+        return element;
+    }
+
+    function make_dom(template, substitutions, output_document)
+    {
+        if (is_single_node(template)) {
+            return make_dom_single(template, output_document);
+        }
+
+        return map(template, function(x) {
+                       return make_dom_single(x, output_document);
+                   });
+    }
+
+    function render(template, substitutions, output_document)
+    {
+        return make_dom(substitute(template, substitutions), output_document);
+    }
+
+    /*
+     * Utility functions
+     */
+    function assert(expected_true, function_name, description, error, substitutions)
+    {
+        if (expected_true !== true) {
+            var msg = make_message(function_name, description,
+                                   error, substitutions);
+            throw new AssertionError(msg);
+        }
+    }
+
+    /**
+     * @class
+     * Exception type that represents a failing assert.
+     *
+     * @param {string} message - Error message.
+     */
+    function AssertionError(message)
+    {
+        if (typeof message == "string") {
+            message = sanitize_unpaired_surrogates(message);
+        }
+        this.message = message;
+        this.stack = get_stack();
+    }
+    expose(AssertionError, "AssertionError");
+
+    AssertionError.prototype = Object.create(Error.prototype);
+
+    const get_stack = function() {
+        var stack = new Error().stack;
+
+        // 'Error.stack' is not supported in all browsers/versions
+        if (!stack) {
+            return "(Stack trace unavailable)";
+        }
+
+        var lines = stack.split("\n");
+
+        // Create a pattern to match stack frames originating within testharness.js.  These include the
+        // script URL, followed by the line/col (e.g., '/resources/testharness.js:120:21').
+        // Escape the URL per http://stackoverflow.com/questions/3561493/is-there-a-regexp-escape-function-in-javascript
+        // in case it contains RegExp characters.
+        var script_url = get_script_url();
+        var re_text = script_url ? script_url.replace(/[-\/\\^$*+?.()|[\]{}]/g, '\\$&') : "\\btestharness.js";
+        var re = new RegExp(re_text + ":\\d+:\\d+");
+
+        // Some browsers include a preamble that specifies the type of the error object.  Skip this by
+        // advancing until we find the first stack frame originating from testharness.js.
+        var i = 0;
+        while (!re.test(lines[i]) && i < lines.length) {
+            i++;
+        }
+
+        // Then skip the top frames originating from testharness.js to begin the stack at the test code.
+        while (re.test(lines[i]) && i < lines.length) {
+            i++;
+        }
+
+        // Paranoid check that we didn't skip all frames.  If so, return the original stack unmodified.
+        if (i >= lines.length) {
+            return stack;
+        }
+
+        return lines.slice(i).join("\n");
+    }
+
+    function OptionalFeatureUnsupportedError(message)
+    {
+        AssertionError.call(this, message);
+    }
+    OptionalFeatureUnsupportedError.prototype = Object.create(AssertionError.prototype);
+    expose(OptionalFeatureUnsupportedError, "OptionalFeatureUnsupportedError");
+
+    function make_message(function_name, description, error, substitutions)
+    {
+        for (var p in substitutions) {
+            if (substitutions.hasOwnProperty(p)) {
+                substitutions[p] = format_value(substitutions[p]);
+            }
+        }
+        var node_form = substitute(["{text}", "${function_name}: ${description}" + error],
+                                   merge({function_name:function_name,
+                                          description:(description?description + " ":"")},
+                                          substitutions));
+        return node_form.slice(1).join("");
+    }
+
+    function filter(array, callable, thisObj) {
+        var rv = [];
+        for (var i = 0; i < array.length; i++) {
+            if (array.hasOwnProperty(i)) {
+                var pass = callable.call(thisObj, array[i], i, array);
+                if (pass) {
+                    rv.push(array[i]);
+                }
+            }
+        }
+        return rv;
+    }
+
+    function map(array, callable, thisObj)
+    {
+        var rv = [];
+        rv.length = array.length;
+        for (var i = 0; i < array.length; i++) {
+            if (array.hasOwnProperty(i)) {
+                rv[i] = callable.call(thisObj, array[i], i, array);
+            }
+        }
+        return rv;
+    }
+
+    function extend(array, items)
+    {
+        Array.prototype.push.apply(array, items);
+    }
+
+    function forEach(array, callback, thisObj)
+    {
+        for (var i = 0; i < array.length; i++) {
+            if (array.hasOwnProperty(i)) {
+                callback.call(thisObj, array[i], i, array);
+            }
+        }
+    }
+
+    /**
+     * Immediately invoke a "iteratee" function with a series of values in
+     * parallel and invoke a final "done" function when all of the "iteratee"
+     * invocations have signaled completion.
+     *
+     * If all callbacks complete synchronously (or if no callbacks are
+     * specified), the ``done_callback`` will be invoked synchronously. It is the
+     * responsibility of the caller to ensure asynchronicity in cases where
+     * that is desired.
+     *
+     * @param {array} value Zero or more values to use in the invocation of
+     *                      ``iter_callback``
+     * @param {function} iter_callback A function that will be invoked
+     *                                 once for each of the values min
+     *                                 ``value``. Two arguments will
+     *                                 be available in each
+     *                                 invocation: the value from
+     *                                 ``value`` and a function that
+     *                                 must be invoked to signal
+     *                                 completion
+     * @param {function} done_callback A function that will be invoked after
+     *                                 all operations initiated by the
+     *                                 ``iter_callback`` function have signaled
+     *                                 completion
+     */
+    function all_async(values, iter_callback, done_callback)
+    {
+        var remaining = values.length;
+
+        if (remaining === 0) {
+            done_callback();
+        }
+
+        forEach(values,
+                function(element) {
+                    var invoked = false;
+                    var elDone = function() {
+                        if (invoked) {
+                            return;
+                        }
+
+                        invoked = true;
+                        remaining -= 1;
+
+                        if (remaining === 0) {
+                            done_callback();
+                        }
+                    };
+
+                    iter_callback(element, elDone);
+                });
+    }
+
+    function merge(a,b)
+    {
+        var rv = {};
+        var p;
+        for (p in a) {
+            rv[p] = a[p];
+        }
+        for (p in b) {
+            rv[p] = b[p];
+        }
+        return rv;
+    }
+
+    function expose(object, name)
+    {
+        var components = name.split(".");
+        var target = global_scope;
+        for (var i = 0; i < components.length - 1; i++) {
+            if (!(components[i] in target)) {
+                target[components[i]] = {};
+            }
+            target = target[components[i]];
+        }
+        target[components[components.length - 1]] = object;
+    }
+
+    function is_same_origin(w) {
+        try {
+            'random_prop' in w;
+            return true;
+        } catch (e) {
+            return false;
+        }
+    }
+
+    /** Returns the 'src' URL of the first <script> tag in the page to include the file 'testharness.js'. */
+    function get_script_url()
+    {
+        if (!('document' in global_scope)) {
+            return undefined;
+        }
+
+        var scripts = document.getElementsByTagName("script");
+        for (var i = 0; i < scripts.length; i++) {
+            var src;
+            if (scripts[i].src) {
+                src = scripts[i].src;
+            } else if (scripts[i].href) {
+                //SVG case
+                src = scripts[i].href.baseVal;
+            }
+
+            var matches = src && src.match(/^(.*\/|)testharness\.js$/);
+            if (matches) {
+                return src;
+            }
+        }
+        return undefined;
+    }
+
+    /** Returns the <title> or filename or "Untitled" */
+    function get_title()
+    {
+        if ('document' in global_scope) {
+            //Don't use document.title to work around an Opera/Presto bug in XHTML documents
+            var title = document.getElementsByTagName("title")[0];
+            if (title && title.firstChild && title.firstChild.data) {
+                return title.firstChild.data;
+            }
+        }
+        if ('META_TITLE' in global_scope && META_TITLE) {
+            return META_TITLE;
+        }
+        if ('location' in global_scope && 'pathname' in location) {
+            return location.pathname.substring(location.pathname.lastIndexOf('/') + 1, location.pathname.indexOf('.'));
+        }
+        return "Untitled";
+    }
+
+    /**
+     * Setup globals
+     */
+
+    var tests = new Tests();
+
+    if (global_scope.addEventListener) {
+        var error_handler = function(error, message, stack) {
+            var optional_unsupported = error instanceof OptionalFeatureUnsupportedError;
+            if (tests.file_is_test) {
+                var test = tests.tests[0];
+                if (test.phase >= test.phases.HAS_RESULT) {
+                    return;
+                }
+                var status = optional_unsupported ? test.PRECONDITION_FAILED : test.FAIL;
+                test.set_status(status, message, stack);
+                test.phase = test.phases.HAS_RESULT;
+            } else if (!tests.allow_uncaught_exception) {
+                var status = optional_unsupported ? tests.status.PRECONDITION_FAILED : tests.status.ERROR;
+                tests.status.status = status;
+                tests.status.message = message;
+                tests.status.stack = stack;
+            }
+
+            // Do not transition to the "complete" phase if the test has been
+            // configured to allow uncaught exceptions. This gives the test an
+            // opportunity to define subtests based on the exception reporting
+            // behavior.
+            if (!tests.allow_uncaught_exception) {
+                done();
+            }
+        };
+
+        addEventListener("error", function(e) {
+            var message = e.message;
+            var stack;
+            if (e.error && e.error.stack) {
+                stack = e.error.stack;
+            } else {
+                stack = e.filename + ":" + e.lineno + ":" + e.colno;
+            }
+            error_handler(e.error, message, stack);
+        }, false);
+
+        addEventListener("unhandledrejection", function(e) {
+            var message;
+            if (e.reason && e.reason.message) {
+                message = "Unhandled rejection: " + e.reason.message;
+            } else {
+                message = "Unhandled rejection";
+            }
+            var stack;
+            if (e.reason && e.reason.stack) {
+                stack = e.reason.stack;
+            }
+            error_handler(e.reason, message, stack);
+        }, false);
+    }
+
+    test_environment.on_tests_ready();
+
+    /**
+     * Stylesheet
+     */
+     var stylesheetContent = "\
+html {\
+    font-family:DejaVu Sans, Bitstream Vera Sans, Arial, Sans;\
+}\
+\
+#log .warning,\
+#log .warning a {\
+  color: black;\
+  background: yellow;\
+}\
+\
+#log .error,\
+#log .error a {\
+  color: white;\
+  background: red;\
+}\
+\
+section#summary {\
+    margin-bottom:1em;\
+}\
+\
+table#results {\
+    border-collapse:collapse;\
+    table-layout:fixed;\
+    width:100%;\
+}\
+\
+table#results > thead > tr > th:first-child,\
+table#results > tbody > tr > td:first-child {\
+    width:8em;\
+}\
+\
+table#results > thead > tr > th:last-child,\
+table#results > thead > tr > td:last-child {\
+    width:50%;\
+}\
+\
+table#results.assertions > thead > tr > th:last-child,\
+table#results.assertions > tbody > tr > td:last-child {\
+    width:35%;\
+}\
+\
+table#results > thead > > tr > th {\
+    padding:0;\
+    padding-bottom:0.5em;\
+    border-bottom:medium solid black;\
+}\
+\
+table#results > tbody > tr> td {\
+    padding:1em;\
+    padding-bottom:0.5em;\
+    border-bottom:thin solid black;\
+}\
+\
+.pass {\
+    color:green;\
+}\
+\
+.fail {\
+    color:red;\
+}\
+\
+tr.timeout {\
+    color:red;\
+}\
+\
+tr.notrun {\
+    color:blue;\
+}\
+\
+tr.optionalunsupported {\
+    color:blue;\
+}\
+\
+.ok {\
+    color:green;\
+}\
+\
+.error {\
+    color:red;\
+}\
+\
+.pass, .fail, .timeout, .notrun, .optionalunsupported .ok, .timeout, .error {\
+    font-variant:small-caps;\
+}\
+\
+table#results span {\
+    display:block;\
+}\
+\
+table#results span.expected {\
+    font-family:DejaVu Sans Mono, Bitstream Vera Sans Mono, Monospace;\
+    white-space:pre;\
+}\
+\
+table#results span.actual {\
+    font-family:DejaVu Sans Mono, Bitstream Vera Sans Mono, Monospace;\
+    white-space:pre;\
+}\
+";
+
+})(self);
+// vim: set expandtab shiftwidth=4 tabstop=4:
diff --git a/test/wpt/tests/resources/testharness.js.headers b/test/wpt/tests/resources/testharness.js.headers
new file mode 100644
index 0000000..5e8f640
--- /dev/null
+++ b/test/wpt/tests/resources/testharness.js.headers
@@ -0,0 +1,2 @@
+Content-Type: text/javascript; charset=utf-8
+Cache-Control: max-age=3600
diff --git a/test/wpt/tests/resources/testharnessreport.js b/test/wpt/tests/resources/testharnessreport.js
new file mode 100644
index 0000000..e5cb40f
--- /dev/null
+++ b/test/wpt/tests/resources/testharnessreport.js
@@ -0,0 +1,57 @@
+/* global add_completion_callback */
+/* global setup */
+
+/*
+ * This file is intended for vendors to implement code needed to integrate
+ * testharness.js tests with their own test systems.
+ *
+ * Typically test system integration will attach callbacks when each test has
+ * run, using add_result_callback(callback(test)), or when the whole test file
+ * has completed, using
+ * add_completion_callback(callback(tests, harness_status)).
+ *
+ * For more documentation about the callback functions and the
+ * parameters they are called with see testharness.js
+ */
+
+function dump_test_results(tests, status) {
+    var results_element = document.createElement("script");
+    results_element.type = "text/json";
+    results_element.id = "__testharness__results__";
+    var test_results = tests.map(function(x) {
+        return {name:x.name, status:x.status, message:x.message, stack:x.stack}
+    });
+    var data = {test:window.location.href,
+                tests:test_results,
+                status: status.status,
+                message: status.message,
+                stack: status.stack};
+    results_element.textContent = JSON.stringify(data);
+
+    // To avoid a HierarchyRequestError with XML documents, ensure that 'results_element'
+    // is inserted at a location that results in a valid document.
+    var parent = document.body
+        ? document.body                 // <body> is required in XHTML documents
+        : document.documentElement;     // fallback for optional <body> in HTML5, SVG, etc.
+
+    parent.appendChild(results_element);
+}
+
+add_completion_callback(dump_test_results);
+
+/* If the parent window has a testharness_properties object,
+ * we use this to provide the test settings. This is used by the
+ * default in-browser runner to configure the timeout and the
+ * rendering of results
+ */
+try {
+    if (window.opener && "testharness_properties" in window.opener) {
+        /* If we pass the testharness_properties object as-is here without
+         * JSON stringifying and reparsing it, IE fails & emits the message
+         * "Could not complete the operation due to error 80700019".
+         */
+        setup(JSON.parse(JSON.stringify(window.opener.testharness_properties)));
+    }
+} catch (e) {
+}
+// vim: set expandtab shiftwidth=4 tabstop=4:
diff --git a/test/wpt/tests/resources/testharnessreport.js.headers b/test/wpt/tests/resources/testharnessreport.js.headers
new file mode 100644
index 0000000..5e8f640
--- /dev/null
+++ b/test/wpt/tests/resources/testharnessreport.js.headers
@@ -0,0 +1,2 @@
+Content-Type: text/javascript; charset=utf-8
+Cache-Control: max-age=3600
diff --git a/test/wpt/tests/resources/webidl2/build.sh b/test/wpt/tests/resources/webidl2/build.sh
new file mode 100644
index 0000000..a631268
--- /dev/null
+++ b/test/wpt/tests/resources/webidl2/build.sh
@@ -0,0 +1,12 @@
+set -ex
+
+if [ ! -d "webidl2.js" ]; then
+  git clone https://github.com/w3c/webidl2.js.git
+fi
+cd webidl2.js
+npm install
+npm run build-debug
+HASH=$(git rev-parse HEAD)
+cd ..
+cp webidl2.js/dist/webidl2.js lib/
+echo "Currently using webidl2.js@${HASH}." > lib/VERSION.md
diff --git a/test/wpt/tests/resources/webidl2/lib/README.md b/test/wpt/tests/resources/webidl2/lib/README.md
new file mode 100644
index 0000000..1bd5832
--- /dev/null
+++ b/test/wpt/tests/resources/webidl2/lib/README.md
@@ -0,0 +1,4 @@
+This directory contains a built version of the [webidl2.js library](https://github.com/w3c/webidl2.js).
+It is built by running `npm run build-debug` at the root of that repository.
+
+The `webidl2.js.headers` file is a local addition to ensure the script is interpreted as UTF-8.
diff --git a/test/wpt/tests/resources/webidl2/lib/VERSION.md b/test/wpt/tests/resources/webidl2/lib/VERSION.md
new file mode 100644
index 0000000..5a3726c
--- /dev/null
+++ b/test/wpt/tests/resources/webidl2/lib/VERSION.md
@@ -0,0 +1 @@
+Currently using webidl2.js@6889aee6fc7d65915ab1267825248157dbc50486.
diff --git a/test/wpt/tests/resources/webidl2/lib/webidl2.js b/test/wpt/tests/resources/webidl2/lib/webidl2.js
new file mode 100644
index 0000000..7161def
--- /dev/null
+++ b/test/wpt/tests/resources/webidl2/lib/webidl2.js
@@ -0,0 +1,3824 @@
+(function webpackUniversalModuleDefinition(root, factory) {
+	if(typeof exports === 'object' && typeof module === 'object')
+		module.exports = factory();
+	else if(typeof define === 'function' && define.amd)
+		define([], factory);
+	else if(typeof exports === 'object')
+		exports["WebIDL2"] = factory();
+	else
+		root["WebIDL2"] = factory();
+})(globalThis, () => {
+return /******/ (() => { // webpackBootstrap
+/******/ 	"use strict";
+/******/ 	var __webpack_modules__ = ([
+/* 0 */,
+/* 1 */
+/***/ ((__unused_webpack___webpack_module__, __webpack_exports__, __webpack_require__) => {
+
+__webpack_require__.r(__webpack_exports__);
+/* harmony export */ __webpack_require__.d(__webpack_exports__, {
+/* harmony export */   "parse": () => (/* binding */ parse)
+/* harmony export */ });
+/* harmony import */ var _tokeniser_js__WEBPACK_IMPORTED_MODULE_0__ = __webpack_require__(2);
+/* harmony import */ var _productions_enum_js__WEBPACK_IMPORTED_MODULE_1__ = __webpack_require__(15);
+/* harmony import */ var _productions_includes_js__WEBPACK_IMPORTED_MODULE_2__ = __webpack_require__(16);
+/* harmony import */ var _productions_extended_attributes_js__WEBPACK_IMPORTED_MODULE_3__ = __webpack_require__(8);
+/* harmony import */ var _productions_typedef_js__WEBPACK_IMPORTED_MODULE_4__ = __webpack_require__(17);
+/* harmony import */ var _productions_callback_js__WEBPACK_IMPORTED_MODULE_5__ = __webpack_require__(18);
+/* harmony import */ var _productions_interface_js__WEBPACK_IMPORTED_MODULE_6__ = __webpack_require__(19);
+/* harmony import */ var _productions_mixin_js__WEBPACK_IMPORTED_MODULE_7__ = __webpack_require__(25);
+/* harmony import */ var _productions_dictionary_js__WEBPACK_IMPORTED_MODULE_8__ = __webpack_require__(26);
+/* harmony import */ var _productions_namespace_js__WEBPACK_IMPORTED_MODULE_9__ = __webpack_require__(28);
+/* harmony import */ var _productions_callback_interface_js__WEBPACK_IMPORTED_MODULE_10__ = __webpack_require__(29);
+/* harmony import */ var _productions_helpers_js__WEBPACK_IMPORTED_MODULE_11__ = __webpack_require__(4);
+/* harmony import */ var _productions_token_js__WEBPACK_IMPORTED_MODULE_12__ = __webpack_require__(10);
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+/**
+ * @param {Tokeniser} tokeniser
+ * @param {object} options
+ * @param {boolean} [options.concrete]
+ * @param {Function[]} [options.productions]
+ */
+function parseByTokens(tokeniser, options) {
+  const source = tokeniser.source;
+
+  function error(str) {
+    tokeniser.error(str);
+  }
+
+  function consume(...candidates) {
+    return tokeniser.consume(...candidates);
+  }
+
+  function callback() {
+    const callback = consume("callback");
+    if (!callback) return;
+    if (tokeniser.probe("interface")) {
+      return _productions_callback_interface_js__WEBPACK_IMPORTED_MODULE_10__.CallbackInterface.parse(tokeniser, callback);
+    }
+    return _productions_callback_js__WEBPACK_IMPORTED_MODULE_5__.CallbackFunction.parse(tokeniser, callback);
+  }
+
+  function interface_(opts) {
+    const base = consume("interface");
+    if (!base) return;
+    const ret =
+      _productions_mixin_js__WEBPACK_IMPORTED_MODULE_7__.Mixin.parse(tokeniser, base, opts) ||
+      _productions_interface_js__WEBPACK_IMPORTED_MODULE_6__.Interface.parse(tokeniser, base, opts) ||
+      error("Interface has no proper body");
+    return ret;
+  }
+
+  function partial() {
+    const partial = consume("partial");
+    if (!partial) return;
+    return (
+      _productions_dictionary_js__WEBPACK_IMPORTED_MODULE_8__.Dictionary.parse(tokeniser, { partial }) ||
+      interface_({ partial }) ||
+      _productions_namespace_js__WEBPACK_IMPORTED_MODULE_9__.Namespace.parse(tokeniser, { partial }) ||
+      error("Partial doesn't apply to anything")
+    );
+  }
+
+  function definition() {
+    if (options.productions) {
+      for (const production of options.productions) {
+        const result = production(tokeniser);
+        if (result) {
+          return result;
+        }
+      }
+    }
+
+    return (
+      callback() ||
+      interface_() ||
+      partial() ||
+      _productions_dictionary_js__WEBPACK_IMPORTED_MODULE_8__.Dictionary.parse(tokeniser) ||
+      _productions_enum_js__WEBPACK_IMPORTED_MODULE_1__.Enum.parse(tokeniser) ||
+      _productions_typedef_js__WEBPACK_IMPORTED_MODULE_4__.Typedef.parse(tokeniser) ||
+      _productions_includes_js__WEBPACK_IMPORTED_MODULE_2__.Includes.parse(tokeniser) ||
+      _productions_namespace_js__WEBPACK_IMPORTED_MODULE_9__.Namespace.parse(tokeniser)
+    );
+  }
+
+  function definitions() {
+    if (!source.length) return [];
+    const defs = [];
+    while (true) {
+      const ea = _productions_extended_attributes_js__WEBPACK_IMPORTED_MODULE_3__.ExtendedAttributes.parse(tokeniser);
+      const def = definition();
+      if (!def) {
+        if (ea.length) error("Stray extended attributes");
+        break;
+      }
+      (0,_productions_helpers_js__WEBPACK_IMPORTED_MODULE_11__.autoParenter)(def).extAttrs = ea;
+      defs.push(def);
+    }
+    const eof = _productions_token_js__WEBPACK_IMPORTED_MODULE_12__.Eof.parse(tokeniser);
+    if (options.concrete) {
+      defs.push(eof);
+    }
+    return defs;
+  }
+  const res = definitions();
+  if (tokeniser.position < source.length) error("Unrecognised tokens");
+  return res;
+}
+
+/**
+ * @param {string} str
+ * @param {object} [options]
+ * @param {*} [options.sourceName]
+ * @param {boolean} [options.concrete]
+ * @param {Function[]} [options.productions]
+ * @return {import("./productions/base.js").Base[]}
+ */
+function parse(str, options = {}) {
+  const tokeniser = new _tokeniser_js__WEBPACK_IMPORTED_MODULE_0__.Tokeniser(str);
+  if (typeof options.sourceName !== "undefined") {
+    // @ts-ignore (See Tokeniser.source in supplement.d.ts)
+    tokeniser.source.name = options.sourceName;
+  }
+  return parseByTokens(tokeniser, options);
+}
+
+
+/***/ }),
+/* 2 */
+/***/ ((__unused_webpack___webpack_module__, __webpack_exports__, __webpack_require__) => {
+
+__webpack_require__.r(__webpack_exports__);
+/* harmony export */ __webpack_require__.d(__webpack_exports__, {
+/* harmony export */   "Tokeniser": () => (/* binding */ Tokeniser),
+/* harmony export */   "WebIDLParseError": () => (/* binding */ WebIDLParseError),
+/* harmony export */   "argumentNameKeywords": () => (/* binding */ argumentNameKeywords),
+/* harmony export */   "stringTypes": () => (/* binding */ stringTypes),
+/* harmony export */   "typeNameKeywords": () => (/* binding */ typeNameKeywords)
+/* harmony export */ });
+/* harmony import */ var _error_js__WEBPACK_IMPORTED_MODULE_0__ = __webpack_require__(3);
+/* harmony import */ var _productions_helpers_js__WEBPACK_IMPORTED_MODULE_1__ = __webpack_require__(4);
+
+
+
+// These regular expressions use the sticky flag so they will only match at
+// the current location (ie. the offset of lastIndex).
+const tokenRe = {
+  // This expression uses a lookahead assertion to catch false matches
+  // against integers early.
+  decimal:
+    /-?(?=[0-9]*\.|[0-9]+[eE])(([0-9]+\.[0-9]*|[0-9]*\.[0-9]+)([Ee][-+]?[0-9]+)?|[0-9]+[Ee][-+]?[0-9]+)/y,
+  integer: /-?(0([Xx][0-9A-Fa-f]+|[0-7]*)|[1-9][0-9]*)/y,
+  identifier: /[_-]?[A-Za-z][0-9A-Z_a-z-]*/y,
+  string: /"[^"]*"/y,
+  whitespace: /[\t\n\r ]+/y,
+  comment: /\/\/.*|\/\*[\s\S]*?\*\//y,
+  other: /[^\t\n\r 0-9A-Za-z]/y,
+};
+
+const typeNameKeywords = [
+  "ArrayBuffer",
+  "DataView",
+  "Int8Array",
+  "Int16Array",
+  "Int32Array",
+  "Uint8Array",
+  "Uint16Array",
+  "Uint32Array",
+  "Uint8ClampedArray",
+  "BigInt64Array",
+  "BigUint64Array",
+  "Float32Array",
+  "Float64Array",
+  "any",
+  "object",
+  "symbol",
+];
+
+const stringTypes = ["ByteString", "DOMString", "USVString"];
+
+const argumentNameKeywords = [
+  "async",
+  "attribute",
+  "callback",
+  "const",
+  "constructor",
+  "deleter",
+  "dictionary",
+  "enum",
+  "getter",
+  "includes",
+  "inherit",
+  "interface",
+  "iterable",
+  "maplike",
+  "namespace",
+  "partial",
+  "required",
+  "setlike",
+  "setter",
+  "static",
+  "stringifier",
+  "typedef",
+  "unrestricted",
+];
+
+const nonRegexTerminals = [
+  "-Infinity",
+  "FrozenArray",
+  "Infinity",
+  "NaN",
+  "ObservableArray",
+  "Promise",
+  "bigint",
+  "boolean",
+  "byte",
+  "double",
+  "false",
+  "float",
+  "long",
+  "mixin",
+  "null",
+  "octet",
+  "optional",
+  "or",
+  "readonly",
+  "record",
+  "sequence",
+  "short",
+  "true",
+  "undefined",
+  "unsigned",
+  "void",
+].concat(argumentNameKeywords, stringTypes, typeNameKeywords);
+
+const punctuations = [
+  "(",
+  ")",
+  ",",
+  "...",
+  ":",
+  ";",
+  "<",
+  "=",
+  ">",
+  "?",
+  "*",
+  "[",
+  "]",
+  "{",
+  "}",
+];
+
+const reserved = [
+  // "constructor" is now a keyword
+  "_constructor",
+  "toString",
+  "_toString",
+];
+
+/**
+ * @typedef {ArrayItemType<ReturnType<typeof tokenise>>} Token
+ * @param {string} str
+ */
+function tokenise(str) {
+  const tokens = [];
+  let lastCharIndex = 0;
+  let trivia = "";
+  let line = 1;
+  let index = 0;
+  while (lastCharIndex < str.length) {
+    const nextChar = str.charAt(lastCharIndex);
+    let result = -1;
+
+    if (/[\t\n\r ]/.test(nextChar)) {
+      result = attemptTokenMatch("whitespace", { noFlushTrivia: true });
+    } else if (nextChar === "/") {
+      result = attemptTokenMatch("comment", { noFlushTrivia: true });
+    }
+
+    if (result !== -1) {
+      const currentTrivia = tokens.pop().value;
+      line += (currentTrivia.match(/\n/g) || []).length;
+      trivia += currentTrivia;
+      index -= 1;
+    } else if (/[-0-9.A-Z_a-z]/.test(nextChar)) {
+      result = attemptTokenMatch("decimal");
+      if (result === -1) {
+        result = attemptTokenMatch("integer");
+      }
+      if (result === -1) {
+        result = attemptTokenMatch("identifier");
+        const lastIndex = tokens.length - 1;
+        const token = tokens[lastIndex];
+        if (result !== -1) {
+          if (reserved.includes(token.value)) {
+            const message = `${(0,_productions_helpers_js__WEBPACK_IMPORTED_MODULE_1__.unescape)(
+              token.value
+            )} is a reserved identifier and must not be used.`;
+            throw new WebIDLParseError(
+              (0,_error_js__WEBPACK_IMPORTED_MODULE_0__.syntaxError)(tokens, lastIndex, null, message)
+            );
+          } else if (nonRegexTerminals.includes(token.value)) {
+            token.type = "inline";
+          }
+        }
+      }
+    } else if (nextChar === '"') {
+      result = attemptTokenMatch("string");
+    }
+
+    for (const punctuation of punctuations) {
+      if (str.startsWith(punctuation, lastCharIndex)) {
+        tokens.push({
+          type: "inline",
+          value: punctuation,
+          trivia,
+          line,
+          index,
+        });
+        trivia = "";
+        lastCharIndex += punctuation.length;
+        result = lastCharIndex;
+        break;
+      }
+    }
+
+    // other as the last try
+    if (result === -1) {
+      result = attemptTokenMatch("other");
+    }
+    if (result === -1) {
+      throw new Error("Token stream not progressing");
+    }
+    lastCharIndex = result;
+    index += 1;
+  }
+
+  // remaining trivia as eof
+  tokens.push({
+    type: "eof",
+    value: "",
+    trivia,
+    line,
+    index,
+  });
+
+  return tokens;
+
+  /**
+   * @param {keyof typeof tokenRe} type
+   * @param {object} options
+   * @param {boolean} [options.noFlushTrivia]
+   */
+  function attemptTokenMatch(type, { noFlushTrivia } = {}) {
+    const re = tokenRe[type];
+    re.lastIndex = lastCharIndex;
+    const result = re.exec(str);
+    if (result) {
+      tokens.push({ type, value: result[0], trivia, line, index });
+      if (!noFlushTrivia) {
+        trivia = "";
+      }
+      return re.lastIndex;
+    }
+    return -1;
+  }
+}
+
+class Tokeniser {
+  /**
+   * @param {string} idl
+   */
+  constructor(idl) {
+    this.source = tokenise(idl);
+    this.position = 0;
+  }
+
+  /**
+   * @param {string} message
+   * @return {never}
+   */
+  error(message) {
+    throw new WebIDLParseError(
+      (0,_error_js__WEBPACK_IMPORTED_MODULE_0__.syntaxError)(this.source, this.position, this.current, message)
+    );
+  }
+
+  /**
+   * @param {string} type
+   */
+  probeKind(type) {
+    return (
+      this.source.length > this.position &&
+      this.source[this.position].type === type
+    );
+  }
+
+  /**
+   * @param {string} value
+   */
+  probe(value) {
+    return (
+      this.probeKind("inline") && this.source[this.position].value === value
+    );
+  }
+
+  /**
+   * @param {...string} candidates
+   */
+  consumeKind(...candidates) {
+    for (const type of candidates) {
+      if (!this.probeKind(type)) continue;
+      const token = this.source[this.position];
+      this.position++;
+      return token;
+    }
+  }
+
+  /**
+   * @param {...string} candidates
+   */
+  consume(...candidates) {
+    if (!this.probeKind("inline")) return;
+    const token = this.source[this.position];
+    for (const value of candidates) {
+      if (token.value !== value) continue;
+      this.position++;
+      return token;
+    }
+  }
+
+  /**
+   * @param {string} value
+   */
+  consumeIdentifier(value) {
+    if (!this.probeKind("identifier")) {
+      return;
+    }
+    if (this.source[this.position].value !== value) {
+      return;
+    }
+    return this.consumeKind("identifier");
+  }
+
+  /**
+   * @param {number} position
+   */
+  unconsume(position) {
+    this.position = position;
+  }
+}
+
+class WebIDLParseError extends Error {
+  /**
+   * @param {object} options
+   * @param {string} options.message
+   * @param {string} options.bareMessage
+   * @param {string} options.context
+   * @param {number} options.line
+   * @param {*} options.sourceName
+   * @param {string} options.input
+   * @param {*[]} options.tokens
+   */
+  constructor({
+    message,
+    bareMessage,
+    context,
+    line,
+    sourceName,
+    input,
+    tokens,
+  }) {
+    super(message);
+
+    this.name = "WebIDLParseError"; // not to be mangled
+    this.bareMessage = bareMessage;
+    this.context = context;
+    this.line = line;
+    this.sourceName = sourceName;
+    this.input = input;
+    this.tokens = tokens;
+  }
+}
+
+
+/***/ }),
+/* 3 */
+/***/ ((__unused_webpack___webpack_module__, __webpack_exports__, __webpack_require__) => {
+
+__webpack_require__.r(__webpack_exports__);
+/* harmony export */ __webpack_require__.d(__webpack_exports__, {
+/* harmony export */   "syntaxError": () => (/* binding */ syntaxError),
+/* harmony export */   "validationError": () => (/* binding */ validationError)
+/* harmony export */ });
+/**
+ * @param {string} text
+ */
+function lastLine(text) {
+  const splitted = text.split("\n");
+  return splitted[splitted.length - 1];
+}
+
+function appendIfExist(base, target) {
+  let result = base;
+  if (target) {
+    result += ` ${target}`;
+  }
+  return result;
+}
+
+function contextAsText(node) {
+  const hierarchy = [node];
+  while (node && node.parent) {
+    const { parent } = node;
+    hierarchy.unshift(parent);
+    node = parent;
+  }
+  return hierarchy.map((n) => appendIfExist(n.type, n.name)).join(" -> ");
+}
+
+/**
+ * @typedef {object} WebIDL2ErrorOptions
+ * @property {"error" | "warning"} [level]
+ * @property {Function} [autofix]
+ * @property {string} [ruleName]
+ *
+ * @typedef {ReturnType<typeof error>} WebIDLErrorData
+ *
+ * @param {string} message error message
+ * @param {*} position
+ * @param {*} current
+ * @param {*} message
+ * @param {"Syntax" | "Validation"} kind error type
+ * @param {WebIDL2ErrorOptions=} options
+ */
+function error(
+  source,
+  position,
+  current,
+  message,
+  kind,
+  { level = "error", autofix, ruleName } = {}
+) {
+  /**
+   * @param {number} count
+   */
+  function sliceTokens(count) {
+    return count > 0
+      ? source.slice(position, position + count)
+      : source.slice(Math.max(position + count, 0), position);
+  }
+
+  /**
+   * @param {import("./tokeniser.js").Token[]} inputs
+   * @param {object} [options]
+   * @param {boolean} [options.precedes]
+   * @returns
+   */
+  function tokensToText(inputs, { precedes } = {}) {
+    const text = inputs.map((t) => t.trivia + t.value).join("");
+    const nextToken = source[position];
+    if (nextToken.type === "eof") {
+      return text;
+    }
+    if (precedes) {
+      return text + nextToken.trivia;
+    }
+    return text.slice(nextToken.trivia.length);
+  }
+
+  const maxTokens = 5; // arbitrary but works well enough
+  const line =
+    source[position].type !== "eof"
+      ? source[position].line
+      : source.length > 1
+      ? source[position - 1].line
+      : 1;
+
+  const precedingLastLine = lastLine(
+    tokensToText(sliceTokens(-maxTokens), { precedes: true })
+  );
+
+  const subsequentTokens = sliceTokens(maxTokens);
+  const subsequentText = tokensToText(subsequentTokens);
+  const subsequentFirstLine = subsequentText.split("\n")[0];
+
+  const spaced = " ".repeat(precedingLastLine.length) + "^";
+  const sourceContext = precedingLastLine + subsequentFirstLine + "\n" + spaced;
+
+  const contextType = kind === "Syntax" ? "since" : "inside";
+  const inSourceName = source.name ? ` in ${source.name}` : "";
+  const grammaticalContext =
+    current && current.name
+      ? `, ${contextType} \`${current.partial ? "partial " : ""}${contextAsText(
+          current
+        )}\``
+      : "";
+  const context = `${kind} error at line ${line}${inSourceName}${grammaticalContext}:\n${sourceContext}`;
+  return {
+    message: `${context} ${message}`,
+    bareMessage: message,
+    context,
+    line,
+    sourceName: source.name,
+    level,
+    ruleName,
+    autofix,
+    input: subsequentText,
+    tokens: subsequentTokens,
+  };
+}
+
+/**
+ * @param {string} message error message
+ */
+function syntaxError(source, position, current, message) {
+  return error(source, position, current, message, "Syntax");
+}
+
+/**
+ * @param {string} message error message
+ * @param {WebIDL2ErrorOptions} [options]
+ */
+function validationError(
+  token,
+  current,
+  ruleName,
+  message,
+  options = {}
+) {
+  options.ruleName = ruleName;
+  return error(
+    current.source,
+    token.index,
+    current,
+    message,
+    "Validation",
+    options
+  );
+}
+
+
+/***/ }),
+/* 4 */
+/***/ ((__unused_webpack___webpack_module__, __webpack_exports__, __webpack_require__) => {
+
+__webpack_require__.r(__webpack_exports__);
+/* harmony export */ __webpack_require__.d(__webpack_exports__, {
+/* harmony export */   "argument_list": () => (/* binding */ argument_list),
+/* harmony export */   "autoParenter": () => (/* binding */ autoParenter),
+/* harmony export */   "autofixAddExposedWindow": () => (/* binding */ autofixAddExposedWindow),
+/* harmony export */   "const_data": () => (/* binding */ const_data),
+/* harmony export */   "const_value": () => (/* binding */ const_value),
+/* harmony export */   "findLastIndex": () => (/* binding */ findLastIndex),
+/* harmony export */   "getFirstToken": () => (/* binding */ getFirstToken),
+/* harmony export */   "getLastIndentation": () => (/* binding */ getLastIndentation),
+/* harmony export */   "getMemberIndentation": () => (/* binding */ getMemberIndentation),
+/* harmony export */   "list": () => (/* binding */ list),
+/* harmony export */   "primitive_type": () => (/* binding */ primitive_type),
+/* harmony export */   "return_type": () => (/* binding */ return_type),
+/* harmony export */   "stringifier": () => (/* binding */ stringifier),
+/* harmony export */   "type_with_extended_attributes": () => (/* binding */ type_with_extended_attributes),
+/* harmony export */   "unescape": () => (/* binding */ unescape)
+/* harmony export */ });
+/* harmony import */ var _type_js__WEBPACK_IMPORTED_MODULE_0__ = __webpack_require__(5);
+/* harmony import */ var _argument_js__WEBPACK_IMPORTED_MODULE_1__ = __webpack_require__(11);
+/* harmony import */ var _extended_attributes_js__WEBPACK_IMPORTED_MODULE_2__ = __webpack_require__(8);
+/* harmony import */ var _operation_js__WEBPACK_IMPORTED_MODULE_3__ = __webpack_require__(13);
+/* harmony import */ var _attribute_js__WEBPACK_IMPORTED_MODULE_4__ = __webpack_require__(14);
+/* harmony import */ var _tokeniser_js__WEBPACK_IMPORTED_MODULE_5__ = __webpack_require__(2);
+
+
+
+
+
+
+
+/**
+ * @param {string} identifier
+ */
+function unescape(identifier) {
+  return identifier.startsWith("_") ? identifier.slice(1) : identifier;
+}
+
+/**
+ * Parses comma-separated list
+ * @param {import("../tokeniser.js").Tokeniser} tokeniser
+ * @param {object} args
+ * @param {Function} args.parser parser function for each item
+ * @param {boolean} [args.allowDangler] whether to allow dangling comma
+ * @param {string} [args.listName] the name to be shown on error messages
+ */
+function list(tokeniser, { parser, allowDangler, listName = "list" }) {
+  const first = parser(tokeniser);
+  if (!first) {
+    return [];
+  }
+  first.tokens.separator = tokeniser.consume(",");
+  const items = [first];
+  while (first.tokens.separator) {
+    const item = parser(tokeniser);
+    if (!item) {
+      if (!allowDangler) {
+        tokeniser.error(`Trailing comma in ${listName}`);
+      }
+      break;
+    }
+    item.tokens.separator = tokeniser.consume(",");
+    items.push(item);
+    if (!item.tokens.separator) break;
+  }
+  return items;
+}
+
+/**
+ * @param {import("../tokeniser.js").Tokeniser} tokeniser
+ */
+function const_value(tokeniser) {
+  return (
+    tokeniser.consumeKind("decimal", "integer") ||
+    tokeniser.consume("true", "false", "Infinity", "-Infinity", "NaN")
+  );
+}
+
+/**
+ * @param {object} token
+ * @param {string} token.type
+ * @param {string} token.value
+ */
+function const_data({ type, value }) {
+  switch (type) {
+    case "decimal":
+    case "integer":
+      return { type: "number", value };
+    case "string":
+      return { type: "string", value: value.slice(1, -1) };
+  }
+
+  switch (value) {
+    case "true":
+    case "false":
+      return { type: "boolean", value: value === "true" };
+    case "Infinity":
+    case "-Infinity":
+      return { type: "Infinity", negative: value.startsWith("-") };
+    case "[":
+      return { type: "sequence", value: [] };
+    case "{":
+      return { type: "dictionary" };
+    default:
+      return { type: value };
+  }
+}
+
+/**
+ * @param {import("../tokeniser.js").Tokeniser} tokeniser
+ */
+function primitive_type(tokeniser) {
+  function integer_type() {
+    const prefix = tokeniser.consume("unsigned");
+    const base = tokeniser.consume("short", "long");
+    if (base) {
+      const postfix = tokeniser.consume("long");
+      return new _type_js__WEBPACK_IMPORTED_MODULE_0__.Type({ source, tokens: { prefix, base, postfix } });
+    }
+    if (prefix) tokeniser.error("Failed to parse integer type");
+  }
+
+  function decimal_type() {
+    const prefix = tokeniser.consume("unrestricted");
+    const base = tokeniser.consume("float", "double");
+    if (base) {
+      return new _type_js__WEBPACK_IMPORTED_MODULE_0__.Type({ source, tokens: { prefix, base } });
+    }
+    if (prefix) tokeniser.error("Failed to parse float type");
+  }
+
+  const { source } = tokeniser;
+  const num_type = integer_type() || decimal_type();
+  if (num_type) return num_type;
+  const base = tokeniser.consume(
+    "bigint",
+    "boolean",
+    "byte",
+    "octet",
+    "undefined"
+  );
+  if (base) {
+    return new _type_js__WEBPACK_IMPORTED_MODULE_0__.Type({ source, tokens: { base } });
+  }
+}
+
+/**
+ * @param {import("../tokeniser.js").Tokeniser} tokeniser
+ */
+function argument_list(tokeniser) {
+  return list(tokeniser, {
+    parser: _argument_js__WEBPACK_IMPORTED_MODULE_1__.Argument.parse,
+    listName: "arguments list",
+  });
+}
+
+/**
+ * @param {import("../tokeniser.js").Tokeniser} tokeniser
+ * @param {string=} typeName (TODO: See Type.type for more details)
+ */
+function type_with_extended_attributes(tokeniser, typeName) {
+  const extAttrs = _extended_attributes_js__WEBPACK_IMPORTED_MODULE_2__.ExtendedAttributes.parse(tokeniser);
+  const ret = _type_js__WEBPACK_IMPORTED_MODULE_0__.Type.parse(tokeniser, typeName);
+  if (ret) autoParenter(ret).extAttrs = extAttrs;
+  return ret;
+}
+
+/**
+ * @param {import("../tokeniser.js").Tokeniser} tokeniser
+ * @param {string=} typeName (TODO: See Type.type for more details)
+ */
+function return_type(tokeniser, typeName) {
+  const typ = _type_js__WEBPACK_IMPORTED_MODULE_0__.Type.parse(tokeniser, typeName || "return-type");
+  if (typ) {
+    return typ;
+  }
+  const voidToken = tokeniser.consume("void");
+  if (voidToken) {
+    const ret = new _type_js__WEBPACK_IMPORTED_MODULE_0__.Type({
+      source: tokeniser.source,
+      tokens: { base: voidToken },
+    });
+    ret.type = "return-type";
+    return ret;
+  }
+}
+
+/**
+ * @param {import("../tokeniser.js").Tokeniser} tokeniser
+ */
+function stringifier(tokeniser) {
+  const special = tokeniser.consume("stringifier");
+  if (!special) return;
+  const member =
+    _attribute_js__WEBPACK_IMPORTED_MODULE_4__.Attribute.parse(tokeniser, { special }) ||
+    _operation_js__WEBPACK_IMPORTED_MODULE_3__.Operation.parse(tokeniser, { special }) ||
+    tokeniser.error("Unterminated stringifier");
+  return member;
+}
+
+/**
+ * @param {string} str
+ */
+function getLastIndentation(str) {
+  const lines = str.split("\n");
+  // the first line visually binds to the preceding token
+  if (lines.length) {
+    const match = lines[lines.length - 1].match(/^\s+/);
+    if (match) {
+      return match[0];
+    }
+  }
+  return "";
+}
+
+/**
+ * @param {string} parentTrivia
+ */
+function getMemberIndentation(parentTrivia) {
+  const indentation = getLastIndentation(parentTrivia);
+  const indentCh = indentation.includes("\t") ? "\t" : "  ";
+  return indentation + indentCh;
+}
+
+/**
+ * @param {import("./interface.js").Interface} def
+ */
+function autofixAddExposedWindow(def) {
+  return () => {
+    if (def.extAttrs.length) {
+      const tokeniser = new _tokeniser_js__WEBPACK_IMPORTED_MODULE_5__.Tokeniser("Exposed=Window,");
+      const exposed = _extended_attributes_js__WEBPACK_IMPORTED_MODULE_2__.SimpleExtendedAttribute.parse(tokeniser);
+      exposed.tokens.separator = tokeniser.consume(",");
+      const existing = def.extAttrs[0];
+      if (!/^\s/.test(existing.tokens.name.trivia)) {
+        existing.tokens.name.trivia = ` ${existing.tokens.name.trivia}`;
+      }
+      def.extAttrs.unshift(exposed);
+    } else {
+      autoParenter(def).extAttrs = _extended_attributes_js__WEBPACK_IMPORTED_MODULE_2__.ExtendedAttributes.parse(
+        new _tokeniser_js__WEBPACK_IMPORTED_MODULE_5__.Tokeniser("[Exposed=Window]")
+      );
+      const trivia = def.tokens.base.trivia;
+      def.extAttrs.tokens.open.trivia = trivia;
+      def.tokens.base.trivia = `\n${getLastIndentation(trivia)}`;
+    }
+  };
+}
+
+/**
+ * Get the first syntax token for the given IDL object.
+ * @param {*} data
+ */
+function getFirstToken(data) {
+  if (data.extAttrs.length) {
+    return data.extAttrs.tokens.open;
+  }
+  if (data.type === "operation" && !data.special) {
+    return getFirstToken(data.idlType);
+  }
+  const tokens = Object.values(data.tokens).sort((x, y) => x.index - y.index);
+  return tokens[0];
+}
+
+/**
+ * @template T
+ * @param {T[]} array
+ * @param {(item: T) => boolean} predicate
+ */
+function findLastIndex(array, predicate) {
+  const index = array.slice().reverse().findIndex(predicate);
+  if (index === -1) {
+    return index;
+  }
+  return array.length - index - 1;
+}
+
+/**
+ * Returns a proxy that auto-assign `parent` field.
+ * @template {Record<string | symbol, any>} T
+ * @param {T} data
+ * @param {*} [parent] The object that will be assigned to `parent`.
+ *                     If absent, it will be `data` by default.
+ * @return {T}
+ */
+function autoParenter(data, parent) {
+  if (!parent) {
+    // Defaults to `data` unless specified otherwise.
+    parent = data;
+  }
+  if (!data) {
+    // This allows `autoParenter(undefined)` which again allows
+    // `autoParenter(parse())` where the function may return nothing.
+    return data;
+  }
+  const proxy = new Proxy(data, {
+    get(target, p) {
+      const value = target[p];
+      if (Array.isArray(value) && p !== "source") {
+        // Wraps the array so that any added items will also automatically
+        // get their `parent` values.
+        return autoParenter(value, target);
+      }
+      return value;
+    },
+    set(target, p, value) {
+      // @ts-ignore https://github.com/microsoft/TypeScript/issues/47357
+      target[p] = value;
+      if (!value) {
+        return true;
+      } else if (Array.isArray(value)) {
+        // Assigning an array will add `parent` to its items.
+        for (const item of value) {
+          if (typeof item.parent !== "undefined") {
+            item.parent = parent;
+          }
+        }
+      } else if (typeof value.parent !== "undefined") {
+        value.parent = parent;
+      }
+      return true;
+    },
+  });
+  return proxy;
+}
+
+
+/***/ }),
+/* 5 */
+/***/ ((__unused_webpack___webpack_module__, __webpack_exports__, __webpack_require__) => {
+
+__webpack_require__.r(__webpack_exports__);
+/* harmony export */ __webpack_require__.d(__webpack_exports__, {
+/* harmony export */   "Type": () => (/* binding */ Type)
+/* harmony export */ });
+/* harmony import */ var _base_js__WEBPACK_IMPORTED_MODULE_0__ = __webpack_require__(6);
+/* harmony import */ var _helpers_js__WEBPACK_IMPORTED_MODULE_1__ = __webpack_require__(4);
+/* harmony import */ var _tokeniser_js__WEBPACK_IMPORTED_MODULE_2__ = __webpack_require__(2);
+/* harmony import */ var _error_js__WEBPACK_IMPORTED_MODULE_3__ = __webpack_require__(3);
+/* harmony import */ var _validators_helpers_js__WEBPACK_IMPORTED_MODULE_4__ = __webpack_require__(7);
+/* harmony import */ var _extended_attributes_js__WEBPACK_IMPORTED_MODULE_5__ = __webpack_require__(8);
+
+
+
+
+
+
+
+/**
+ * @param {import("../tokeniser.js").Tokeniser} tokeniser
+ * @param {string} typeName
+ */
+function generic_type(tokeniser, typeName) {
+  const base = tokeniser.consume(
+    "FrozenArray",
+    "ObservableArray",
+    "Promise",
+    "sequence",
+    "record"
+  );
+  if (!base) {
+    return;
+  }
+  const ret = (0,_helpers_js__WEBPACK_IMPORTED_MODULE_1__.autoParenter)(
+    new Type({ source: tokeniser.source, tokens: { base } })
+  );
+  ret.tokens.open =
+    tokeniser.consume("<") ||
+    tokeniser.error(`No opening bracket after ${base.value}`);
+  switch (base.value) {
+    case "Promise": {
+      if (tokeniser.probe("["))
+        tokeniser.error("Promise type cannot have extended attribute");
+      const subtype =
+        (0,_helpers_js__WEBPACK_IMPORTED_MODULE_1__.return_type)(tokeniser, typeName) ||
+        tokeniser.error("Missing Promise subtype");
+      ret.subtype.push(subtype);
+      break;
+    }
+    case "sequence":
+    case "FrozenArray":
+    case "ObservableArray": {
+      const subtype =
+        (0,_helpers_js__WEBPACK_IMPORTED_MODULE_1__.type_with_extended_attributes)(tokeniser, typeName) ||
+        tokeniser.error(`Missing ${base.value} subtype`);
+      ret.subtype.push(subtype);
+      break;
+    }
+    case "record": {
+      if (tokeniser.probe("["))
+        tokeniser.error("Record key cannot have extended attribute");
+      const keyType =
+        tokeniser.consume(..._tokeniser_js__WEBPACK_IMPORTED_MODULE_2__.stringTypes) ||
+        tokeniser.error(`Record key must be one of: ${_tokeniser_js__WEBPACK_IMPORTED_MODULE_2__.stringTypes.join(", ")}`);
+      const keyIdlType = new Type({
+        source: tokeniser.source,
+        tokens: { base: keyType },
+      });
+      keyIdlType.tokens.separator =
+        tokeniser.consume(",") ||
+        tokeniser.error("Missing comma after record key type");
+      keyIdlType.type = typeName;
+      const valueType =
+        (0,_helpers_js__WEBPACK_IMPORTED_MODULE_1__.type_with_extended_attributes)(tokeniser, typeName) ||
+        tokeniser.error("Error parsing generic type record");
+      ret.subtype.push(keyIdlType, valueType);
+      break;
+    }
+  }
+  if (!ret.idlType) tokeniser.error(`Error parsing generic type ${base.value}`);
+  ret.tokens.close =
+    tokeniser.consume(">") ||
+    tokeniser.error(`Missing closing bracket after ${base.value}`);
+  return ret.this;
+}
+
+/**
+ * @param {import("../tokeniser.js").Tokeniser} tokeniser
+ */
+function type_suffix(tokeniser, obj) {
+  const nullable = tokeniser.consume("?");
+  if (nullable) {
+    obj.tokens.nullable = nullable;
+  }
+  if (tokeniser.probe("?")) tokeniser.error("Can't nullable more than once");
+}
+
+/**
+ * @param {import("../tokeniser.js").Tokeniser} tokeniser
+ * @param {string} typeName
+ */
+function single_type(tokeniser, typeName) {
+  let ret = generic_type(tokeniser, typeName) || (0,_helpers_js__WEBPACK_IMPORTED_MODULE_1__.primitive_type)(tokeniser);
+  if (!ret) {
+    const base =
+      tokeniser.consumeKind("identifier") ||
+      tokeniser.consume(..._tokeniser_js__WEBPACK_IMPORTED_MODULE_2__.stringTypes, ..._tokeniser_js__WEBPACK_IMPORTED_MODULE_2__.typeNameKeywords);
+    if (!base) {
+      return;
+    }
+    ret = new Type({ source: tokeniser.source, tokens: { base } });
+    if (tokeniser.probe("<"))
+      tokeniser.error(`Unsupported generic type ${base.value}`);
+  }
+  if (ret.generic === "Promise" && tokeniser.probe("?")) {
+    tokeniser.error("Promise type cannot be nullable");
+  }
+  ret.type = typeName || null;
+  type_suffix(tokeniser, ret);
+  if (ret.nullable && ret.idlType === "any")
+    tokeniser.error("Type `any` cannot be made nullable");
+  return ret;
+}
+
+/**
+ * @param {import("../tokeniser.js").Tokeniser} tokeniser
+ * @param {string} type
+ */
+function union_type(tokeniser, type) {
+  const tokens = {};
+  tokens.open = tokeniser.consume("(");
+  if (!tokens.open) return;
+  const ret = (0,_helpers_js__WEBPACK_IMPORTED_MODULE_1__.autoParenter)(new Type({ source: tokeniser.source, tokens }));
+  ret.type = type || null;
+  while (true) {
+    const typ =
+      (0,_helpers_js__WEBPACK_IMPORTED_MODULE_1__.type_with_extended_attributes)(tokeniser) ||
+      tokeniser.error("No type after open parenthesis or 'or' in union type");
+    if (typ.idlType === "any")
+      tokeniser.error("Type `any` cannot be included in a union type");
+    if (typ.generic === "Promise")
+      tokeniser.error("Type `Promise` cannot be included in a union type");
+    ret.subtype.push(typ);
+    const or = tokeniser.consume("or");
+    if (or) {
+      typ.tokens.separator = or;
+    } else break;
+  }
+  if (ret.idlType.length < 2) {
+    tokeniser.error(
+      "At least two types are expected in a union type but found less"
+    );
+  }
+  tokens.close =
+    tokeniser.consume(")") || tokeniser.error("Unterminated union type");
+  type_suffix(tokeniser, ret);
+  return ret.this;
+}
+
+class Type extends _base_js__WEBPACK_IMPORTED_MODULE_0__.Base {
+  /**
+   * @param {import("../tokeniser.js").Tokeniser} tokeniser
+   * @param {string} typeName
+   */
+  static parse(tokeniser, typeName) {
+    return single_type(tokeniser, typeName) || union_type(tokeniser, typeName);
+  }
+
+  constructor({ source, tokens }) {
+    super({ source, tokens });
+    Object.defineProperty(this, "subtype", { value: [], writable: true });
+    this.extAttrs = new _extended_attributes_js__WEBPACK_IMPORTED_MODULE_5__.ExtendedAttributes({ source, tokens: {} });
+  }
+
+  get generic() {
+    if (this.subtype.length && this.tokens.base) {
+      return this.tokens.base.value;
+    }
+    return "";
+  }
+  get nullable() {
+    return Boolean(this.tokens.nullable);
+  }
+  get union() {
+    return Boolean(this.subtype.length) && !this.tokens.base;
+  }
+  get idlType() {
+    if (this.subtype.length) {
+      return this.subtype;
+    }
+    // Adding prefixes/postfixes for "unrestricted float", etc.
+    const name = [this.tokens.prefix, this.tokens.base, this.tokens.postfix]
+      .filter((t) => t)
+      .map((t) => t.value)
+      .join(" ");
+    return (0,_helpers_js__WEBPACK_IMPORTED_MODULE_1__.unescape)(name);
+  }
+
+  *validate(defs) {
+    yield* this.extAttrs.validate(defs);
+
+    if (this.idlType === "void") {
+      const message = `\`void\` is now replaced by \`undefined\`. Refer to the \
+[relevant GitHub issue](https://github.com/whatwg/webidl/issues/60) \
+for more information.`;
+      yield (0,_error_js__WEBPACK_IMPORTED_MODULE_3__.validationError)(this.tokens.base, this, "replace-void", message, {
+        autofix: replaceVoid(this),
+      });
+    }
+
+    /*
+     * If a union is nullable, its subunions cannot include a dictionary
+     * If not, subunions may include dictionaries if each union is not nullable
+     */
+    const typedef = !this.union && defs.unique.get(this.idlType);
+    const target = this.union
+      ? this
+      : typedef && typedef.type === "typedef"
+      ? typedef.idlType
+      : undefined;
+    if (target && this.nullable) {
+      // do not allow any dictionary
+      const { reference } = (0,_validators_helpers_js__WEBPACK_IMPORTED_MODULE_4__.idlTypeIncludesDictionary)(target, defs) || {};
+      if (reference) {
+        const targetToken = (this.union ? reference : this).tokens.base;
+        const message = "Nullable union cannot include a dictionary type.";
+        yield (0,_error_js__WEBPACK_IMPORTED_MODULE_3__.validationError)(
+          targetToken,
+          this,
+          "no-nullable-union-dict",
+          message
+        );
+      }
+    } else {
+      // allow some dictionary
+      for (const subtype of this.subtype) {
+        yield* subtype.validate(defs);
+      }
+    }
+  }
+
+  /** @param {import("../writer.js").Writer} w */
+  write(w) {
+    const type_body = () => {
+      if (this.union || this.generic) {
+        return w.ts.wrap([
+          w.token(this.tokens.base, w.ts.generic),
+          w.token(this.tokens.open),
+          ...this.subtype.map((t) => t.write(w)),
+          w.token(this.tokens.close),
+        ]);
+      }
+      const firstToken = this.tokens.prefix || this.tokens.base;
+      const prefix = this.tokens.prefix
+        ? [this.tokens.prefix.value, w.ts.trivia(this.tokens.base.trivia)]
+        : [];
+      const ref = w.reference(
+        w.ts.wrap([
+          ...prefix,
+          this.tokens.base.value,
+          w.token(this.tokens.postfix),
+        ]),
+        {
+          unescaped: /** @type {string} (because it's not union) */ (
+            this.idlType
+          ),
+          context: this,
+        }
+      );
+      return w.ts.wrap([w.ts.trivia(firstToken.trivia), ref]);
+    };
+    return w.ts.wrap([
+      this.extAttrs.write(w),
+      type_body(),
+      w.token(this.tokens.nullable),
+      w.token(this.tokens.separator),
+    ]);
+  }
+}
+
+/**
+ * @param {Type} type
+ */
+function replaceVoid(type) {
+  return () => {
+    type.tokens.base.value = "undefined";
+  };
+}
+
+
+/***/ }),
+/* 6 */
+/***/ ((__unused_webpack___webpack_module__, __webpack_exports__, __webpack_require__) => {
+
+__webpack_require__.r(__webpack_exports__);
+/* harmony export */ __webpack_require__.d(__webpack_exports__, {
+/* harmony export */   "Base": () => (/* binding */ Base)
+/* harmony export */ });
+class Base {
+  /**
+   * @param {object} initializer
+   * @param {Base["source"]} initializer.source
+   * @param {Base["tokens"]} initializer.tokens
+   */
+  constructor({ source, tokens }) {
+    Object.defineProperties(this, {
+      source: { value: source },
+      tokens: { value: tokens, writable: true },
+      parent: { value: null, writable: true },
+      this: { value: this }, // useful when escaping from proxy
+    });
+  }
+
+  toJSON() {
+    const json = { type: undefined, name: undefined, inheritance: undefined };
+    let proto = this;
+    while (proto !== Object.prototype) {
+      const descMap = Object.getOwnPropertyDescriptors(proto);
+      for (const [key, value] of Object.entries(descMap)) {
+        if (value.enumerable || value.get) {
+          // @ts-ignore - allow indexing here
+          json[key] = this[key];
+        }
+      }
+      proto = Object.getPrototypeOf(proto);
+    }
+    return json;
+  }
+}
+
+
+/***/ }),
+/* 7 */
+/***/ ((__unused_webpack___webpack_module__, __webpack_exports__, __webpack_require__) => {
+
+__webpack_require__.r(__webpack_exports__);
+/* harmony export */ __webpack_require__.d(__webpack_exports__, {
+/* harmony export */   "dictionaryIncludesRequiredField": () => (/* binding */ dictionaryIncludesRequiredField),
+/* harmony export */   "idlTypeIncludesDictionary": () => (/* binding */ idlTypeIncludesDictionary)
+/* harmony export */ });
+/**
+ * @typedef {import("../productions/dictionary.js").Dictionary} Dictionary
+ *
+ * @param {*} idlType
+ * @param {import("../validator.js").Definitions} defs
+ * @param {object} [options]
+ * @param {boolean} [options.useNullableInner] use when the input idlType is nullable and you want to use its inner type
+ * @return {{ reference: *, dictionary: Dictionary }} the type reference that ultimately includes dictionary.
+ */
+function idlTypeIncludesDictionary(
+  idlType,
+  defs,
+  { useNullableInner } = {}
+) {
+  if (!idlType.union) {
+    const def = defs.unique.get(idlType.idlType);
+    if (!def) {
+      return;
+    }
+    if (def.type === "typedef") {
+      const { typedefIncludesDictionary } = defs.cache;
+      if (typedefIncludesDictionary.has(def)) {
+        // Note that this also halts when it met indeterminate state
+        // to prevent infinite recursion
+        return typedefIncludesDictionary.get(def);
+      }
+      defs.cache.typedefIncludesDictionary.set(def, undefined); // indeterminate state
+      const result = idlTypeIncludesDictionary(def.idlType, defs);
+      defs.cache.typedefIncludesDictionary.set(def, result);
+      if (result) {
+        return {
+          reference: idlType,
+          dictionary: result.dictionary,
+        };
+      }
+    }
+    if (def.type === "dictionary" && (useNullableInner || !idlType.nullable)) {
+      return {
+        reference: idlType,
+        dictionary: def,
+      };
+    }
+  }
+  for (const subtype of idlType.subtype) {
+    const result = idlTypeIncludesDictionary(subtype, defs);
+    if (result) {
+      if (subtype.union) {
+        return result;
+      }
+      return {
+        reference: subtype,
+        dictionary: result.dictionary,
+      };
+    }
+  }
+}
+
+/**
+ * @param {*} dict dictionary type
+ * @param {import("../validator.js").Definitions} defs
+ * @return {boolean}
+ */
+function dictionaryIncludesRequiredField(dict, defs) {
+  if (defs.cache.dictionaryIncludesRequiredField.has(dict)) {
+    return defs.cache.dictionaryIncludesRequiredField.get(dict);
+  }
+  // Set cached result to indeterminate to short-circuit circular definitions.
+  // The final result will be updated to true or false.
+  defs.cache.dictionaryIncludesRequiredField.set(dict, undefined);
+  let result = dict.members.some((field) => field.required);
+  if (!result && dict.inheritance) {
+    const superdict = defs.unique.get(dict.inheritance);
+    if (!superdict) {
+      // Assume required members in the supertype if it is unknown.
+      result = true;
+    } else if (dictionaryIncludesRequiredField(superdict, defs)) {
+      result = true;
+    }
+  }
+  defs.cache.dictionaryIncludesRequiredField.set(dict, result);
+  return result;
+}
+
+
+/***/ }),
+/* 8 */
+/***/ ((__unused_webpack___webpack_module__, __webpack_exports__, __webpack_require__) => {
+
+__webpack_require__.r(__webpack_exports__);
+/* harmony export */ __webpack_require__.d(__webpack_exports__, {
+/* harmony export */   "ExtendedAttributeParameters": () => (/* binding */ ExtendedAttributeParameters),
+/* harmony export */   "ExtendedAttributes": () => (/* binding */ ExtendedAttributes),
+/* harmony export */   "SimpleExtendedAttribute": () => (/* binding */ SimpleExtendedAttribute)
+/* harmony export */ });
+/* harmony import */ var _base_js__WEBPACK_IMPORTED_MODULE_0__ = __webpack_require__(6);
+/* harmony import */ var _array_base_js__WEBPACK_IMPORTED_MODULE_1__ = __webpack_require__(9);
+/* harmony import */ var _token_js__WEBPACK_IMPORTED_MODULE_2__ = __webpack_require__(10);
+/* harmony import */ var _helpers_js__WEBPACK_IMPORTED_MODULE_3__ = __webpack_require__(4);
+/* harmony import */ var _error_js__WEBPACK_IMPORTED_MODULE_4__ = __webpack_require__(3);
+
+
+
+
+
+
+/**
+ * @param {import("../tokeniser.js").Tokeniser} tokeniser
+ * @param {string} tokenName
+ */
+function tokens(tokeniser, tokenName) {
+  return (0,_helpers_js__WEBPACK_IMPORTED_MODULE_3__.list)(tokeniser, {
+    parser: _token_js__WEBPACK_IMPORTED_MODULE_2__.WrappedToken.parser(tokeniser, tokenName),
+    listName: tokenName + " list",
+  });
+}
+
+const extAttrValueSyntax = ["identifier", "decimal", "integer", "string"];
+
+const shouldBeLegacyPrefixed = [
+  "NoInterfaceObject",
+  "LenientSetter",
+  "LenientThis",
+  "TreatNonObjectAsNull",
+  "Unforgeable",
+];
+
+const renamedLegacies = new Map([
+  .../** @type {[string, string][]} */ (
+    shouldBeLegacyPrefixed.map((name) => [name, `Legacy${name}`])
+  ),
+  ["NamedConstructor", "LegacyFactoryFunction"],
+  ["OverrideBuiltins", "LegacyOverrideBuiltIns"],
+  ["TreatNullAs", "LegacyNullToEmptyString"],
+]);
+
+/**
+ * This will allow a set of extended attribute values to be parsed.
+ * @param {import("../tokeniser.js").Tokeniser} tokeniser
+ */
+function extAttrListItems(tokeniser) {
+  for (const syntax of extAttrValueSyntax) {
+    const toks = tokens(tokeniser, syntax);
+    if (toks.length) {
+      return toks;
+    }
+  }
+  tokeniser.error(
+    `Expected identifiers, strings, decimals, or integers but none found`
+  );
+}
+
+class ExtendedAttributeParameters extends _base_js__WEBPACK_IMPORTED_MODULE_0__.Base {
+  /**
+   * @param {import("../tokeniser.js").Tokeniser} tokeniser
+   */
+  static parse(tokeniser) {
+    const tokens = { assign: tokeniser.consume("=") };
+    const ret = (0,_helpers_js__WEBPACK_IMPORTED_MODULE_3__.autoParenter)(
+      new ExtendedAttributeParameters({ source: tokeniser.source, tokens })
+    );
+    ret.list = [];
+    if (tokens.assign) {
+      tokens.asterisk = tokeniser.consume("*");
+      if (tokens.asterisk) {
+        return ret.this;
+      }
+      tokens.secondaryName = tokeniser.consumeKind(...extAttrValueSyntax);
+    }
+    tokens.open = tokeniser.consume("(");
+    if (tokens.open) {
+      ret.list = ret.rhsIsList
+        ? // [Exposed=(Window,Worker)]
+          extAttrListItems(tokeniser)
+        : // [LegacyFactoryFunction=Audio(DOMString src)] or [Constructor(DOMString str)]
+          (0,_helpers_js__WEBPACK_IMPORTED_MODULE_3__.argument_list)(tokeniser);
+      tokens.close =
+        tokeniser.consume(")") ||
+        tokeniser.error("Unexpected token in extended attribute argument list");
+    } else if (tokens.assign && !tokens.secondaryName) {
+      tokeniser.error("No right hand side to extended attribute assignment");
+    }
+    return ret.this;
+  }
+
+  get rhsIsList() {
+    return (
+      this.tokens.assign && !this.tokens.asterisk && !this.tokens.secondaryName
+    );
+  }
+
+  get rhsType() {
+    if (this.rhsIsList) {
+      return this.list[0].tokens.value.type + "-list";
+    }
+    if (this.tokens.asterisk) {
+      return "*";
+    }
+    if (this.tokens.secondaryName) {
+      return this.tokens.secondaryName.type;
+    }
+    return null;
+  }
+
+  /** @param {import("../writer.js").Writer} w */
+  write(w) {
+    const { rhsType } = this;
+    return w.ts.wrap([
+      w.token(this.tokens.assign),
+      w.token(this.tokens.asterisk),
+      w.reference_token(this.tokens.secondaryName, this.parent),
+      w.token(this.tokens.open),
+      ...this.list.map((p) => {
+        return rhsType === "identifier-list"
+          ? w.identifier(p, this.parent)
+          : p.write(w);
+      }),
+      w.token(this.tokens.close),
+    ]);
+  }
+}
+
+class SimpleExtendedAttribute extends _base_js__WEBPACK_IMPORTED_MODULE_0__.Base {
+  /**
+   * @param {import("../tokeniser.js").Tokeniser} tokeniser
+   */
+  static parse(tokeniser) {
+    const name = tokeniser.consumeKind("identifier");
+    if (name) {
+      return new SimpleExtendedAttribute({
+        source: tokeniser.source,
+        tokens: { name },
+        params: ExtendedAttributeParameters.parse(tokeniser),
+      });
+    }
+  }
+
+  constructor({ source, tokens, params }) {
+    super({ source, tokens });
+    params.parent = this;
+    Object.defineProperty(this, "params", { value: params });
+  }
+
+  get type() {
+    return "extended-attribute";
+  }
+  get name() {
+    return this.tokens.name.value;
+  }
+  get rhs() {
+    const { rhsType: type, tokens, list } = this.params;
+    if (!type) {
+      return null;
+    }
+    const value = this.params.rhsIsList
+      ? list
+      : this.params.tokens.secondaryName
+      ? (0,_helpers_js__WEBPACK_IMPORTED_MODULE_3__.unescape)(tokens.secondaryName.value)
+      : null;
+    return { type, value };
+  }
+  get arguments() {
+    const { rhsIsList, list } = this.params;
+    if (!list || rhsIsList) {
+      return [];
+    }
+    return list;
+  }
+
+  *validate(defs) {
+    const { name } = this;
+    if (name === "LegacyNoInterfaceObject") {
+      const message = `\`[LegacyNoInterfaceObject]\` extended attribute is an \
+undesirable feature that may be removed from Web IDL in the future. Refer to the \
+[relevant upstream PR](https://github.com/whatwg/webidl/pull/609) for more \
+information.`;
+      yield (0,_error_js__WEBPACK_IMPORTED_MODULE_4__.validationError)(
+        this.tokens.name,
+        this,
+        "no-nointerfaceobject",
+        message,
+        { level: "warning" }
+      );
+    } else if (renamedLegacies.has(name)) {
+      const message = `\`[${name}]\` extended attribute is a legacy feature \
+that is now renamed to \`[${renamedLegacies.get(name)}]\`. Refer to the \
+[relevant upstream PR](https://github.com/whatwg/webidl/pull/870) for more \
+information.`;
+      yield (0,_error_js__WEBPACK_IMPORTED_MODULE_4__.validationError)(this.tokens.name, this, "renamed-legacy", message, {
+        level: "warning",
+        autofix: renameLegacyExtendedAttribute(this),
+      });
+    }
+    for (const arg of this.arguments) {
+      yield* arg.validate(defs);
+    }
+  }
+
+  /** @param {import("../writer.js").Writer} w */
+  write(w) {
+    return w.ts.wrap([
+      w.ts.trivia(this.tokens.name.trivia),
+      w.ts.extendedAttribute(
+        w.ts.wrap([
+          w.ts.extendedAttributeReference(this.name),
+          this.params.write(w),
+        ])
+      ),
+      w.token(this.tokens.separator),
+    ]);
+  }
+}
+
+/**
+ * @param {SimpleExtendedAttribute} extAttr
+ */
+function renameLegacyExtendedAttribute(extAttr) {
+  return () => {
+    const { name } = extAttr;
+    extAttr.tokens.name.value = renamedLegacies.get(name);
+    if (name === "TreatNullAs") {
+      extAttr.params.tokens = {};
+    }
+  };
+}
+
+// Note: we parse something simpler than the official syntax. It's all that ever
+// seems to be used
+class ExtendedAttributes extends _array_base_js__WEBPACK_IMPORTED_MODULE_1__.ArrayBase {
+  /**
+   * @param {import("../tokeniser.js").Tokeniser} tokeniser
+   */
+  static parse(tokeniser) {
+    const tokens = {};
+    tokens.open = tokeniser.consume("[");
+    const ret = new ExtendedAttributes({ source: tokeniser.source, tokens });
+    if (!tokens.open) return ret;
+    ret.push(
+      ...(0,_helpers_js__WEBPACK_IMPORTED_MODULE_3__.list)(tokeniser, {
+        parser: SimpleExtendedAttribute.parse,
+        listName: "extended attribute",
+      })
+    );
+    tokens.close =
+      tokeniser.consume("]") ||
+      tokeniser.error(
+        "Expected a closing token for the extended attribute list"
+      );
+    if (!ret.length) {
+      tokeniser.unconsume(tokens.close.index);
+      tokeniser.error("An extended attribute list must not be empty");
+    }
+    if (tokeniser.probe("[")) {
+      tokeniser.error(
+        "Illegal double extended attribute lists, consider merging them"
+      );
+    }
+    return ret;
+  }
+
+  *validate(defs) {
+    for (const extAttr of this) {
+      yield* extAttr.validate(defs);
+    }
+  }
+
+  /** @param {import("../writer.js").Writer} w */
+  write(w) {
+    if (!this.length) return "";
+    return w.ts.wrap([
+      w.token(this.tokens.open),
+      ...this.map((ea) => ea.write(w)),
+      w.token(this.tokens.close),
+    ]);
+  }
+}
+
+
+/***/ }),
+/* 9 */
+/***/ ((__unused_webpack___webpack_module__, __webpack_exports__, __webpack_require__) => {
+
+__webpack_require__.r(__webpack_exports__);
+/* harmony export */ __webpack_require__.d(__webpack_exports__, {
+/* harmony export */   "ArrayBase": () => (/* binding */ ArrayBase)
+/* harmony export */ });
+class ArrayBase extends Array {
+  constructor({ source, tokens }) {
+    super();
+    Object.defineProperties(this, {
+      source: { value: source },
+      tokens: { value: tokens },
+      parent: { value: null, writable: true },
+    });
+  }
+}
+
+
+/***/ }),
+/* 10 */
+/***/ ((__unused_webpack___webpack_module__, __webpack_exports__, __webpack_require__) => {
+
+__webpack_require__.r(__webpack_exports__);
+/* harmony export */ __webpack_require__.d(__webpack_exports__, {
+/* harmony export */   "Eof": () => (/* binding */ Eof),
+/* harmony export */   "WrappedToken": () => (/* binding */ WrappedToken)
+/* harmony export */ });
+/* harmony import */ var _base_js__WEBPACK_IMPORTED_MODULE_0__ = __webpack_require__(6);
+/* harmony import */ var _helpers_js__WEBPACK_IMPORTED_MODULE_1__ = __webpack_require__(4);
+
+
+
+class WrappedToken extends _base_js__WEBPACK_IMPORTED_MODULE_0__.Base {
+  /**
+   * @param {import("../tokeniser.js").Tokeniser} tokeniser
+   * @param {string} type
+   */
+  static parser(tokeniser, type) {
+    return () => {
+      const value = tokeniser.consumeKind(type);
+      if (value) {
+        return new WrappedToken({
+          source: tokeniser.source,
+          tokens: { value },
+        });
+      }
+    };
+  }
+
+  get value() {
+    return (0,_helpers_js__WEBPACK_IMPORTED_MODULE_1__.unescape)(this.tokens.value.value);
+  }
+
+  /** @param {import("../writer.js").Writer} w */
+  write(w) {
+    return w.ts.wrap([
+      w.token(this.tokens.value),
+      w.token(this.tokens.separator),
+    ]);
+  }
+}
+
+class Eof extends WrappedToken {
+  /**
+   * @param {import("../tokeniser.js").Tokeniser} tokeniser
+   */
+  static parse(tokeniser) {
+    const value = tokeniser.consumeKind("eof");
+    if (value) {
+      return new Eof({ source: tokeniser.source, tokens: { value } });
+    }
+  }
+
+  get type() {
+    return "eof";
+  }
+}
+
+
+/***/ }),
+/* 11 */
+/***/ ((__unused_webpack___webpack_module__, __webpack_exports__, __webpack_require__) => {
+
+__webpack_require__.r(__webpack_exports__);
+/* harmony export */ __webpack_require__.d(__webpack_exports__, {
+/* harmony export */   "Argument": () => (/* binding */ Argument)
+/* harmony export */ });
+/* harmony import */ var _base_js__WEBPACK_IMPORTED_MODULE_0__ = __webpack_require__(6);
+/* harmony import */ var _default_js__WEBPACK_IMPORTED_MODULE_1__ = __webpack_require__(12);
+/* harmony import */ var _extended_attributes_js__WEBPACK_IMPORTED_MODULE_2__ = __webpack_require__(8);
+/* harmony import */ var _helpers_js__WEBPACK_IMPORTED_MODULE_3__ = __webpack_require__(4);
+/* harmony import */ var _tokeniser_js__WEBPACK_IMPORTED_MODULE_4__ = __webpack_require__(2);
+/* harmony import */ var _error_js__WEBPACK_IMPORTED_MODULE_5__ = __webpack_require__(3);
+/* harmony import */ var _validators_helpers_js__WEBPACK_IMPORTED_MODULE_6__ = __webpack_require__(7);
+
+
+
+
+
+
+
+
+class Argument extends _base_js__WEBPACK_IMPORTED_MODULE_0__.Base {
+  /**
+   * @param {import("../tokeniser.js").Tokeniser} tokeniser
+   */
+  static parse(tokeniser) {
+    const start_position = tokeniser.position;
+    /** @type {Base["tokens"]} */
+    const tokens = {};
+    const ret = (0,_helpers_js__WEBPACK_IMPORTED_MODULE_3__.autoParenter)(
+      new Argument({ source: tokeniser.source, tokens })
+    );
+    ret.extAttrs = _extended_attributes_js__WEBPACK_IMPORTED_MODULE_2__.ExtendedAttributes.parse(tokeniser);
+    tokens.optional = tokeniser.consume("optional");
+    ret.idlType = (0,_helpers_js__WEBPACK_IMPORTED_MODULE_3__.type_with_extended_attributes)(tokeniser, "argument-type");
+    if (!ret.idlType) {
+      return tokeniser.unconsume(start_position);
+    }
+    if (!tokens.optional) {
+      tokens.variadic = tokeniser.consume("...");
+    }
+    tokens.name =
+      tokeniser.consumeKind("identifier") ||
+      tokeniser.consume(..._tokeniser_js__WEBPACK_IMPORTED_MODULE_4__.argumentNameKeywords);
+    if (!tokens.name) {
+      return tokeniser.unconsume(start_position);
+    }
+    ret.default = tokens.optional ? _default_js__WEBPACK_IMPORTED_MODULE_1__.Default.parse(tokeniser) : null;
+    return ret.this;
+  }
+
+  get type() {
+    return "argument";
+  }
+  get optional() {
+    return !!this.tokens.optional;
+  }
+  get variadic() {
+    return !!this.tokens.variadic;
+  }
+  get name() {
+    return (0,_helpers_js__WEBPACK_IMPORTED_MODULE_3__.unescape)(this.tokens.name.value);
+  }
+
+  /**
+   * @param {import("../validator.js").Definitions} defs
+   */
+  *validate(defs) {
+    yield* this.extAttrs.validate(defs);
+    yield* this.idlType.validate(defs);
+    const result = (0,_validators_helpers_js__WEBPACK_IMPORTED_MODULE_6__.idlTypeIncludesDictionary)(this.idlType, defs, {
+      useNullableInner: true,
+    });
+    if (result) {
+      if (this.idlType.nullable) {
+        const message = `Dictionary arguments cannot be nullable.`;
+        yield (0,_error_js__WEBPACK_IMPORTED_MODULE_5__.validationError)(
+          this.tokens.name,
+          this,
+          "no-nullable-dict-arg",
+          message
+        );
+      } else if (!this.optional) {
+        if (
+          this.parent &&
+          !(0,_validators_helpers_js__WEBPACK_IMPORTED_MODULE_6__.dictionaryIncludesRequiredField)(result.dictionary, defs) &&
+          isLastRequiredArgument(this)
+        ) {
+          const message = `Dictionary argument must be optional if it has no required fields`;
+          yield (0,_error_js__WEBPACK_IMPORTED_MODULE_5__.validationError)(
+            this.tokens.name,
+            this,
+            "dict-arg-optional",
+            message,
+            {
+              autofix: autofixDictionaryArgumentOptionality(this),
+            }
+          );
+        }
+      } else if (!this.default) {
+        const message = `Optional dictionary arguments must have a default value of \`{}\`.`;
+        yield (0,_error_js__WEBPACK_IMPORTED_MODULE_5__.validationError)(
+          this.tokens.name,
+          this,
+          "dict-arg-default",
+          message,
+          {
+            autofix: autofixOptionalDictionaryDefaultValue(this),
+          }
+        );
+      }
+    }
+  }
+
+  /** @param {import("../writer.js").Writer} w */
+  write(w) {
+    return w.ts.wrap([
+      this.extAttrs.write(w),
+      w.token(this.tokens.optional),
+      w.ts.type(this.idlType.write(w)),
+      w.token(this.tokens.variadic),
+      w.name_token(this.tokens.name, { data: this }),
+      this.default ? this.default.write(w) : "",
+      w.token(this.tokens.separator),
+    ]);
+  }
+}
+
+/**
+ * @param {Argument} arg
+ */
+function isLastRequiredArgument(arg) {
+  const list = arg.parent.arguments || arg.parent.list;
+  const index = list.indexOf(arg);
+  const requiredExists = list.slice(index + 1).some((a) => !a.optional);
+  return !requiredExists;
+}
+
+/**
+ * @param {Argument} arg
+ */
+function autofixDictionaryArgumentOptionality(arg) {
+  return () => {
+    const firstToken = (0,_helpers_js__WEBPACK_IMPORTED_MODULE_3__.getFirstToken)(arg.idlType);
+    arg.tokens.optional = {
+      ...firstToken,
+      type: "optional",
+      value: "optional",
+    };
+    firstToken.trivia = " ";
+    autofixOptionalDictionaryDefaultValue(arg)();
+  };
+}
+
+/**
+ * @param {Argument} arg
+ */
+function autofixOptionalDictionaryDefaultValue(arg) {
+  return () => {
+    arg.default = _default_js__WEBPACK_IMPORTED_MODULE_1__.Default.parse(new _tokeniser_js__WEBPACK_IMPORTED_MODULE_4__.Tokeniser(" = {}"));
+  };
+}
+
+
+/***/ }),
+/* 12 */
+/***/ ((__unused_webpack___webpack_module__, __webpack_exports__, __webpack_require__) => {
+
+__webpack_require__.r(__webpack_exports__);
+/* harmony export */ __webpack_require__.d(__webpack_exports__, {
+/* harmony export */   "Default": () => (/* binding */ Default)
+/* harmony export */ });
+/* harmony import */ var _base_js__WEBPACK_IMPORTED_MODULE_0__ = __webpack_require__(6);
+/* harmony import */ var _helpers_js__WEBPACK_IMPORTED_MODULE_1__ = __webpack_require__(4);
+
+
+
+class Default extends _base_js__WEBPACK_IMPORTED_MODULE_0__.Base {
+  /**
+   * @param {import("../tokeniser.js").Tokeniser} tokeniser
+   */
+  static parse(tokeniser) {
+    const assign = tokeniser.consume("=");
+    if (!assign) {
+      return null;
+    }
+    const def =
+      (0,_helpers_js__WEBPACK_IMPORTED_MODULE_1__.const_value)(tokeniser) ||
+      tokeniser.consumeKind("string") ||
+      tokeniser.consume("null", "[", "{") ||
+      tokeniser.error("No value for default");
+    const expression = [def];
+    if (def.value === "[") {
+      const close =
+        tokeniser.consume("]") ||
+        tokeniser.error("Default sequence value must be empty");
+      expression.push(close);
+    } else if (def.value === "{") {
+      const close =
+        tokeniser.consume("}") ||
+        tokeniser.error("Default dictionary value must be empty");
+      expression.push(close);
+    }
+    return new Default({
+      source: tokeniser.source,
+      tokens: { assign },
+      expression,
+    });
+  }
+
+  constructor({ source, tokens, expression }) {
+    super({ source, tokens });
+    expression.parent = this;
+    Object.defineProperty(this, "expression", { value: expression });
+  }
+
+  get type() {
+    return (0,_helpers_js__WEBPACK_IMPORTED_MODULE_1__.const_data)(this.expression[0]).type;
+  }
+  get value() {
+    return (0,_helpers_js__WEBPACK_IMPORTED_MODULE_1__.const_data)(this.expression[0]).value;
+  }
+  get negative() {
+    return (0,_helpers_js__WEBPACK_IMPORTED_MODULE_1__.const_data)(this.expression[0]).negative;
+  }
+
+  /** @param {import("../writer.js").Writer} w */
+  write(w) {
+    return w.ts.wrap([
+      w.token(this.tokens.assign),
+      ...this.expression.map((t) => w.token(t)),
+    ]);
+  }
+}
+
+
+/***/ }),
+/* 13 */
+/***/ ((__unused_webpack___webpack_module__, __webpack_exports__, __webpack_require__) => {
+
+__webpack_require__.r(__webpack_exports__);
+/* harmony export */ __webpack_require__.d(__webpack_exports__, {
+/* harmony export */   "Operation": () => (/* binding */ Operation)
+/* harmony export */ });
+/* harmony import */ var _base_js__WEBPACK_IMPORTED_MODULE_0__ = __webpack_require__(6);
+/* harmony import */ var _helpers_js__WEBPACK_IMPORTED_MODULE_1__ = __webpack_require__(4);
+/* harmony import */ var _error_js__WEBPACK_IMPORTED_MODULE_2__ = __webpack_require__(3);
+
+
+
+
+class Operation extends _base_js__WEBPACK_IMPORTED_MODULE_0__.Base {
+  /**
+   * @typedef {import("../tokeniser.js").Token} Token
+   *
+   * @param {import("../tokeniser.js").Tokeniser} tokeniser
+   * @param {object} [options]
+   * @param {Token} [options.special]
+   * @param {Token} [options.regular]
+   */
+  static parse(tokeniser, { special, regular } = {}) {
+    const tokens = { special };
+    const ret = (0,_helpers_js__WEBPACK_IMPORTED_MODULE_1__.autoParenter)(
+      new Operation({ source: tokeniser.source, tokens })
+    );
+    if (special && special.value === "stringifier") {
+      tokens.termination = tokeniser.consume(";");
+      if (tokens.termination) {
+        ret.arguments = [];
+        return ret;
+      }
+    }
+    if (!special && !regular) {
+      tokens.special = tokeniser.consume("getter", "setter", "deleter");
+    }
+    ret.idlType =
+      (0,_helpers_js__WEBPACK_IMPORTED_MODULE_1__.return_type)(tokeniser) || tokeniser.error("Missing return type");
+    tokens.name =
+      tokeniser.consumeKind("identifier") || tokeniser.consume("includes");
+    tokens.open =
+      tokeniser.consume("(") || tokeniser.error("Invalid operation");
+    ret.arguments = (0,_helpers_js__WEBPACK_IMPORTED_MODULE_1__.argument_list)(tokeniser);
+    tokens.close =
+      tokeniser.consume(")") || tokeniser.error("Unterminated operation");
+    tokens.termination =
+      tokeniser.consume(";") ||
+      tokeniser.error("Unterminated operation, expected `;`");
+    return ret.this;
+  }
+
+  get type() {
+    return "operation";
+  }
+  get name() {
+    const { name } = this.tokens;
+    if (!name) {
+      return "";
+    }
+    return (0,_helpers_js__WEBPACK_IMPORTED_MODULE_1__.unescape)(name.value);
+  }
+  get special() {
+    if (!this.tokens.special) {
+      return "";
+    }
+    return this.tokens.special.value;
+  }
+
+  *validate(defs) {
+    yield* this.extAttrs.validate(defs);
+    if (!this.name && ["", "static"].includes(this.special)) {
+      const message = `Regular or static operations must have both a return type and an identifier.`;
+      yield (0,_error_js__WEBPACK_IMPORTED_MODULE_2__.validationError)(this.tokens.open, this, "incomplete-op", message);
+    }
+    if (this.idlType) {
+      yield* this.idlType.validate(defs);
+    }
+    for (const argument of this.arguments) {
+      yield* argument.validate(defs);
+    }
+  }
+
+  /** @param {import("../writer.js").Writer} w */
+  write(w) {
+    const { parent } = this;
+    const body = this.idlType
+      ? [
+          w.ts.type(this.idlType.write(w)),
+          w.name_token(this.tokens.name, { data: this, parent }),
+          w.token(this.tokens.open),
+          w.ts.wrap(this.arguments.map((arg) => arg.write(w))),
+          w.token(this.tokens.close),
+        ]
+      : [];
+    return w.ts.definition(
+      w.ts.wrap([
+        this.extAttrs.write(w),
+        this.tokens.name
+          ? w.token(this.tokens.special)
+          : w.token(this.tokens.special, w.ts.nameless, { data: this, parent }),
+        ...body,
+        w.token(this.tokens.termination),
+      ]),
+      { data: this, parent }
+    );
+  }
+}
+
+
+/***/ }),
+/* 14 */
+/***/ ((__unused_webpack___webpack_module__, __webpack_exports__, __webpack_require__) => {
+
+__webpack_require__.r(__webpack_exports__);
+/* harmony export */ __webpack_require__.d(__webpack_exports__, {
+/* harmony export */   "Attribute": () => (/* binding */ Attribute)
+/* harmony export */ });
+/* harmony import */ var _error_js__WEBPACK_IMPORTED_MODULE_0__ = __webpack_require__(3);
+/* harmony import */ var _validators_helpers_js__WEBPACK_IMPORTED_MODULE_1__ = __webpack_require__(7);
+/* harmony import */ var _base_js__WEBPACK_IMPORTED_MODULE_2__ = __webpack_require__(6);
+/* harmony import */ var _helpers_js__WEBPACK_IMPORTED_MODULE_3__ = __webpack_require__(4);
+
+
+
+
+
+class Attribute extends _base_js__WEBPACK_IMPORTED_MODULE_2__.Base {
+  /**
+   * @param {import("../tokeniser.js").Tokeniser} tokeniser
+   * @param {object} [options]
+   * @param {import("../tokeniser.js").Token} [options.special]
+   * @param {boolean} [options.noInherit]
+   * @param {boolean} [options.readonly]
+   */
+  static parse(
+    tokeniser,
+    { special, noInherit = false, readonly = false } = {}
+  ) {
+    const start_position = tokeniser.position;
+    const tokens = { special };
+    const ret = (0,_helpers_js__WEBPACK_IMPORTED_MODULE_3__.autoParenter)(
+      new Attribute({ source: tokeniser.source, tokens })
+    );
+    if (!special && !noInherit) {
+      tokens.special = tokeniser.consume("inherit");
+    }
+    if (ret.special === "inherit" && tokeniser.probe("readonly")) {
+      tokeniser.error("Inherited attributes cannot be read-only");
+    }
+    tokens.readonly = tokeniser.consume("readonly");
+    if (readonly && !tokens.readonly && tokeniser.probe("attribute")) {
+      tokeniser.error("Attributes must be readonly in this context");
+    }
+    tokens.base = tokeniser.consume("attribute");
+    if (!tokens.base) {
+      tokeniser.unconsume(start_position);
+      return;
+    }
+    ret.idlType =
+      (0,_helpers_js__WEBPACK_IMPORTED_MODULE_3__.type_with_extended_attributes)(tokeniser, "attribute-type") ||
+      tokeniser.error("Attribute lacks a type");
+    tokens.name =
+      tokeniser.consumeKind("identifier") ||
+      tokeniser.consume("async", "required") ||
+      tokeniser.error("Attribute lacks a name");
+    tokens.termination =
+      tokeniser.consume(";") ||
+      tokeniser.error("Unterminated attribute, expected `;`");
+    return ret.this;
+  }
+
+  get type() {
+    return "attribute";
+  }
+  get special() {
+    if (!this.tokens.special) {
+      return "";
+    }
+    return this.tokens.special.value;
+  }
+  get readonly() {
+    return !!this.tokens.readonly;
+  }
+  get name() {
+    return (0,_helpers_js__WEBPACK_IMPORTED_MODULE_3__.unescape)(this.tokens.name.value);
+  }
+
+  *validate(defs) {
+    yield* this.extAttrs.validate(defs);
+    yield* this.idlType.validate(defs);
+
+    switch (this.idlType.generic) {
+      case "sequence":
+      case "record": {
+        const message = `Attributes cannot accept ${this.idlType.generic} types.`;
+        yield (0,_error_js__WEBPACK_IMPORTED_MODULE_0__.validationError)(
+          this.tokens.name,
+          this,
+          "attr-invalid-type",
+          message
+        );
+        break;
+      }
+      default: {
+        const { reference } =
+          (0,_validators_helpers_js__WEBPACK_IMPORTED_MODULE_1__.idlTypeIncludesDictionary)(this.idlType, defs) || {};
+        if (reference) {
+          const targetToken = (this.idlType.union ? reference : this.idlType)
+            .tokens.base;
+          const message = "Attributes cannot accept dictionary types.";
+          yield (0,_error_js__WEBPACK_IMPORTED_MODULE_0__.validationError)(
+            targetToken,
+            this,
+            "attr-invalid-type",
+            message
+          );
+        }
+      }
+    }
+  }
+
+  /** @param {import("../writer.js").Writer} w */
+  write(w) {
+    const { parent } = this;
+    return w.ts.definition(
+      w.ts.wrap([
+        this.extAttrs.write(w),
+        w.token(this.tokens.special),
+        w.token(this.tokens.readonly),
+        w.token(this.tokens.base),
+        w.ts.type(this.idlType.write(w)),
+        w.name_token(this.tokens.name, { data: this, parent }),
+        w.token(this.tokens.termination),
+      ]),
+      { data: this, parent }
+    );
+  }
+}
+
+
+/***/ }),
+/* 15 */
+/***/ ((__unused_webpack___webpack_module__, __webpack_exports__, __webpack_require__) => {
+
+__webpack_require__.r(__webpack_exports__);
+/* harmony export */ __webpack_require__.d(__webpack_exports__, {
+/* harmony export */   "Enum": () => (/* binding */ Enum),
+/* harmony export */   "EnumValue": () => (/* binding */ EnumValue)
+/* harmony export */ });
+/* harmony import */ var _helpers_js__WEBPACK_IMPORTED_MODULE_0__ = __webpack_require__(4);
+/* harmony import */ var _token_js__WEBPACK_IMPORTED_MODULE_1__ = __webpack_require__(10);
+/* harmony import */ var _base_js__WEBPACK_IMPORTED_MODULE_2__ = __webpack_require__(6);
+
+
+
+
+class EnumValue extends _token_js__WEBPACK_IMPORTED_MODULE_1__.WrappedToken {
+  /**
+   * @param {import("../tokeniser.js").Tokeniser} tokeniser
+   */
+  static parse(tokeniser) {
+    const value = tokeniser.consumeKind("string");
+    if (value) {
+      return new EnumValue({ source: tokeniser.source, tokens: { value } });
+    }
+  }
+
+  get type() {
+    return "enum-value";
+  }
+  get value() {
+    return super.value.slice(1, -1);
+  }
+
+  /** @param {import("../writer.js").Writer} w */
+  write(w) {
+    const { parent } = this;
+    return w.ts.wrap([
+      w.ts.trivia(this.tokens.value.trivia),
+      w.ts.definition(
+        w.ts.wrap(['"', w.ts.name(this.value, { data: this, parent }), '"']),
+        { data: this, parent }
+      ),
+      w.token(this.tokens.separator),
+    ]);
+  }
+}
+
+class Enum extends _base_js__WEBPACK_IMPORTED_MODULE_2__.Base {
+  /**
+   * @param {import("../tokeniser.js").Tokeniser} tokeniser
+   */
+  static parse(tokeniser) {
+    /** @type {Base["tokens"]} */
+    const tokens = {};
+    tokens.base = tokeniser.consume("enum");
+    if (!tokens.base) {
+      return;
+    }
+    tokens.name =
+      tokeniser.consumeKind("identifier") ||
+      tokeniser.error("No name for enum");
+    const ret = (0,_helpers_js__WEBPACK_IMPORTED_MODULE_0__.autoParenter)(new Enum({ source: tokeniser.source, tokens }));
+    tokeniser.current = ret.this;
+    tokens.open = tokeniser.consume("{") || tokeniser.error("Bodyless enum");
+    ret.values = (0,_helpers_js__WEBPACK_IMPORTED_MODULE_0__.list)(tokeniser, {
+      parser: EnumValue.parse,
+      allowDangler: true,
+      listName: "enumeration",
+    });
+    if (tokeniser.probeKind("string")) {
+      tokeniser.error("No comma between enum values");
+    }
+    tokens.close =
+      tokeniser.consume("}") || tokeniser.error("Unexpected value in enum");
+    if (!ret.values.length) {
+      tokeniser.error("No value in enum");
+    }
+    tokens.termination =
+      tokeniser.consume(";") || tokeniser.error("No semicolon after enum");
+    return ret.this;
+  }
+
+  get type() {
+    return "enum";
+  }
+  get name() {
+    return (0,_helpers_js__WEBPACK_IMPORTED_MODULE_0__.unescape)(this.tokens.name.value);
+  }
+
+  /** @param {import("../writer.js").Writer} w */
+  write(w) {
+    return w.ts.definition(
+      w.ts.wrap([
+        this.extAttrs.write(w),
+        w.token(this.tokens.base),
+        w.name_token(this.tokens.name, { data: this }),
+        w.token(this.tokens.open),
+        w.ts.wrap(this.values.map((v) => v.write(w))),
+        w.token(this.tokens.close),
+        w.token(this.tokens.termination),
+      ]),
+      { data: this }
+    );
+  }
+}
+
+
+/***/ }),
+/* 16 */
+/***/ ((__unused_webpack___webpack_module__, __webpack_exports__, __webpack_require__) => {
+
+__webpack_require__.r(__webpack_exports__);
+/* harmony export */ __webpack_require__.d(__webpack_exports__, {
+/* harmony export */   "Includes": () => (/* binding */ Includes)
+/* harmony export */ });
+/* harmony import */ var _base_js__WEBPACK_IMPORTED_MODULE_0__ = __webpack_require__(6);
+/* harmony import */ var _helpers_js__WEBPACK_IMPORTED_MODULE_1__ = __webpack_require__(4);
+
+
+
+class Includes extends _base_js__WEBPACK_IMPORTED_MODULE_0__.Base {
+  /**
+   * @param {import("../tokeniser.js").Tokeniser} tokeniser
+   */
+  static parse(tokeniser) {
+    const target = tokeniser.consumeKind("identifier");
+    if (!target) {
+      return;
+    }
+    const tokens = { target };
+    tokens.includes = tokeniser.consume("includes");
+    if (!tokens.includes) {
+      tokeniser.unconsume(target.index);
+      return;
+    }
+    tokens.mixin =
+      tokeniser.consumeKind("identifier") ||
+      tokeniser.error("Incomplete includes statement");
+    tokens.termination =
+      tokeniser.consume(";") ||
+      tokeniser.error("No terminating ; for includes statement");
+    return new Includes({ source: tokeniser.source, tokens });
+  }
+
+  get type() {
+    return "includes";
+  }
+  get target() {
+    return (0,_helpers_js__WEBPACK_IMPORTED_MODULE_1__.unescape)(this.tokens.target.value);
+  }
+  get includes() {
+    return (0,_helpers_js__WEBPACK_IMPORTED_MODULE_1__.unescape)(this.tokens.mixin.value);
+  }
+
+  /** @param {import("../writer.js").Writer} w */
+  write(w) {
+    return w.ts.definition(
+      w.ts.wrap([
+        this.extAttrs.write(w),
+        w.reference_token(this.tokens.target, this),
+        w.token(this.tokens.includes),
+        w.reference_token(this.tokens.mixin, this),
+        w.token(this.tokens.termination),
+      ]),
+      { data: this }
+    );
+  }
+}
+
+
+/***/ }),
+/* 17 */
+/***/ ((__unused_webpack___webpack_module__, __webpack_exports__, __webpack_require__) => {
+
+__webpack_require__.r(__webpack_exports__);
+/* harmony export */ __webpack_require__.d(__webpack_exports__, {
+/* harmony export */   "Typedef": () => (/* binding */ Typedef)
+/* harmony export */ });
+/* harmony import */ var _base_js__WEBPACK_IMPORTED_MODULE_0__ = __webpack_require__(6);
+/* harmony import */ var _helpers_js__WEBPACK_IMPORTED_MODULE_1__ = __webpack_require__(4);
+
+
+
+class Typedef extends _base_js__WEBPACK_IMPORTED_MODULE_0__.Base {
+  /**
+   * @param {import("../tokeniser.js").Tokeniser} tokeniser
+   */
+  static parse(tokeniser) {
+    /** @type {Base["tokens"]} */
+    const tokens = {};
+    const ret = (0,_helpers_js__WEBPACK_IMPORTED_MODULE_1__.autoParenter)(new Typedef({ source: tokeniser.source, tokens }));
+    tokens.base = tokeniser.consume("typedef");
+    if (!tokens.base) {
+      return;
+    }
+    ret.idlType =
+      (0,_helpers_js__WEBPACK_IMPORTED_MODULE_1__.type_with_extended_attributes)(tokeniser, "typedef-type") ||
+      tokeniser.error("Typedef lacks a type");
+    tokens.name =
+      tokeniser.consumeKind("identifier") ||
+      tokeniser.error("Typedef lacks a name");
+    tokeniser.current = ret.this;
+    tokens.termination =
+      tokeniser.consume(";") ||
+      tokeniser.error("Unterminated typedef, expected `;`");
+    return ret.this;
+  }
+
+  get type() {
+    return "typedef";
+  }
+  get name() {
+    return (0,_helpers_js__WEBPACK_IMPORTED_MODULE_1__.unescape)(this.tokens.name.value);
+  }
+
+  *validate(defs) {
+    yield* this.idlType.validate(defs);
+  }
+
+  /** @param {import("../writer.js").Writer} w */
+  write(w) {
+    return w.ts.definition(
+      w.ts.wrap([
+        this.extAttrs.write(w),
+        w.token(this.tokens.base),
+        w.ts.type(this.idlType.write(w)),
+        w.name_token(this.tokens.name, { data: this }),
+        w.token(this.tokens.termination),
+      ]),
+      { data: this }
+    );
+  }
+}
+
+
+/***/ }),
+/* 18 */
+/***/ ((__unused_webpack___webpack_module__, __webpack_exports__, __webpack_require__) => {
+
+__webpack_require__.r(__webpack_exports__);
+/* harmony export */ __webpack_require__.d(__webpack_exports__, {
+/* harmony export */   "CallbackFunction": () => (/* binding */ CallbackFunction)
+/* harmony export */ });
+/* harmony import */ var _base_js__WEBPACK_IMPORTED_MODULE_0__ = __webpack_require__(6);
+/* harmony import */ var _helpers_js__WEBPACK_IMPORTED_MODULE_1__ = __webpack_require__(4);
+
+
+
+class CallbackFunction extends _base_js__WEBPACK_IMPORTED_MODULE_0__.Base {
+  /**
+   * @param {import("../tokeniser.js").Tokeniser} tokeniser
+   */
+  static parse(tokeniser, base) {
+    const tokens = { base };
+    const ret = (0,_helpers_js__WEBPACK_IMPORTED_MODULE_1__.autoParenter)(
+      new CallbackFunction({ source: tokeniser.source, tokens })
+    );
+    tokens.name =
+      tokeniser.consumeKind("identifier") ||
+      tokeniser.error("Callback lacks a name");
+    tokeniser.current = ret.this;
+    tokens.assign =
+      tokeniser.consume("=") || tokeniser.error("Callback lacks an assignment");
+    ret.idlType =
+      (0,_helpers_js__WEBPACK_IMPORTED_MODULE_1__.return_type)(tokeniser) || tokeniser.error("Callback lacks a return type");
+    tokens.open =
+      tokeniser.consume("(") ||
+      tokeniser.error("Callback lacks parentheses for arguments");
+    ret.arguments = (0,_helpers_js__WEBPACK_IMPORTED_MODULE_1__.argument_list)(tokeniser);
+    tokens.close =
+      tokeniser.consume(")") || tokeniser.error("Unterminated callback");
+    tokens.termination =
+      tokeniser.consume(";") ||
+      tokeniser.error("Unterminated callback, expected `;`");
+    return ret.this;
+  }
+
+  get type() {
+    return "callback";
+  }
+  get name() {
+    return (0,_helpers_js__WEBPACK_IMPORTED_MODULE_1__.unescape)(this.tokens.name.value);
+  }
+
+  *validate(defs) {
+    yield* this.extAttrs.validate(defs);
+    yield* this.idlType.validate(defs);
+  }
+
+  /** @param {import("../writer.js").Writer} w */
+  write(w) {
+    return w.ts.definition(
+      w.ts.wrap([
+        this.extAttrs.write(w),
+        w.token(this.tokens.base),
+        w.name_token(this.tokens.name, { data: this }),
+        w.token(this.tokens.assign),
+        w.ts.type(this.idlType.write(w)),
+        w.token(this.tokens.open),
+        ...this.arguments.map((arg) => arg.write(w)),
+        w.token(this.tokens.close),
+        w.token(this.tokens.termination),
+      ]),
+      { data: this }
+    );
+  }
+}
+
+
+/***/ }),
+/* 19 */
+/***/ ((__unused_webpack___webpack_module__, __webpack_exports__, __webpack_require__) => {
+
+__webpack_require__.r(__webpack_exports__);
+/* harmony export */ __webpack_require__.d(__webpack_exports__, {
+/* harmony export */   "Interface": () => (/* binding */ Interface)
+/* harmony export */ });
+/* harmony import */ var _container_js__WEBPACK_IMPORTED_MODULE_0__ = __webpack_require__(20);
+/* harmony import */ var _attribute_js__WEBPACK_IMPORTED_MODULE_1__ = __webpack_require__(14);
+/* harmony import */ var _operation_js__WEBPACK_IMPORTED_MODULE_2__ = __webpack_require__(13);
+/* harmony import */ var _constant_js__WEBPACK_IMPORTED_MODULE_3__ = __webpack_require__(21);
+/* harmony import */ var _iterable_js__WEBPACK_IMPORTED_MODULE_4__ = __webpack_require__(22);
+/* harmony import */ var _helpers_js__WEBPACK_IMPORTED_MODULE_5__ = __webpack_require__(4);
+/* harmony import */ var _error_js__WEBPACK_IMPORTED_MODULE_6__ = __webpack_require__(3);
+/* harmony import */ var _validators_interface_js__WEBPACK_IMPORTED_MODULE_7__ = __webpack_require__(23);
+/* harmony import */ var _constructor_js__WEBPACK_IMPORTED_MODULE_8__ = __webpack_require__(24);
+/* harmony import */ var _tokeniser_js__WEBPACK_IMPORTED_MODULE_9__ = __webpack_require__(2);
+/* harmony import */ var _extended_attributes_js__WEBPACK_IMPORTED_MODULE_10__ = __webpack_require__(8);
+
+
+
+
+
+
+
+
+
+
+
+
+/**
+ * @param {import("../tokeniser.js").Tokeniser} tokeniser
+ */
+function static_member(tokeniser) {
+  const special = tokeniser.consume("static");
+  if (!special) return;
+  const member =
+    _attribute_js__WEBPACK_IMPORTED_MODULE_1__.Attribute.parse(tokeniser, { special }) ||
+    _operation_js__WEBPACK_IMPORTED_MODULE_2__.Operation.parse(tokeniser, { special }) ||
+    tokeniser.error("No body in static member");
+  return member;
+}
+
+class Interface extends _container_js__WEBPACK_IMPORTED_MODULE_0__.Container {
+  /**
+   * @param {import("../tokeniser.js").Tokeniser} tokeniser
+   */
+  static parse(tokeniser, base, { partial = null } = {}) {
+    const tokens = { partial, base };
+    return _container_js__WEBPACK_IMPORTED_MODULE_0__.Container.parse(
+      tokeniser,
+      new Interface({ source: tokeniser.source, tokens }),
+      {
+        inheritable: !partial,
+        allowedMembers: [
+          [_constant_js__WEBPACK_IMPORTED_MODULE_3__.Constant.parse],
+          [_constructor_js__WEBPACK_IMPORTED_MODULE_8__.Constructor.parse],
+          [static_member],
+          [_helpers_js__WEBPACK_IMPORTED_MODULE_5__.stringifier],
+          [_iterable_js__WEBPACK_IMPORTED_MODULE_4__.IterableLike.parse],
+          [_attribute_js__WEBPACK_IMPORTED_MODULE_1__.Attribute.parse],
+          [_operation_js__WEBPACK_IMPORTED_MODULE_2__.Operation.parse],
+        ],
+      }
+    );
+  }
+
+  get type() {
+    return "interface";
+  }
+
+  *validate(defs) {
+    yield* this.extAttrs.validate(defs);
+    if (
+      !this.partial &&
+      this.extAttrs.every((extAttr) => extAttr.name !== "Exposed")
+    ) {
+      const message = `Interfaces must have \`[Exposed]\` extended attribute. \
+To fix, add, for example, \`[Exposed=Window]\`. Please also consider carefully \
+if your interface should also be exposed in a Worker scope. Refer to the \
+[WebIDL spec section on Exposed](https://heycam.github.io/webidl/#Exposed) \
+for more information.`;
+      yield (0,_error_js__WEBPACK_IMPORTED_MODULE_6__.validationError)(
+        this.tokens.name,
+        this,
+        "require-exposed",
+        message,
+        {
+          autofix: (0,_helpers_js__WEBPACK_IMPORTED_MODULE_5__.autofixAddExposedWindow)(this),
+        }
+      );
+    }
+    const oldConstructors = this.extAttrs.filter(
+      (extAttr) => extAttr.name === "Constructor"
+    );
+    for (const constructor of oldConstructors) {
+      const message = `Constructors should now be represented as a \`constructor()\` operation on the interface \
+instead of \`[Constructor]\` extended attribute. Refer to the \
+[WebIDL spec section on constructor operations](https://heycam.github.io/webidl/#idl-constructors) \
+for more information.`;
+      yield (0,_error_js__WEBPACK_IMPORTED_MODULE_6__.validationError)(
+        constructor.tokens.name,
+        this,
+        "constructor-member",
+        message,
+        {
+          autofix: autofixConstructor(this, constructor),
+        }
+      );
+    }
+
+    const isGlobal = this.extAttrs.some((extAttr) => extAttr.name === "Global");
+    if (isGlobal) {
+      const factoryFunctions = this.extAttrs.filter(
+        (extAttr) => extAttr.name === "LegacyFactoryFunction"
+      );
+      for (const named of factoryFunctions) {
+        const message = `Interfaces marked as \`[Global]\` cannot have factory functions.`;
+        yield (0,_error_js__WEBPACK_IMPORTED_MODULE_6__.validationError)(
+          named.tokens.name,
+          this,
+          "no-constructible-global",
+          message
+        );
+      }
+
+      const constructors = this.members.filter(
+        (member) => member.type === "constructor"
+      );
+      for (const named of constructors) {
+        const message = `Interfaces marked as \`[Global]\` cannot have constructors.`;
+        yield (0,_error_js__WEBPACK_IMPORTED_MODULE_6__.validationError)(
+          named.tokens.base,
+          this,
+          "no-constructible-global",
+          message
+        );
+      }
+    }
+
+    yield* super.validate(defs);
+    if (!this.partial) {
+      yield* (0,_validators_interface_js__WEBPACK_IMPORTED_MODULE_7__.checkInterfaceMemberDuplication)(defs, this);
+    }
+  }
+}
+
+function autofixConstructor(interfaceDef, constructorExtAttr) {
+  interfaceDef = (0,_helpers_js__WEBPACK_IMPORTED_MODULE_5__.autoParenter)(interfaceDef);
+  return () => {
+    const indentation = (0,_helpers_js__WEBPACK_IMPORTED_MODULE_5__.getLastIndentation)(
+      interfaceDef.extAttrs.tokens.open.trivia
+    );
+    const memberIndent = interfaceDef.members.length
+      ? (0,_helpers_js__WEBPACK_IMPORTED_MODULE_5__.getLastIndentation)((0,_helpers_js__WEBPACK_IMPORTED_MODULE_5__.getFirstToken)(interfaceDef.members[0]).trivia)
+      : (0,_helpers_js__WEBPACK_IMPORTED_MODULE_5__.getMemberIndentation)(indentation);
+    const constructorOp = _constructor_js__WEBPACK_IMPORTED_MODULE_8__.Constructor.parse(
+      new _tokeniser_js__WEBPACK_IMPORTED_MODULE_9__.Tokeniser(`\n${memberIndent}constructor();`)
+    );
+    constructorOp.extAttrs = new _extended_attributes_js__WEBPACK_IMPORTED_MODULE_10__.ExtendedAttributes({
+      source: interfaceDef.source,
+      tokens: {},
+    });
+    (0,_helpers_js__WEBPACK_IMPORTED_MODULE_5__.autoParenter)(constructorOp).arguments = constructorExtAttr.arguments;
+
+    const existingIndex = (0,_helpers_js__WEBPACK_IMPORTED_MODULE_5__.findLastIndex)(
+      interfaceDef.members,
+      (m) => m.type === "constructor"
+    );
+    interfaceDef.members.splice(existingIndex + 1, 0, constructorOp);
+
+    const { close } = interfaceDef.tokens;
+    if (!close.trivia.includes("\n")) {
+      close.trivia += `\n${indentation}`;
+    }
+
+    const { extAttrs } = interfaceDef;
+    const index = extAttrs.indexOf(constructorExtAttr);
+    const removed = extAttrs.splice(index, 1);
+    if (!extAttrs.length) {
+      extAttrs.tokens.open = extAttrs.tokens.close = undefined;
+    } else if (extAttrs.length === index) {
+      extAttrs[index - 1].tokens.separator = undefined;
+    } else if (!extAttrs[index].tokens.name.trivia.trim()) {
+      extAttrs[index].tokens.name.trivia = removed[0].tokens.name.trivia;
+    }
+  };
+}
+
+
+/***/ }),
+/* 20 */
+/***/ ((__unused_webpack___webpack_module__, __webpack_exports__, __webpack_require__) => {
+
+__webpack_require__.r(__webpack_exports__);
+/* harmony export */ __webpack_require__.d(__webpack_exports__, {
+/* harmony export */   "Container": () => (/* binding */ Container)
+/* harmony export */ });
+/* harmony import */ var _base_js__WEBPACK_IMPORTED_MODULE_0__ = __webpack_require__(6);
+/* harmony import */ var _extended_attributes_js__WEBPACK_IMPORTED_MODULE_1__ = __webpack_require__(8);
+/* harmony import */ var _helpers_js__WEBPACK_IMPORTED_MODULE_2__ = __webpack_require__(4);
+
+
+
+
+/**
+ * @param {import("../tokeniser.js").Tokeniser} tokeniser
+ */
+function inheritance(tokeniser) {
+  const colon = tokeniser.consume(":");
+  if (!colon) {
+    return {};
+  }
+  const inheritance =
+    tokeniser.consumeKind("identifier") ||
+    tokeniser.error("Inheritance lacks a type");
+  return { colon, inheritance };
+}
+
+class Container extends _base_js__WEBPACK_IMPORTED_MODULE_0__.Base {
+  /**
+   * @param {import("../tokeniser.js").Tokeniser} tokeniser
+   * @param {*} instance TODO: This should be {T extends Container}, but see https://github.com/microsoft/TypeScript/issues/4628
+   * @param {*} args
+   */
+  static parse(tokeniser, instance, { inheritable, allowedMembers }) {
+    const { tokens, type } = instance;
+    tokens.name =
+      tokeniser.consumeKind("identifier") ||
+      tokeniser.error(`Missing name in ${type}`);
+    tokeniser.current = instance;
+    instance = (0,_helpers_js__WEBPACK_IMPORTED_MODULE_2__.autoParenter)(instance);
+    if (inheritable) {
+      Object.assign(tokens, inheritance(tokeniser));
+    }
+    tokens.open = tokeniser.consume("{") || tokeniser.error(`Bodyless ${type}`);
+    instance.members = [];
+    while (true) {
+      tokens.close = tokeniser.consume("}");
+      if (tokens.close) {
+        tokens.termination =
+          tokeniser.consume(";") ||
+          tokeniser.error(`Missing semicolon after ${type}`);
+        return instance.this;
+      }
+      const ea = _extended_attributes_js__WEBPACK_IMPORTED_MODULE_1__.ExtendedAttributes.parse(tokeniser);
+      let mem;
+      for (const [parser, ...args] of allowedMembers) {
+        mem = (0,_helpers_js__WEBPACK_IMPORTED_MODULE_2__.autoParenter)(parser(tokeniser, ...args));
+        if (mem) {
+          break;
+        }
+      }
+      if (!mem) {
+        tokeniser.error("Unknown member");
+      }
+      mem.extAttrs = ea;
+      instance.members.push(mem.this);
+    }
+  }
+
+  get partial() {
+    return !!this.tokens.partial;
+  }
+  get name() {
+    return (0,_helpers_js__WEBPACK_IMPORTED_MODULE_2__.unescape)(this.tokens.name.value);
+  }
+  get inheritance() {
+    if (!this.tokens.inheritance) {
+      return null;
+    }
+    return (0,_helpers_js__WEBPACK_IMPORTED_MODULE_2__.unescape)(this.tokens.inheritance.value);
+  }
+
+  *validate(defs) {
+    for (const member of this.members) {
+      if (member.validate) {
+        yield* member.validate(defs);
+      }
+    }
+  }
+
+  /** @param {import("../writer.js").Writer} w */
+  write(w) {
+    const inheritance = () => {
+      if (!this.tokens.inheritance) {
+        return "";
+      }
+      return w.ts.wrap([
+        w.token(this.tokens.colon),
+        w.ts.trivia(this.tokens.inheritance.trivia),
+        w.ts.inheritance(
+          w.reference(this.tokens.inheritance.value, { context: this })
+        ),
+      ]);
+    };
+
+    return w.ts.definition(
+      w.ts.wrap([
+        this.extAttrs.write(w),
+        w.token(this.tokens.callback),
+        w.token(this.tokens.partial),
+        w.token(this.tokens.base),
+        w.token(this.tokens.mixin),
+        w.name_token(this.tokens.name, { data: this }),
+        inheritance(),
+        w.token(this.tokens.open),
+        w.ts.wrap(this.members.map((m) => m.write(w))),
+        w.token(this.tokens.close),
+        w.token(this.tokens.termination),
+      ]),
+      { data: this }
+    );
+  }
+}
+
+
+/***/ }),
+/* 21 */
+/***/ ((__unused_webpack___webpack_module__, __webpack_exports__, __webpack_require__) => {
+
+__webpack_require__.r(__webpack_exports__);
+/* harmony export */ __webpack_require__.d(__webpack_exports__, {
+/* harmony export */   "Constant": () => (/* binding */ Constant)
+/* harmony export */ });
+/* harmony import */ var _base_js__WEBPACK_IMPORTED_MODULE_0__ = __webpack_require__(6);
+/* harmony import */ var _type_js__WEBPACK_IMPORTED_MODULE_1__ = __webpack_require__(5);
+/* harmony import */ var _helpers_js__WEBPACK_IMPORTED_MODULE_2__ = __webpack_require__(4);
+
+
+
+
+class Constant extends _base_js__WEBPACK_IMPORTED_MODULE_0__.Base {
+  /**
+   * @param {import("../tokeniser.js").Tokeniser} tokeniser
+   */
+  static parse(tokeniser) {
+    /** @type {Base["tokens"]} */
+    const tokens = {};
+    tokens.base = tokeniser.consume("const");
+    if (!tokens.base) {
+      return;
+    }
+    let idlType = (0,_helpers_js__WEBPACK_IMPORTED_MODULE_2__.primitive_type)(tokeniser);
+    if (!idlType) {
+      const base =
+        tokeniser.consumeKind("identifier") ||
+        tokeniser.error("Const lacks a type");
+      idlType = new _type_js__WEBPACK_IMPORTED_MODULE_1__.Type({ source: tokeniser.source, tokens: { base } });
+    }
+    if (tokeniser.probe("?")) {
+      tokeniser.error("Unexpected nullable constant type");
+    }
+    idlType.type = "const-type";
+    tokens.name =
+      tokeniser.consumeKind("identifier") ||
+      tokeniser.error("Const lacks a name");
+    tokens.assign =
+      tokeniser.consume("=") || tokeniser.error("Const lacks value assignment");
+    tokens.value =
+      (0,_helpers_js__WEBPACK_IMPORTED_MODULE_2__.const_value)(tokeniser) || tokeniser.error("Const lacks a value");
+    tokens.termination =
+      tokeniser.consume(";") ||
+      tokeniser.error("Unterminated const, expected `;`");
+    const ret = new Constant({ source: tokeniser.source, tokens });
+    (0,_helpers_js__WEBPACK_IMPORTED_MODULE_2__.autoParenter)(ret).idlType = idlType;
+    return ret;
+  }
+
+  get type() {
+    return "const";
+  }
+  get name() {
+    return (0,_helpers_js__WEBPACK_IMPORTED_MODULE_2__.unescape)(this.tokens.name.value);
+  }
+  get value() {
+    return (0,_helpers_js__WEBPACK_IMPORTED_MODULE_2__.const_data)(this.tokens.value);
+  }
+
+  /** @param {import("../writer.js").Writer} w */
+  write(w) {
+    const { parent } = this;
+    return w.ts.definition(
+      w.ts.wrap([
+        this.extAttrs.write(w),
+        w.token(this.tokens.base),
+        w.ts.type(this.idlType.write(w)),
+        w.name_token(this.tokens.name, { data: this, parent }),
+        w.token(this.tokens.assign),
+        w.token(this.tokens.value),
+        w.token(this.tokens.termination),
+      ]),
+      { data: this, parent }
+    );
+  }
+}
+
+
+/***/ }),
+/* 22 */
+/***/ ((__unused_webpack___webpack_module__, __webpack_exports__, __webpack_require__) => {
+
+__webpack_require__.r(__webpack_exports__);
+/* harmony export */ __webpack_require__.d(__webpack_exports__, {
+/* harmony export */   "IterableLike": () => (/* binding */ IterableLike)
+/* harmony export */ });
+/* harmony import */ var _base_js__WEBPACK_IMPORTED_MODULE_0__ = __webpack_require__(6);
+/* harmony import */ var _helpers_js__WEBPACK_IMPORTED_MODULE_1__ = __webpack_require__(4);
+
+
+
+class IterableLike extends _base_js__WEBPACK_IMPORTED_MODULE_0__.Base {
+  /**
+   * @param {import("../tokeniser.js").Tokeniser} tokeniser
+   */
+  static parse(tokeniser) {
+    const start_position = tokeniser.position;
+    const ret = (0,_helpers_js__WEBPACK_IMPORTED_MODULE_1__.autoParenter)(
+      new IterableLike({ source: tokeniser.source, tokens: {} })
+    );
+    const { tokens } = ret;
+    tokens.readonly = tokeniser.consume("readonly");
+    if (!tokens.readonly) {
+      tokens.async = tokeniser.consume("async");
+    }
+    tokens.base = tokens.readonly
+      ? tokeniser.consume("maplike", "setlike")
+      : tokens.async
+      ? tokeniser.consume("iterable")
+      : tokeniser.consume("iterable", "maplike", "setlike");
+    if (!tokens.base) {
+      tokeniser.unconsume(start_position);
+      return;
+    }
+
+    const { type } = ret;
+    const secondTypeRequired = type === "maplike";
+    const secondTypeAllowed = secondTypeRequired || type === "iterable";
+    const argumentAllowed = ret.async && type === "iterable";
+
+    tokens.open =
+      tokeniser.consume("<") ||
+      tokeniser.error(`Missing less-than sign \`<\` in ${type} declaration`);
+    const first =
+      (0,_helpers_js__WEBPACK_IMPORTED_MODULE_1__.type_with_extended_attributes)(tokeniser) ||
+      tokeniser.error(`Missing a type argument in ${type} declaration`);
+    ret.idlType = [first];
+    ret.arguments = [];
+
+    if (secondTypeAllowed) {
+      first.tokens.separator = tokeniser.consume(",");
+      if (first.tokens.separator) {
+        ret.idlType.push((0,_helpers_js__WEBPACK_IMPORTED_MODULE_1__.type_with_extended_attributes)(tokeniser));
+      } else if (secondTypeRequired) {
+        tokeniser.error(`Missing second type argument in ${type} declaration`);
+      }
+    }
+
+    tokens.close =
+      tokeniser.consume(">") ||
+      tokeniser.error(`Missing greater-than sign \`>\` in ${type} declaration`);
+
+    if (tokeniser.probe("(")) {
+      if (argumentAllowed) {
+        tokens.argsOpen = tokeniser.consume("(");
+        ret.arguments.push(...(0,_helpers_js__WEBPACK_IMPORTED_MODULE_1__.argument_list)(tokeniser));
+        tokens.argsClose =
+          tokeniser.consume(")") ||
+          tokeniser.error("Unterminated async iterable argument list");
+      } else {
+        tokeniser.error(`Arguments are only allowed for \`async iterable\``);
+      }
+    }
+
+    tokens.termination =
+      tokeniser.consume(";") ||
+      tokeniser.error(`Missing semicolon after ${type} declaration`);
+
+    return ret.this;
+  }
+
+  get type() {
+    return this.tokens.base.value;
+  }
+  get readonly() {
+    return !!this.tokens.readonly;
+  }
+  get async() {
+    return !!this.tokens.async;
+  }
+
+  *validate(defs) {
+    for (const type of this.idlType) {
+      yield* type.validate(defs);
+    }
+    for (const argument of this.arguments) {
+      yield* argument.validate(defs);
+    }
+  }
+
+  /** @param {import("../writer.js").Writer} w */
+  write(w) {
+    return w.ts.definition(
+      w.ts.wrap([
+        this.extAttrs.write(w),
+        w.token(this.tokens.readonly),
+        w.token(this.tokens.async),
+        w.token(this.tokens.base, w.ts.generic),
+        w.token(this.tokens.open),
+        w.ts.wrap(this.idlType.map((t) => t.write(w))),
+        w.token(this.tokens.close),
+        w.token(this.tokens.argsOpen),
+        w.ts.wrap(this.arguments.map((arg) => arg.write(w))),
+        w.token(this.tokens.argsClose),
+        w.token(this.tokens.termination),
+      ]),
+      { data: this, parent: this.parent }
+    );
+  }
+}
+
+
+/***/ }),
+/* 23 */
+/***/ ((__unused_webpack___webpack_module__, __webpack_exports__, __webpack_require__) => {
+
+__webpack_require__.r(__webpack_exports__);
+/* harmony export */ __webpack_require__.d(__webpack_exports__, {
+/* harmony export */   "checkInterfaceMemberDuplication": () => (/* binding */ checkInterfaceMemberDuplication)
+/* harmony export */ });
+/* harmony import */ var _error_js__WEBPACK_IMPORTED_MODULE_0__ = __webpack_require__(3);
+
+
+/**
+ * @param {import("../validator.js").Definitions} defs
+ * @param {import("../productions/container.js").Container} i
+ */
+function* checkInterfaceMemberDuplication(defs, i) {
+  const opNames = groupOperationNames(i);
+  const partials = defs.partials.get(i.name) || [];
+  const mixins = defs.mixinMap.get(i.name) || [];
+  for (const ext of [...partials, ...mixins]) {
+    const additions = getOperations(ext);
+    const statics = additions.filter((a) => a.special === "static");
+    const nonstatics = additions.filter((a) => a.special !== "static");
+    yield* checkAdditions(statics, opNames.statics, ext, i);
+    yield* checkAdditions(nonstatics, opNames.nonstatics, ext, i);
+    statics.forEach((op) => opNames.statics.add(op.name));
+    nonstatics.forEach((op) => opNames.nonstatics.add(op.name));
+  }
+
+  /**
+   * @param {import("../productions/operation.js").Operation[]} additions
+   * @param {Set<string>} existings
+   * @param {import("../productions/container.js").Container} ext
+   * @param {import("../productions/container.js").Container} base
+   */
+  function* checkAdditions(additions, existings, ext, base) {
+    for (const addition of additions) {
+      const { name } = addition;
+      if (name && existings.has(name)) {
+        const isStatic = addition.special === "static" ? "static " : "";
+        const message = `The ${isStatic}operation "${name}" has already been defined for the base interface "${base.name}" either in itself or in a mixin`;
+        yield (0,_error_js__WEBPACK_IMPORTED_MODULE_0__.validationError)(
+          addition.tokens.name,
+          ext,
+          "no-cross-overload",
+          message
+        );
+      }
+    }
+  }
+
+  /**
+   * @param {import("../productions/container.js").Container} i
+   * @returns {import("../productions/operation.js").Operation[]}
+   */
+  function getOperations(i) {
+    return i.members.filter(({ type }) => type === "operation");
+  }
+
+  /**
+   * @param {import("../productions/container.js").Container} i
+   */
+  function groupOperationNames(i) {
+    const ops = getOperations(i);
+    return {
+      statics: new Set(
+        ops.filter((op) => op.special === "static").map((op) => op.name)
+      ),
+      nonstatics: new Set(
+        ops.filter((op) => op.special !== "static").map((op) => op.name)
+      ),
+    };
+  }
+}
+
+
+/***/ }),
+/* 24 */
+/***/ ((__unused_webpack___webpack_module__, __webpack_exports__, __webpack_require__) => {
+
+__webpack_require__.r(__webpack_exports__);
+/* harmony export */ __webpack_require__.d(__webpack_exports__, {
+/* harmony export */   "Constructor": () => (/* binding */ Constructor)
+/* harmony export */ });
+/* harmony import */ var _base_js__WEBPACK_IMPORTED_MODULE_0__ = __webpack_require__(6);
+/* harmony import */ var _helpers_js__WEBPACK_IMPORTED_MODULE_1__ = __webpack_require__(4);
+
+
+
+class Constructor extends _base_js__WEBPACK_IMPORTED_MODULE_0__.Base {
+  /**
+   * @param {import("../tokeniser.js").Tokeniser} tokeniser
+   */
+  static parse(tokeniser) {
+    const base = tokeniser.consume("constructor");
+    if (!base) {
+      return;
+    }
+    /** @type {Base["tokens"]} */
+    const tokens = { base };
+    tokens.open =
+      tokeniser.consume("(") ||
+      tokeniser.error("No argument list in constructor");
+    const args = (0,_helpers_js__WEBPACK_IMPORTED_MODULE_1__.argument_list)(tokeniser);
+    tokens.close =
+      tokeniser.consume(")") || tokeniser.error("Unterminated constructor");
+    tokens.termination =
+      tokeniser.consume(";") ||
+      tokeniser.error("No semicolon after constructor");
+    const ret = new Constructor({ source: tokeniser.source, tokens });
+    (0,_helpers_js__WEBPACK_IMPORTED_MODULE_1__.autoParenter)(ret).arguments = args;
+    return ret;
+  }
+
+  get type() {
+    return "constructor";
+  }
+
+  *validate(defs) {
+    for (const argument of this.arguments) {
+      yield* argument.validate(defs);
+    }
+  }
+
+  /** @param {import("../writer.js").Writer} w */
+  write(w) {
+    const { parent } = this;
+    return w.ts.definition(
+      w.ts.wrap([
+        this.extAttrs.write(w),
+        w.token(this.tokens.base, w.ts.nameless, { data: this, parent }),
+        w.token(this.tokens.open),
+        w.ts.wrap(this.arguments.map((arg) => arg.write(w))),
+        w.token(this.tokens.close),
+        w.token(this.tokens.termination),
+      ]),
+      { data: this, parent }
+    );
+  }
+}
+
+
+/***/ }),
+/* 25 */
+/***/ ((__unused_webpack___webpack_module__, __webpack_exports__, __webpack_require__) => {
+
+__webpack_require__.r(__webpack_exports__);
+/* harmony export */ __webpack_require__.d(__webpack_exports__, {
+/* harmony export */   "Mixin": () => (/* binding */ Mixin)
+/* harmony export */ });
+/* harmony import */ var _container_js__WEBPACK_IMPORTED_MODULE_0__ = __webpack_require__(20);
+/* harmony import */ var _constant_js__WEBPACK_IMPORTED_MODULE_1__ = __webpack_require__(21);
+/* harmony import */ var _attribute_js__WEBPACK_IMPORTED_MODULE_2__ = __webpack_require__(14);
+/* harmony import */ var _operation_js__WEBPACK_IMPORTED_MODULE_3__ = __webpack_require__(13);
+/* harmony import */ var _helpers_js__WEBPACK_IMPORTED_MODULE_4__ = __webpack_require__(4);
+
+
+
+
+
+
+class Mixin extends _container_js__WEBPACK_IMPORTED_MODULE_0__.Container {
+  /**
+   * @typedef {import("../tokeniser.js").Token} Token
+   *
+   * @param {import("../tokeniser.js").Tokeniser} tokeniser
+   * @param {Token} base
+   * @param {object} [options]
+   * @param {Token} [options.partial]
+   */
+  static parse(tokeniser, base, { partial } = {}) {
+    const tokens = { partial, base };
+    tokens.mixin = tokeniser.consume("mixin");
+    if (!tokens.mixin) {
+      return;
+    }
+    return _container_js__WEBPACK_IMPORTED_MODULE_0__.Container.parse(
+      tokeniser,
+      new Mixin({ source: tokeniser.source, tokens }),
+      {
+        allowedMembers: [
+          [_constant_js__WEBPACK_IMPORTED_MODULE_1__.Constant.parse],
+          [_helpers_js__WEBPACK_IMPORTED_MODULE_4__.stringifier],
+          [_attribute_js__WEBPACK_IMPORTED_MODULE_2__.Attribute.parse, { noInherit: true }],
+          [_operation_js__WEBPACK_IMPORTED_MODULE_3__.Operation.parse, { regular: true }],
+        ],
+      }
+    );
+  }
+
+  get type() {
+    return "interface mixin";
+  }
+}
+
+
+/***/ }),
+/* 26 */
+/***/ ((__unused_webpack___webpack_module__, __webpack_exports__, __webpack_require__) => {
+
+__webpack_require__.r(__webpack_exports__);
+/* harmony export */ __webpack_require__.d(__webpack_exports__, {
+/* harmony export */   "Dictionary": () => (/* binding */ Dictionary)
+/* harmony export */ });
+/* harmony import */ var _container_js__WEBPACK_IMPORTED_MODULE_0__ = __webpack_require__(20);
+/* harmony import */ var _field_js__WEBPACK_IMPORTED_MODULE_1__ = __webpack_require__(27);
+
+
+
+class Dictionary extends _container_js__WEBPACK_IMPORTED_MODULE_0__.Container {
+  /**
+   * @param {import("../tokeniser.js").Tokeniser} tokeniser
+   * @param {object} [options]
+   * @param {import("../tokeniser.js").Token} [options.partial]
+   */
+  static parse(tokeniser, { partial } = {}) {
+    const tokens = { partial };
+    tokens.base = tokeniser.consume("dictionary");
+    if (!tokens.base) {
+      return;
+    }
+    return _container_js__WEBPACK_IMPORTED_MODULE_0__.Container.parse(
+      tokeniser,
+      new Dictionary({ source: tokeniser.source, tokens }),
+      {
+        inheritable: !partial,
+        allowedMembers: [[_field_js__WEBPACK_IMPORTED_MODULE_1__.Field.parse]],
+      }
+    );
+  }
+
+  get type() {
+    return "dictionary";
+  }
+}
+
+
+/***/ }),
+/* 27 */
+/***/ ((__unused_webpack___webpack_module__, __webpack_exports__, __webpack_require__) => {
+
+__webpack_require__.r(__webpack_exports__);
+/* harmony export */ __webpack_require__.d(__webpack_exports__, {
+/* harmony export */   "Field": () => (/* binding */ Field)
+/* harmony export */ });
+/* harmony import */ var _base_js__WEBPACK_IMPORTED_MODULE_0__ = __webpack_require__(6);
+/* harmony import */ var _helpers_js__WEBPACK_IMPORTED_MODULE_1__ = __webpack_require__(4);
+/* harmony import */ var _extended_attributes_js__WEBPACK_IMPORTED_MODULE_2__ = __webpack_require__(8);
+/* harmony import */ var _default_js__WEBPACK_IMPORTED_MODULE_3__ = __webpack_require__(12);
+
+
+
+
+
+class Field extends _base_js__WEBPACK_IMPORTED_MODULE_0__.Base {
+  /**
+   * @param {import("../tokeniser.js").Tokeniser} tokeniser
+   */
+  static parse(tokeniser) {
+    /** @type {Base["tokens"]} */
+    const tokens = {};
+    const ret = (0,_helpers_js__WEBPACK_IMPORTED_MODULE_1__.autoParenter)(new Field({ source: tokeniser.source, tokens }));
+    ret.extAttrs = _extended_attributes_js__WEBPACK_IMPORTED_MODULE_2__.ExtendedAttributes.parse(tokeniser);
+    tokens.required = tokeniser.consume("required");
+    ret.idlType =
+      (0,_helpers_js__WEBPACK_IMPORTED_MODULE_1__.type_with_extended_attributes)(tokeniser, "dictionary-type") ||
+      tokeniser.error("Dictionary member lacks a type");
+    tokens.name =
+      tokeniser.consumeKind("identifier") ||
+      tokeniser.error("Dictionary member lacks a name");
+    ret.default = _default_js__WEBPACK_IMPORTED_MODULE_3__.Default.parse(tokeniser);
+    if (tokens.required && ret.default)
+      tokeniser.error("Required member must not have a default");
+    tokens.termination =
+      tokeniser.consume(";") ||
+      tokeniser.error("Unterminated dictionary member, expected `;`");
+    return ret.this;
+  }
+
+  get type() {
+    return "field";
+  }
+  get name() {
+    return (0,_helpers_js__WEBPACK_IMPORTED_MODULE_1__.unescape)(this.tokens.name.value);
+  }
+  get required() {
+    return !!this.tokens.required;
+  }
+
+  *validate(defs) {
+    yield* this.idlType.validate(defs);
+  }
+
+  /** @param {import("../writer.js").Writer} w */
+  write(w) {
+    const { parent } = this;
+    return w.ts.definition(
+      w.ts.wrap([
+        this.extAttrs.write(w),
+        w.token(this.tokens.required),
+        w.ts.type(this.idlType.write(w)),
+        w.name_token(this.tokens.name, { data: this, parent }),
+        this.default ? this.default.write(w) : "",
+        w.token(this.tokens.termination),
+      ]),
+      { data: this, parent }
+    );
+  }
+}
+
+
+/***/ }),
+/* 28 */
+/***/ ((__unused_webpack___webpack_module__, __webpack_exports__, __webpack_require__) => {
+
+__webpack_require__.r(__webpack_exports__);
+/* harmony export */ __webpack_require__.d(__webpack_exports__, {
+/* harmony export */   "Namespace": () => (/* binding */ Namespace)
+/* harmony export */ });
+/* harmony import */ var _container_js__WEBPACK_IMPORTED_MODULE_0__ = __webpack_require__(20);
+/* harmony import */ var _attribute_js__WEBPACK_IMPORTED_MODULE_1__ = __webpack_require__(14);
+/* harmony import */ var _operation_js__WEBPACK_IMPORTED_MODULE_2__ = __webpack_require__(13);
+/* harmony import */ var _error_js__WEBPACK_IMPORTED_MODULE_3__ = __webpack_require__(3);
+/* harmony import */ var _helpers_js__WEBPACK_IMPORTED_MODULE_4__ = __webpack_require__(4);
+/* harmony import */ var _constant_js__WEBPACK_IMPORTED_MODULE_5__ = __webpack_require__(21);
+
+
+
+
+
+
+
+class Namespace extends _container_js__WEBPACK_IMPORTED_MODULE_0__.Container {
+  /**
+   * @param {import("../tokeniser.js").Tokeniser} tokeniser
+   * @param {object} [options]
+   * @param {import("../tokeniser.js").Token} [options.partial]
+   */
+  static parse(tokeniser, { partial } = {}) {
+    const tokens = { partial };
+    tokens.base = tokeniser.consume("namespace");
+    if (!tokens.base) {
+      return;
+    }
+    return _container_js__WEBPACK_IMPORTED_MODULE_0__.Container.parse(
+      tokeniser,
+      new Namespace({ source: tokeniser.source, tokens }),
+      {
+        allowedMembers: [
+          [_attribute_js__WEBPACK_IMPORTED_MODULE_1__.Attribute.parse, { noInherit: true, readonly: true }],
+          [_constant_js__WEBPACK_IMPORTED_MODULE_5__.Constant.parse],
+          [_operation_js__WEBPACK_IMPORTED_MODULE_2__.Operation.parse, { regular: true }],
+        ],
+      }
+    );
+  }
+
+  get type() {
+    return "namespace";
+  }
+
+  *validate(defs) {
+    if (
+      !this.partial &&
+      this.extAttrs.every((extAttr) => extAttr.name !== "Exposed")
+    ) {
+      const message = `Namespaces must have [Exposed] extended attribute. \
+To fix, add, for example, [Exposed=Window]. Please also consider carefully \
+if your namespace should also be exposed in a Worker scope. Refer to the \
+[WebIDL spec section on Exposed](https://heycam.github.io/webidl/#Exposed) \
+for more information.`;
+      yield (0,_error_js__WEBPACK_IMPORTED_MODULE_3__.validationError)(
+        this.tokens.name,
+        this,
+        "require-exposed",
+        message,
+        {
+          autofix: (0,_helpers_js__WEBPACK_IMPORTED_MODULE_4__.autofixAddExposedWindow)(this),
+        }
+      );
+    }
+    yield* super.validate(defs);
+  }
+}
+
+
+/***/ }),
+/* 29 */
+/***/ ((__unused_webpack___webpack_module__, __webpack_exports__, __webpack_require__) => {
+
+__webpack_require__.r(__webpack_exports__);
+/* harmony export */ __webpack_require__.d(__webpack_exports__, {
+/* harmony export */   "CallbackInterface": () => (/* binding */ CallbackInterface)
+/* harmony export */ });
+/* harmony import */ var _container_js__WEBPACK_IMPORTED_MODULE_0__ = __webpack_require__(20);
+/* harmony import */ var _operation_js__WEBPACK_IMPORTED_MODULE_1__ = __webpack_require__(13);
+/* harmony import */ var _constant_js__WEBPACK_IMPORTED_MODULE_2__ = __webpack_require__(21);
+
+
+
+
+class CallbackInterface extends _container_js__WEBPACK_IMPORTED_MODULE_0__.Container {
+  /**
+   * @param {import("../tokeniser.js").Tokeniser} tokeniser
+   */
+  static parse(tokeniser, callback, { partial = null } = {}) {
+    const tokens = { callback };
+    tokens.base = tokeniser.consume("interface");
+    if (!tokens.base) {
+      return;
+    }
+    return _container_js__WEBPACK_IMPORTED_MODULE_0__.Container.parse(
+      tokeniser,
+      new CallbackInterface({ source: tokeniser.source, tokens }),
+      {
+        inheritable: !partial,
+        allowedMembers: [
+          [_constant_js__WEBPACK_IMPORTED_MODULE_2__.Constant.parse],
+          [_operation_js__WEBPACK_IMPORTED_MODULE_1__.Operation.parse, { regular: true }],
+        ],
+      }
+    );
+  }
+
+  get type() {
+    return "callback interface";
+  }
+}
+
+
+/***/ }),
+/* 30 */
+/***/ ((__unused_webpack___webpack_module__, __webpack_exports__, __webpack_require__) => {
+
+__webpack_require__.r(__webpack_exports__);
+/* harmony export */ __webpack_require__.d(__webpack_exports__, {
+/* harmony export */   "Writer": () => (/* binding */ Writer),
+/* harmony export */   "write": () => (/* binding */ write)
+/* harmony export */ });
+function noop(arg) {
+  return arg;
+}
+
+const templates = {
+  wrap: (items) => items.join(""),
+  trivia: noop,
+  name: noop,
+  reference: noop,
+  type: noop,
+  generic: noop,
+  nameless: noop,
+  inheritance: noop,
+  definition: noop,
+  extendedAttribute: noop,
+  extendedAttributeReference: noop,
+};
+
+class Writer {
+  constructor(ts) {
+    this.ts = Object.assign({}, templates, ts);
+  }
+
+  /**
+   * @param {string} raw
+   * @param {object} options
+   * @param {string} [options.unescaped]
+   * @param {import("./productions/base.js").Base} [options.context]
+   * @returns
+   */
+  reference(raw, { unescaped, context }) {
+    if (!unescaped) {
+      unescaped = raw.startsWith("_") ? raw.slice(1) : raw;
+    }
+    return this.ts.reference(raw, unescaped, context);
+  }
+
+  /**
+   * @param {import("./tokeniser.js").Token} t
+   * @param {Function} wrapper
+   * @param {...any} args
+   * @returns
+   */
+  token(t, wrapper = noop, ...args) {
+    if (!t) {
+      return "";
+    }
+    const value = wrapper(t.value, ...args);
+    return this.ts.wrap([this.ts.trivia(t.trivia), value]);
+  }
+
+  reference_token(t, context) {
+    return this.token(t, this.reference.bind(this), { context });
+  }
+
+  name_token(t, arg) {
+    return this.token(t, this.ts.name, arg);
+  }
+
+  identifier(id, context) {
+    return this.ts.wrap([
+      this.reference_token(id.tokens.value, context),
+      this.token(id.tokens.separator),
+    ]);
+  }
+}
+
+function write(ast, { templates: ts = templates } = {}) {
+  ts = Object.assign({}, templates, ts);
+
+  const w = new Writer(ts);
+
+  return ts.wrap(ast.map((it) => it.write(w)));
+}
+
+
+/***/ }),
+/* 31 */
+/***/ ((__unused_webpack___webpack_module__, __webpack_exports__, __webpack_require__) => {
+
+__webpack_require__.r(__webpack_exports__);
+/* harmony export */ __webpack_require__.d(__webpack_exports__, {
+/* harmony export */   "validate": () => (/* binding */ validate)
+/* harmony export */ });
+/* harmony import */ var _error_js__WEBPACK_IMPORTED_MODULE_0__ = __webpack_require__(3);
+
+
+function getMixinMap(all, unique) {
+  const map = new Map();
+  const includes = all.filter((def) => def.type === "includes");
+  for (const include of includes) {
+    const mixin = unique.get(include.includes);
+    if (!mixin) {
+      continue;
+    }
+    const array = map.get(include.target);
+    if (array) {
+      array.push(mixin);
+    } else {
+      map.set(include.target, [mixin]);
+    }
+  }
+  return map;
+}
+
+/**
+ * @typedef {ReturnType<typeof groupDefinitions>} Definitions
+ */
+function groupDefinitions(all) {
+  const unique = new Map();
+  const duplicates = new Set();
+  const partials = new Map();
+  for (const def of all) {
+    if (def.partial) {
+      const array = partials.get(def.name);
+      if (array) {
+        array.push(def);
+      } else {
+        partials.set(def.name, [def]);
+      }
+      continue;
+    }
+    if (!def.name) {
+      continue;
+    }
+    if (!unique.has(def.name)) {
+      unique.set(def.name, def);
+    } else {
+      duplicates.add(def);
+    }
+  }
+  return {
+    all,
+    unique,
+    partials,
+    duplicates,
+    mixinMap: getMixinMap(all, unique),
+    cache: {
+      typedefIncludesDictionary: new WeakMap(),
+      dictionaryIncludesRequiredField: new WeakMap(),
+    },
+  };
+}
+
+function* checkDuplicatedNames({ unique, duplicates }) {
+  for (const dup of duplicates) {
+    const { name } = dup;
+    const message = `The name "${name}" of type "${
+      unique.get(name).type
+    }" was already seen`;
+    yield (0,_error_js__WEBPACK_IMPORTED_MODULE_0__.validationError)(dup.tokens.name, dup, "no-duplicate", message);
+  }
+}
+
+function* validateIterable(ast) {
+  const defs = groupDefinitions(ast);
+  for (const def of defs.all) {
+    if (def.validate) {
+      yield* def.validate(defs);
+    }
+  }
+  yield* checkDuplicatedNames(defs);
+}
+
+// Remove this once all of our support targets expose `.flat()` by default
+function flatten(array) {
+  if (array.flat) {
+    return array.flat();
+  }
+  return [].concat(...array);
+}
+
+/**
+ * @param {import("./productions/base.js").Base[]} ast
+ * @return {import("./error.js").WebIDLErrorData[]} validation errors
+ */
+function validate(ast) {
+  return [...validateIterable(flatten(ast))];
+}
+
+
+/***/ })
+/******/ 	]);
+/************************************************************************/
+/******/ 	// The module cache
+/******/ 	var __webpack_module_cache__ = {};
+/******/ 	
+/******/ 	// The require function
+/******/ 	function __webpack_require__(moduleId) {
+/******/ 		// Check if module is in cache
+/******/ 		var cachedModule = __webpack_module_cache__[moduleId];
+/******/ 		if (cachedModule !== undefined) {
+/******/ 			return cachedModule.exports;
+/******/ 		}
+/******/ 		// Create a new module (and put it into the cache)
+/******/ 		var module = __webpack_module_cache__[moduleId] = {
+/******/ 			// no module.id needed
+/******/ 			// no module.loaded needed
+/******/ 			exports: {}
+/******/ 		};
+/******/ 	
+/******/ 		// Execute the module function
+/******/ 		__webpack_modules__[moduleId](module, module.exports, __webpack_require__);
+/******/ 	
+/******/ 		// Return the exports of the module
+/******/ 		return module.exports;
+/******/ 	}
+/******/ 	
+/************************************************************************/
+/******/ 	/* webpack/runtime/define property getters */
+/******/ 	(() => {
+/******/ 		// define getter functions for harmony exports
+/******/ 		__webpack_require__.d = (exports, definition) => {
+/******/ 			for(var key in definition) {
+/******/ 				if(__webpack_require__.o(definition, key) && !__webpack_require__.o(exports, key)) {
+/******/ 					Object.defineProperty(exports, key, { enumerable: true, get: definition[key] });
+/******/ 				}
+/******/ 			}
+/******/ 		};
+/******/ 	})();
+/******/ 	
+/******/ 	/* webpack/runtime/hasOwnProperty shorthand */
+/******/ 	(() => {
+/******/ 		__webpack_require__.o = (obj, prop) => (Object.prototype.hasOwnProperty.call(obj, prop))
+/******/ 	})();
+/******/ 	
+/******/ 	/* webpack/runtime/make namespace object */
+/******/ 	(() => {
+/******/ 		// define __esModule on exports
+/******/ 		__webpack_require__.r = (exports) => {
+/******/ 			if(typeof Symbol !== 'undefined' && Symbol.toStringTag) {
+/******/ 				Object.defineProperty(exports, Symbol.toStringTag, { value: 'Module' });
+/******/ 			}
+/******/ 			Object.defineProperty(exports, '__esModule', { value: true });
+/******/ 		};
+/******/ 	})();
+/******/ 	
+/************************************************************************/
+var __webpack_exports__ = {};
+// This entry need to be wrapped in an IIFE because it need to be isolated against other modules in the chunk.
+(() => {
+__webpack_require__.r(__webpack_exports__);
+/* harmony export */ __webpack_require__.d(__webpack_exports__, {
+/* harmony export */   "WebIDLParseError": () => (/* reexport safe */ _lib_tokeniser_js__WEBPACK_IMPORTED_MODULE_3__.WebIDLParseError),
+/* harmony export */   "parse": () => (/* reexport safe */ _lib_webidl2_js__WEBPACK_IMPORTED_MODULE_0__.parse),
+/* harmony export */   "validate": () => (/* reexport safe */ _lib_validator_js__WEBPACK_IMPORTED_MODULE_2__.validate),
+/* harmony export */   "write": () => (/* reexport safe */ _lib_writer_js__WEBPACK_IMPORTED_MODULE_1__.write)
+/* harmony export */ });
+/* harmony import */ var _lib_webidl2_js__WEBPACK_IMPORTED_MODULE_0__ = __webpack_require__(1);
+/* harmony import */ var _lib_writer_js__WEBPACK_IMPORTED_MODULE_1__ = __webpack_require__(30);
+/* harmony import */ var _lib_validator_js__WEBPACK_IMPORTED_MODULE_2__ = __webpack_require__(31);
+/* harmony import */ var _lib_tokeniser_js__WEBPACK_IMPORTED_MODULE_3__ = __webpack_require__(2);
+
+
+
+
+
+})();
+
+/******/ 	return __webpack_exports__;
+/******/ })()
+;
+});
+//# sourceMappingURL=webidl2.js.map
\ No newline at end of file
diff --git a/test/wpt/tests/resources/webidl2/lib/webidl2.js.headers b/test/wpt/tests/resources/webidl2/lib/webidl2.js.headers
new file mode 100644
index 0000000..6805c32
--- /dev/null
+++ b/test/wpt/tests/resources/webidl2/lib/webidl2.js.headers
@@ -0,0 +1 @@
+Content-Type: text/javascript; charset=utf-8