Adding upstream version 110.0.1.upstream/110.0.1upstream

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

153 files changed, 5238 insertions, 0 deletions

diff --git a/testing/web-platform/tests/webmessaging/Channel_postMessage_Blob.any.js b/testing/web-platform/tests/webmessaging/Channel_postMessage_Blob.any.js
new file mode 100644
index 0000000000..fce814f588
--- /dev/null
+++ b/testing/web-platform/tests/webmessaging/Channel_postMessage_Blob.any.js
@@ -0,0 +1,33 @@
+// META: title=postMessage() with a Blob
+// META: script=/common/gc.js
+
+    var TARGET = null;
+    var SOURCE = null;
+    var description = "Messages can contain Blobs.";
+
+    var t = async_test("Test Description: " + description);
+
+    var channel = new MessageChannel();
+    SOURCE = channel.port1;
+    TARGET = channel.port2;
+    TARGET.start();
+    TARGET.addEventListener("message", t.step_func(TestMessageEvent), true);
+
+    (function() {
+      SOURCE.postMessage({blob: new Blob(['foo', 'bar'])});
+    })();
+    garbageCollect();
+
+    function TestMessageEvent(evt)
+    {
+        assert_true('blob' in evt.data);
+        assert_true(evt.data.blob instanceof Blob);
+        assert_equals(evt.data.blob.size, 6);
+        const reader = new FileReader();
+        reader.onerror = t.unreached_func('Reading blob failed');
+        reader.onload = t.step_func(() => {
+            assert_equals(reader.result, 'foobar');
+            t.done();
+          });
+        reader.readAsText(evt.data.blob);
+    }
diff --git a/testing/web-platform/tests/webmessaging/Channel_postMessage_DataCloneErr.any.js b/testing/web-platform/tests/webmessaging/Channel_postMessage_DataCloneErr.any.js
new file mode 100644
index 0000000000..048820fa6b
--- /dev/null
+++ b/testing/web-platform/tests/webmessaging/Channel_postMessage_DataCloneErr.any.js
@@ -0,0 +1,14 @@
+// META: title=postMessage() with a host object raises DataCloneError
+
+    var description = "Throw a DataCloneError when a host object (e.g. a DOM node) is used with postMessage.";
+
+    test(function()
+    {
+        var channel = new MessageChannel();
+        channel.port1.start();
+
+        assert_throws_dom("DATA_CLONE_ERR", function()
+        {
+            channel.port1.postMessage(globalThis);
+        });
+    }, description);
diff --git a/testing/web-platform/tests/webmessaging/Channel_postMessage_clone_port.any.js b/testing/web-platform/tests/webmessaging/Channel_postMessage_clone_port.any.js
new file mode 100644
index 0000000000..3dcb902b77
--- /dev/null
+++ b/testing/web-platform/tests/webmessaging/Channel_postMessage_clone_port.any.js
@@ -0,0 +1,31 @@
+// META: title=postMessage(): clone a port
+
+    var OriginalPort = null;
+    var ClonedPort = null;
+    var description = "Test Description: When the user agent is to clone a port original port, with "
+                    + "the clone being owned by owner, it must return a new MessagePort object";
+
+    var t = async_test("Test Description: " + description);
+
+    var ChannelA = new MessageChannel();
+    var ChannelB = new MessageChannel();
+    OriginalPort = ChannelB.port2;
+
+    ChannelA.port2.onmessage = t.step_func(function(evt)
+    {
+        if(evt.data == "ports")
+        {
+            ClonedPort = evt.ports[0];
+
+            assert_not_equals(ClonedPort, OriginalPort, "new cloned port object should not equal to the original port!");
+
+            ClonedPort.onmessage = function(e)
+            {
+                test(function(){ assert_equals(e.data, "ping"); }, "Data sent through remote port is received by the new cloned port");
+                t.done();
+            }
+        }
+    });
+
+    ChannelA.port1.postMessage("ports", [OriginalPort]);
+    ChannelB.port1.postMessage("ping");
diff --git a/testing/web-platform/tests/webmessaging/Channel_postMessage_clone_port_error.any.js b/testing/web-platform/tests/webmessaging/Channel_postMessage_clone_port_error.any.js
new file mode 100644
index 0000000000..cbee47270c
--- /dev/null
+++ b/testing/web-platform/tests/webmessaging/Channel_postMessage_clone_port_error.any.js
@@ -0,0 +1,14 @@
+// META: title=postMessage() DataCloneError: cloning source port
+
+    var description = "Test Description: Throw a DataCloneError if transfer array in postMessage contains source port.";
+
+    test(function()
+    {
+        var channel = new MessageChannel();
+        channel.port1.start();
+
+        assert_throws_dom("DATA_CLONE_ERR", function()
+        {
+            channel.port1.postMessage("ports", [channel.port1]);
+        });
+    }, description);
diff --git a/testing/web-platform/tests/webmessaging/Channel_postMessage_event_properties.any.js b/testing/web-platform/tests/webmessaging/Channel_postMessage_event_properties.any.js
new file mode 100644
index 0000000000..0fd8c7e90a
--- /dev/null
+++ b/testing/web-platform/tests/webmessaging/Channel_postMessage_event_properties.any.js
@@ -0,0 +1,24 @@
+// META: title=postMessage(): MessageEvent properties
+
+    var TargetPort = null;
+    var description = "The postMessage() method - Create an event that uses the MessageEvent interface, "
+                    + "with the name message, which does not bubble and is not cancelable.";
+
+    var t = async_test("Test Description: " + description);
+
+    var channel = new MessageChannel();
+
+    TargetPort = channel.port2;
+    TargetPort.start();
+    TargetPort.addEventListener("message", t.step_func(TestMessageEvent), true);
+
+    channel.port1.postMessage("ping");
+
+    function TestMessageEvent(evt)
+    {
+        ExpectedResult = [true, "message", false, false];
+        ActualResult = [(evt instanceof MessageEvent), evt.type, evt.bubbles, evt.cancelable];
+
+        assert_array_equals(ActualResult, ExpectedResult);
+        t.done();
+    }
diff --git a/testing/web-platform/tests/webmessaging/Channel_postMessage_ports_readonly_array.any.js b/testing/web-platform/tests/webmessaging/Channel_postMessage_ports_readonly_array.any.js
new file mode 100644
index 0000000000..032a54e710
--- /dev/null
+++ b/testing/web-platform/tests/webmessaging/Channel_postMessage_ports_readonly_array.any.js
@@ -0,0 +1,28 @@
+// META: title=postMessage(): read-only ports array
+
+    "use strict";
+
+    var TargetPort = null;
+    var description = "The postMessage() method - Make new ports into a read only array.";
+
+    var t = async_test("Test Description: " + description);
+
+    var channel = new MessageChannel();
+
+    TargetPort = channel.port2;
+    TargetPort.start();
+    TargetPort.addEventListener("message", t.step_func(TestMessageEvent), true);
+
+    var channel2 = new MessageChannel();
+
+    channel.port1.postMessage("ports", [channel2.port1]);
+
+    function TestMessageEvent(evt)
+    {
+        var channel3 = new MessageChannel();
+        assert_throws_js(TypeError, () => {
+            evt.ports.push(channel3.port1);
+        }, "ports is a frozen object");
+        assert_equals(evt.ports.length, 1, "ports is a read only array with length == 1.");
+        t.done();
+    }
diff --git a/testing/web-platform/tests/webmessaging/Channel_postMessage_target_source.any.js b/testing/web-platform/tests/webmessaging/Channel_postMessage_target_source.any.js
new file mode 100644
index 0000000000..6b7fc7f20d
--- /dev/null
+++ b/testing/web-platform/tests/webmessaging/Channel_postMessage_target_source.any.js
@@ -0,0 +1,23 @@
+// META: title=postMessage(): target port and source port
+
+    var TARGET = null;
+    var SOURCE = null;
+    var description = "The postMessage() method - Let target port be the port with which source "
+                    + "port is entangled, if any.";
+
+    var t = async_test("Test Description: " + description);
+
+    var channel = new MessageChannel();
+    SOURCE = channel.port1;
+    TARGET = channel.port2;
+    TARGET.start();
+    TARGET.addEventListener("message", t.step_func(TestMessageEvent), true);
+
+    SOURCE.postMessage("ping");
+
+    function TestMessageEvent(evt)
+    {
+        assert_equals(evt.target, TARGET);
+        assert_not_equals(evt.target, SOURCE);
+        t.done();
+    }
diff --git a/testing/web-platform/tests/webmessaging/Channel_postMessage_transfer_xsite_incoming_messages.window.js b/testing/web-platform/tests/webmessaging/Channel_postMessage_transfer_xsite_incoming_messages.window.js
new file mode 100644
index 0000000000..23237ae155
--- /dev/null
+++ b/testing/web-platform/tests/webmessaging/Channel_postMessage_transfer_xsite_incoming_messages.window.js
@@ -0,0 +1,32 @@
+// META: script=/common/get-host-info.sub.js
+
+async_test(function(t) {
+  var channel1 = new MessageChannel();
+  var host = get_host_info();
+  let iframe = document.createElement('iframe');
+  iframe.src = host.HTTP_NOTSAMESITE_ORIGIN + "/webmessaging/support/ChildWindowPostMessage.htm";
+  document.body.appendChild(iframe);
+  var TARGET = document.querySelector("iframe").contentWindow;
+  iframe.onload = t.step_func(function() {
+    // Enable the port.
+    channel1.port1.onmessage = t.step_func(function (evt) {
+      assert_equals(Number(evt.data), 0);
+
+      // Send a message, expecting it to be received in the iframe.
+      channel1.port2.postMessage(1)
+
+      // Transfer the port.
+      TARGET.postMessage("ports", "*", [channel1.port1]);
+    });
+
+    // Send a message, expecting it to be received here.
+    channel1.port2.postMessage(0)
+
+    channel1.port2.onmessage = t.step_func(function (evt) {
+        assert_equals(Number(evt.data), 1);
+        t.done();
+      });
+  });
+}, `Tasks enqueued on the port-message-queue of an enabled port,
+  are transferred along with the port, when the transfer happens in the same task
+  during which postMessage is called`);
diff --git a/testing/web-platform/tests/webmessaging/Channel_postMessage_with_transfer_entangled.any.js b/testing/web-platform/tests/webmessaging/Channel_postMessage_with_transfer_entangled.any.js
new file mode 100644
index 0000000000..2226b27844
--- /dev/null
+++ b/testing/web-platform/tests/webmessaging/Channel_postMessage_with_transfer_entangled.any.js
@@ -0,0 +1,36 @@
+async_test(function(t) {
+    var channel1 = new MessageChannel();
+    var channel2 = new MessageChannel();
+
+     // One, send a message.
+     channel1.port1.postMessage(1);
+
+     // Two, transfer both ports.
+     channel2.port1.postMessage("transfer", [channel1.port1]);
+     channel2.port1.postMessage("transfer", [channel1.port2]);
+
+     var transfer_counter = 0;
+     var sender;
+     channel2.port2.onmessage = t.step_func(function (evt) {
+         if (transfer_counter == 0) {
+             sender = evt.ports[0];
+             transfer_counter = 1;
+         } else {
+             sender.postMessage(2);
+             var counter = 0;
+             evt.ports[0].onmessage = t.step_func(function (evt) {
+                 if (counter == 0) {
+                     assert_equals(evt.data, 1);
+                     counter = 1;
+                 } else if (counter == 1) {
+                     assert_equals(evt.data, 2);
+                     counter = 2;
+                 } else {
+                     assert_equals(evt.data, 3);
+                     t.done();
+                 }
+             });
+             sender.postMessage(3);
+         }
+      });
+}, "An entangled port transferred to the same origin receives messages in order");
diff --git a/testing/web-platform/tests/webmessaging/Channel_postMessage_with_transfer_incoming_messages.any.js b/testing/web-platform/tests/webmessaging/Channel_postMessage_with_transfer_incoming_messages.any.js
new file mode 100644
index 0000000000..fe2e96220d
--- /dev/null
+++ b/testing/web-platform/tests/webmessaging/Channel_postMessage_with_transfer_incoming_messages.any.js
@@ -0,0 +1,32 @@
+async_test(function(t) {
+  var channel1 = new MessageChannel();
+  var channel2 = new MessageChannel();
+  var channel3 = new MessageChannel();
+  channel2.port2.onmessage = t.step_func(function (evt) {
+    channel3.port1.onmessage = t.step_func(function (evt) {
+      var counter = 0;
+      evt.ports[0].onmessage = t.step_func(function (evt) {
+        if (counter == 0) {
+          assert_equals(evt.data, "First");
+          counter = 1;
+        } else if (counter == 1) {
+          assert_equals(evt.data, "Second");
+          counter = 2;
+        } else if (counter == 2) {
+          assert_equals(evt.data, "Third");
+          counter = 3;
+        } else if (counter == 3) {
+          assert_equals(evt.data, "Fourth");
+          t.done();
+        }
+      });
+      channel1.port2.postMessage("Fourth");
+    });
+    channel1.port2.postMessage("Second");
+    channel1.port2.postMessage("Third");
+    channel3.port2.postMessage("2", evt.ports);
+  });
+  channel1.port2.postMessage("First");
+  channel2.port1.postMessage("1", [channel1.port1]);
+}, `When transferring a non-enabled port mutiple times,
+    incoming messages sent at various transfer steps are received in order upon enablement.`);
diff --git a/testing/web-platform/tests/webmessaging/Channel_postMessage_with_transfer_outgoing_messages.any.js b/testing/web-platform/tests/webmessaging/Channel_postMessage_with_transfer_outgoing_messages.any.js
new file mode 100644
index 0000000000..aa80b7589c
--- /dev/null
+++ b/testing/web-platform/tests/webmessaging/Channel_postMessage_with_transfer_outgoing_messages.any.js
@@ -0,0 +1,35 @@
+
+async_test(function(t) {
+  var channel1 = new MessageChannel();
+  var channel2 = new MessageChannel();
+  var channel3 = new MessageChannel();
+  channel2.port2.onmessage = t.step_func(function (evt) {
+    evt.ports[0].postMessage("Second");
+    evt.ports[0].postMessage("Third");
+    channel3.port1.onmessage = t.step_func(function (evt) {
+      evt.ports[0].postMessage("Fourth");
+    });
+    channel3.port2.postMessage("2", evt.ports);
+  });
+  channel1.port1.postMessage("First");
+  channel2.port1.postMessage("1", [channel1.port1]);
+  var counter = 0;
+  channel1.port2.onmessage = t.step_func(function (evt) {
+    if (counter == 0) {
+      assert_equals(evt.data, "First");
+      counter = 1;
+    } else if (counter == 1) {
+      assert_equals(evt.data, "Second");
+      counter = 2;
+    }
+    else if (counter == 2) {
+      assert_equals(evt.data, "Third");
+      counter = 3;
+    }
+    else if (counter == 3) {
+      assert_equals(evt.data, "Fourth");
+      t.done();
+    }
+  });
+}, `When transferring a port,
+    outgoing messages sent at each transfer step are received in order by the entangled port.`);
diff --git a/testing/web-platform/tests/webmessaging/META.yml b/testing/web-platform/tests/webmessaging/META.yml
new file mode 100644
index 0000000000..95d5071171
--- /dev/null
+++ b/testing/web-platform/tests/webmessaging/META.yml
@@ -0,0 +1,6 @@
+spec: https://html.spec.whatwg.org/multipage/web-messaging.html
+suggested_reviewers:
+  - zqzhang
+  - jdm
+  - mkruisselbrink
+  - annevk
diff --git a/testing/web-platform/tests/webmessaging/MessageEvent-trusted.any.js b/testing/web-platform/tests/webmessaging/MessageEvent-trusted.any.js
new file mode 100644
index 0000000000..84187eb571
--- /dev/null
+++ b/testing/web-platform/tests/webmessaging/MessageEvent-trusted.any.js
@@ -0,0 +1,32 @@
+// META: title=MessagePort message events are trusted
+
+// See also:
+// - https://github.com/whatwg/html/issues/1602
+// - https://github.com/whatwg/html/pull/1935
+
+"use strict";
+
+async_test(t => {
+  assert_true("MessageChannel" in self, "The browser must support MessageChannel");
+
+  const channel = new MessageChannel();
+
+  channel.port2.onmessage = t.step_func_done(e => {
+    assert_equals(e.isTrusted, true);
+  });
+
+  channel.port1.postMessage("ping");
+}, "With a MessageChannel and its MessagePorts");
+
+async_test(t => {
+  assert_true("BroadcastChannel" in self, "The browser must support BroadcastChannel");
+
+  const channel = new BroadcastChannel("channel name");
+
+  channel.onmessage = t.step_func_done(e => {
+    assert_equals(e.isTrusted, true);
+  });
+
+  new Worker("support/MessageEvent-trusted-worker.js");
+}, "With a BroadcastChannel");
+
diff --git a/testing/web-platform/tests/webmessaging/MessageEvent-trusted.window.js b/testing/web-platform/tests/webmessaging/MessageEvent-trusted.window.js
new file mode 100644
index 0000000000..11cf48beed
--- /dev/null
+++ b/testing/web-platform/tests/webmessaging/MessageEvent-trusted.window.js
@@ -0,0 +1,9 @@
+// META: title=MessagePort message events are trusted with window
+
+async_test(t => {
+  window.onmessage = t.step_func_done(e => {
+    assert_equals(e.isTrusted, true);
+  });
+
+  window.postMessage("ping", "*");
+}, "With window");
diff --git a/testing/web-platform/tests/webmessaging/MessageEvent.any.js b/testing/web-platform/tests/webmessaging/MessageEvent.any.js
new file mode 100644
index 0000000000..0fb2636911
--- /dev/null
+++ b/testing/web-platform/tests/webmessaging/MessageEvent.any.js
@@ -0,0 +1,22 @@
+// META: title=MessageEvent
+
+var prefixes = ['moz', 'ms', 'o', 'webkit'];
+prefixes.forEach(function(prefix) {
+  var name = prefix + "InitMessageEvent";
+
+  test(function() {
+    assert_false(name in MessageEvent.prototype);
+  }, name + " on the prototype");
+
+  test(function() {
+    var event = new MessageEvent("message");
+    assert_false(name in event);
+  }, name + " on the instance");
+});
+
+test(function() {
+  var event = new MessageEvent("message");
+  assert_throws_js(TypeError, function() {
+    event.initMessageEvent();
+  }, "Not enough arguments to initMessageEvent");
+}, "initMessageEvent with no arguments");
diff --git a/testing/web-platform/tests/webmessaging/MessageEvent_onmessage_postMessage_infinite_loop.html b/testing/web-platform/tests/webmessaging/MessageEvent_onmessage_postMessage_infinite_loop.html
new file mode 100644
index 0000000000..179bc0cc4a
--- /dev/null
+++ b/testing/web-platform/tests/webmessaging/MessageEvent_onmessage_postMessage_infinite_loop.html
@@ -0,0 +1,31 @@
+<!DOCTYPE html>
+<html>
+<head>
+<title>MessageEvent: onmessage infinite loop</title>
+<script src="/resources/testharness.js"></script>
+<script src="/resources/testharnessreport.js"></script>
+</head>
+<body>
+<script>
+'use strict';
+
+// The test passes if the onmessage / postMessage loop does not prevent the
+// step_timeout task from ever being run. In particular there should be no
+// infinite loop or stack overflow.
+async_test(function(t) {
+  var channel = new MessageChannel();
+  var count = 0;
+  channel.port1.addEventListener("message", t.step_func(function() {
+    count++;
+    assert_less_than(count, 1000, "There were many message events without " +
+                                  "t.step_timeout ever being called.");
+  }));
+  channel.port1.addEventListener("message", t.step_func(function() {
+    channel.port2.postMessage(0);
+  }));
+  channel.port1.start();
+  channel.port2.postMessage(0);
+
+  t.step_timeout(function() { t.done(); }, 0);
+}, "onmessage calling source postMessage");
+</script>
diff --git a/testing/web-platform/tests/webmessaging/MessageEvent_properties.htm b/testing/web-platform/tests/webmessaging/MessageEvent_properties.htm
new file mode 100644
index 0000000000..389add98d1
--- /dev/null
+++ b/testing/web-platform/tests/webmessaging/MessageEvent_properties.htm
@@ -0,0 +1,32 @@
+<!DOCTYPE html>
+<html>
+<head>
+<title> MessageEvent interface and properties </title>
+<script src="/resources/testharness.js"></script>
+<script src="/resources/testharnessreport.js"></script>
+</head>
+<body>
+<div id=log></div>
+
+<div style="display:none">
+    <iframe width="70%" onload="do_test()" src="./support/ChildWindowPostMessage.htm"></iframe>
+</div>
+
+<script>
+async_test(function() {
+    window.do_test = this.step_func(function() {
+        document.querySelector("iframe").contentWindow.postMessage("foo", "*");
+    })
+
+    window.addEventListener("message", this.step_func_done(function(e) {
+        e.preventDefault();
+        assert_true(e instanceof MessageEvent, "Should be MessageEvent");
+        assert_equals(e.type, "message");
+        assert_false(e.bubbles, "bubbles");
+        assert_false(e.cancelable, "cancelable");
+        assert_false(e.defaultPrevented, "defaultPrevented");
+    }), false);
+});
+</script>
+</body>
+</html>
diff --git a/testing/web-platform/tests/webmessaging/MessagePort_initial_disabled.any.js b/testing/web-platform/tests/webmessaging/MessagePort_initial_disabled.any.js
new file mode 100644
index 0000000000..b897858175
--- /dev/null
+++ b/testing/web-platform/tests/webmessaging/MessagePort_initial_disabled.any.js
@@ -0,0 +1,10 @@
+// META: title=MessageChannel: port message queue is initially disabled
+
+// TODO: duplicate of ./message-channels/no-start.any.js?
+
+async_test(function(t) {
+  var channel = new MessageChannel();
+  channel.port2.addEventListener("message", t.unreached_func(), true);
+  channel.port1.postMessage("ping");
+  setTimeout(t.step_func_done(), 100);
+});
diff --git a/testing/web-platform/tests/webmessaging/MessagePort_onmessage_start.any.js b/testing/web-platform/tests/webmessaging/MessagePort_onmessage_start.any.js
new file mode 100644
index 0000000000..7ba3a37210
--- /dev/null
+++ b/testing/web-platform/tests/webmessaging/MessagePort_onmessage_start.any.js
@@ -0,0 +1,10 @@
+// META: title=MessageChannel: port.onmessage enables message queue
+
+// TODO: duplicate of ./message-channels/implied-start.any.js?
+
+async_test(function(t) {
+  var channel = new MessageChannel();
+  channel.port2.onmessage = t.step_func_done();
+  channel.port1.postMessage("ping");
+  t.step_timeout(t.unreached_func(), 1000);
+});
diff --git a/testing/web-platform/tests/webmessaging/README.md b/testing/web-platform/tests/webmessaging/README.md
new file mode 100644
index 0000000000..0b81aa0658
--- /dev/null
+++ b/testing/web-platform/tests/webmessaging/README.md
@@ -0,0 +1,2 @@
+These are the cross-document messaging (`postMessage()`) tests for the
+[cross-document messaging chapter of the HTML Standard](https://html.spec.whatwg.org/multipage/comms.html#web-messaging).
diff --git a/testing/web-platform/tests/webmessaging/Transferred_objects_unusable.sub.htm b/testing/web-platform/tests/webmessaging/Transferred_objects_unusable.sub.htm
new file mode 100644
index 0000000000..55c3dbdba1
--- /dev/null
+++ b/testing/web-platform/tests/webmessaging/Transferred_objects_unusable.sub.htm
@@ -0,0 +1,60 @@
+<!DOCTYPE html>
+<html>
+<head>
+<title> Transferred objects are no longer usable on the sending side </title>
+<script src="/resources/testharness.js"></script>
+<script src="/resources/testharnessreport.js"></script>
+</head>
+<body>
+<div id=log></div>
+
+<div style="display:none">
+    <iframe width="70%" onload="PostMessageTest()" src="{{location[scheme]}}://{{domains[www1]}}:{{location[port]}}/webmessaging/support/ChildWindowPostMessage.htm"></iframe>
+</div>
+
+<script>
+
+
+    var description = "Test Description: " +
+                      "Objects listed in transfer are transferred, not just cloned, meaning that they are " +
+                      "no longer usable on the sending side.";
+
+    var t = async_test(description);
+
+    var DATA = {test: "e.ports[0].postMessage('TRANSFERRED')"};
+    var TARGET = document.querySelector("iframe");
+    var ExpectedResult = ["PING", "TRANSFERRED"];
+    var ActualResult = [];
+
+    function PostMessageTest()
+    {
+        test(function()
+        {
+            assert_own_property(window, "MessageChannel", "window");
+
+            var channel = new MessageChannel();
+
+            channel.port2.onmessage = t.step_func(VerifyResult);
+
+            channel.port1.postMessage("PING");
+
+            TARGET.contentWindow.postMessage(DATA, "*", [channel.port1]);
+
+            channel.port1.postMessage("PONG");
+
+        }, "MessageChannel is supported.");
+    }
+
+    function VerifyResult(e)
+    {
+        ActualResult.push(e.data)
+
+        if (ActualResult.length >= ExpectedResult.length)
+        {
+            assert_array_equals(ActualResult, ExpectedResult, "ActualResult");
+            t.done();
+        }
+    }
+</script>
+</body>
+</html>
diff --git a/testing/web-platform/tests/webmessaging/broadcastchannel/basics.any.js b/testing/web-platform/tests/webmessaging/broadcastchannel/basics.any.js
new file mode 100644
index 0000000000..68b4706028
--- /dev/null
+++ b/testing/web-platform/tests/webmessaging/broadcastchannel/basics.any.js
@@ -0,0 +1,120 @@
+async_test(t => {
+    let c1 = new BroadcastChannel('eventType');
+    let c2 = new BroadcastChannel('eventType');
+
+    c2.onmessage = t.step_func(e => {
+        assert_true(e instanceof MessageEvent);
+        assert_equals(e.target, c2);
+        assert_equals(e.type, 'message');
+        assert_equals(e.origin, location.origin, 'origin');
+        assert_equals(e.data, 'hello world');
+        assert_equals(e.source, null, 'source');
+        t.done();
+      });
+    c1.postMessage('hello world');
+  }, 'postMessage results in correct event');
+
+async_test(t => {
+    let c1 = new BroadcastChannel('order');
+    let c2 = new BroadcastChannel('order');
+    let c3 = new BroadcastChannel('order');
+
+    let events = [];
+    let doneCount = 0;
+    let handler = t.step_func(e => {
+      events.push(e);
+      if (e.data == 'done') {
+        doneCount++;
+        if (doneCount == 2) {
+          assert_equals(events.length, 6);
+          assert_equals(events[0].target, c2, 'target for event 0');
+          assert_equals(events[0].data, 'from c1');
+          assert_equals(events[1].target, c3, 'target for event 1');
+          assert_equals(events[1].data, 'from c1');
+          assert_equals(events[2].target, c1, 'target for event 2');
+          assert_equals(events[2].data, 'from c3');
+          assert_equals(events[3].target, c2, 'target for event 3');
+          assert_equals(events[3].data, 'from c3');
+          assert_equals(events[4].target, c1, 'target for event 4');
+          assert_equals(events[4].data, 'done');
+          assert_equals(events[5].target, c3, 'target for event 5');
+          assert_equals(events[5].data, 'done');
+          t.done();
+        }
+      }
+    });
+    c1.onmessage = handler;
+    c2.onmessage = handler;
+    c3.onmessage = handler;
+
+    c1.postMessage('from c1');
+    c3.postMessage('from c3');
+    c2.postMessage('done');
+  }, 'messages are delivered in port creation order');
+
+async_test(t => {
+    let c1 = new BroadcastChannel('closed');
+    let c2 = new BroadcastChannel('closed');
+    let c3 = new BroadcastChannel('closed');
+
+    c2.onmessage = t.unreached_func();
+    c2.close();
+    c3.onmessage = t.step_func(() => t.done());
+    c1.postMessage('test');
+  }, 'messages aren\'t delivered to a closed port');
+
+ async_test(t => {
+    let c1 = new BroadcastChannel('closed');
+    let c2 = new BroadcastChannel('closed');
+    let c3 = new BroadcastChannel('closed');
+
+    c2.onmessage = t.unreached_func();
+    c3.onmessage = t.step_func(() => t.done());
+    c1.postMessage('test');
+    c2.close();
+}, 'messages aren\'t delivered to a port closed after calling postMessage.');
+
+async_test(t => {
+    let c1 = new BroadcastChannel('create-in-onmessage');
+    let c2 = new BroadcastChannel('create-in-onmessage');
+
+    c2.onmessage = t.step_func(e => {
+        assert_equals(e.data, 'first');
+        c2.close();
+        let c3 = new BroadcastChannel('create-in-onmessage');
+        c3.onmessage = t.step_func(event => {
+            assert_equals(event.data, 'done');
+            t.done();
+          });
+        c1.postMessage('done');
+      });
+    c1.postMessage('first');
+    c2.postMessage('second');
+  }, 'closing and creating channels during message delivery works correctly');
+
+async_test(t => {
+    let c1 = new BroadcastChannel('close-in-onmessage');
+    let c2 = new BroadcastChannel('close-in-onmessage');
+    let c3 = new BroadcastChannel('close-in-onmessage');
+    let events = [];
+    c1.onmessage = e => events.push('c1: ' + e.data);
+    c2.onmessage = e => events.push('c2: ' + e.data);
+    c3.onmessage = e => events.push('c3: ' + e.data);
+
+    // c2 closes itself when it receives the first message
+    c2.addEventListener('message', e => {
+        c2.close();
+      });
+
+    c3.addEventListener('message', t.step_func(e => {
+        if (e.data == 'done') {
+          assert_array_equals(events, [
+              'c2: first',
+              'c3: first',
+              'c3: done']);
+          t.done();
+        }
+      }));
+    c1.postMessage('first');
+    c1.postMessage('done');
+  }, 'Closing a channel in onmessage prevents already queued tasks from firing onmessage events');
diff --git a/testing/web-platform/tests/webmessaging/broadcastchannel/blobs.html b/testing/web-platform/tests/webmessaging/broadcastchannel/blobs.html
new file mode 100644
index 0000000000..ab5096b63c
--- /dev/null
+++ b/testing/web-platform/tests/webmessaging/broadcastchannel/blobs.html
@@ -0,0 +1,82 @@
+<!DOCTYPE html>
+<meta charset=utf-8>
+<script src="/resources/testharness.js"></script>
+<script src="/resources/testharnessreport.js"></script>
+<script src="/common/gc.js"></script>
+<script>
+async_test(t => {
+    const c1 = new BroadcastChannel('blob');
+    const c2 = new BroadcastChannel('blob');
+    const c3 = new BroadcastChannel('blob');
+
+    let readCount = 0;
+    c2.onmessage = t.step_func(e => {
+        // check blob
+        assert_true('blob' in e.data);
+        assert_true(e.data.blob instanceof Blob);
+        assert_equals(e.data.blob.size, 6);
+        const reader = new FileReader();
+        reader.onerror = t.unreached_func();
+        reader.onload = t.step_func(() => {
+            assert_equals(reader.result, 'foobar');
+            if (++readCount == 2)
+              t.done();
+          });
+        reader.readAsText(e.data.blob);
+      });
+    c3.onmessage = c2.onmessage;
+    (() => {
+      c1.postMessage({blob: new Blob(['foo', 'bar'])});
+    })();
+    garbageCollect();
+  }, 'Blobs work on BroadcastChannel');
+
+async_test(t => {
+    const c1 = new BroadcastChannel('blobworker');
+    const c2 = new BroadcastChannel('blobworker');
+    const events = [];
+
+    const verifyEvents = function() {
+        assert_equals(events.length, 5);
+        assert_equals(events[0], 'from worker');
+        assert_equals(events[1], 'from worker');
+        assert_true(events[2].blob instanceof Blob);
+        assert_equals(events[2].blob.size, 11);
+        assert_true(events[3].blob instanceof Blob);
+        assert_equals(events[3].blob.size, 11);
+        assert_equals(events[4], 'done');
+        const reader = new FileReader();
+        reader.onerror = t.unreached_func();
+        reader.onload = t.step_func(() => {
+            assert_equals(reader.result, 'hello-world');
+            t.done();
+          });
+        reader.readAsText(events[3].blob);
+    };
+
+    let receivedDone = false;
+    let receivedWorkerDone = false;
+
+    c1.onmessage = e => events.push(e.data);
+    c2.onmessage = e => events.push(e.data);
+    c2.addEventListener('message', t.step_func(e => {
+        if (e.data.blob)
+          c1.postMessage('done');
+        if (e.data === 'done')
+          receivedDone = true;
+        if (receivedDone && receivedWorkerDone)
+          verifyEvents();
+      }));
+
+    const worker = new Worker('resources/worker.js');
+    worker.onmessage = t.step_func(e => {
+        receivedWorkerDone = true;
+        if (receivedDone && receivedWorkerDone)
+          verifyEvents();
+      });
+    worker.postMessage({channel: 'blobworker'});
+    worker.postMessage({blob: ['hello-world']});
+
+  }, 'Blobs work with workers on BroadcastChannel');
+
+</script>
diff --git a/testing/web-platform/tests/webmessaging/broadcastchannel/cross-origin.html b/testing/web-platform/tests/webmessaging/broadcastchannel/cross-origin.html
new file mode 100644
index 0000000000..ee4b2f21c8
--- /dev/null
+++ b/testing/web-platform/tests/webmessaging/broadcastchannel/cross-origin.html
@@ -0,0 +1,38 @@
+<!DOCTYPE html>
+<meta charset=utf-8>
+<script src="/resources/testharness.js"></script>
+<script src="/resources/testharnessreport.js"></script>
+<script src="/common/get-host-info.sub.js"></script>
+<!-- Pull in the with_iframe helper function from the service worker tests -->
+<script src="/service-workers/service-worker/resources/test-helpers.sub.js"></script>
+<body>
+<script>
+
+const events = [];
+
+function testCompletion(t) {
+  return new Promise((resolve) => {
+    window.addEventListener("message", t.step_func(e => {
+      if (e.data == 'done') {
+        assert_equals(events.length, 0);
+        resolve();
+      }
+    }));
+  });
+}
+
+promise_test(async t => {
+
+  const bc0 = new BroadcastChannel('no-cross-origin-messages');
+  bc0.onmessage = e => {window.events.push(e);};
+
+  const testResults = testCompletion(t);
+  const url = get_host_info().HTTPS_NOTSAMESITE_ORIGIN +
+    '/webmessaging/broadcastchannel/resources/cross-origin.html';
+  await with_iframe(url);
+
+  return testResults;
+}, "Messages aren't delivered across origins");
+
+</script>
+</body>
diff --git a/testing/web-platform/tests/webmessaging/broadcastchannel/cross-partition.https.tentative.html b/testing/web-platform/tests/webmessaging/broadcastchannel/cross-partition.https.tentative.html
new file mode 100644
index 0000000000..4e91da5546
--- /dev/null
+++ b/testing/web-platform/tests/webmessaging/broadcastchannel/cross-partition.https.tentative.html
@@ -0,0 +1,356 @@
+<!DOCTYPE html>
+<meta charset=utf-8>
+<meta name="timeout" content="long">
+<script src="/resources/testharness.js"></script>
+<script src="/resources/testharnessreport.js"></script>
+<script src="/common/get-host-info.sub.js"></script>
+<script src="/common/utils.js"></script>
+<script src="/common/dispatcher/dispatcher.js"></script>
+<!-- Pull in executor_path needed by newPopup / newIframe -->
+<script src="/html/cross-origin-embedder-policy/credentialless/resources/common.js"></script>
+<!-- Pull in importScript / newPopup / newIframe -->
+<script src="/html/anonymous-iframe/resources/common.js"></script>
+<body>
+<script>
+
+const bc_postmessage_js = (channel_name, message, done_queue_name) => `
+  const bc = new BroadcastChannel("${channel_name}");
+  bc.postMessage("${message}");
+  send("${done_queue_name}", "done");
+`;
+
+const add_iframe_js = (iframe_origin, response_queue_uuid) => `
+  const importScript = ${importScript};
+  await importScript("/html/cross-origin-embedder-policy/credentialless" +
+                   "/resources/common.js");
+  await importScript("/html/anonymous-iframe/resources/common.js");
+  await importScript("/common/utils.js");
+  send("${response_queue_uuid}", newIframe("${iframe_origin}"));
+`;
+
+const same_site_origin = get_host_info().HTTPS_ORIGIN;
+const cross_site_origin = get_host_info().HTTPS_NOTSAMESITE_ORIGIN;
+
+async function create_test_iframes(t, response_queue_uuid) {
+
+  // Create a same-origin iframe in a cross-site popup.
+  const not_same_site_popup_uuid = newPopup(t, cross_site_origin);
+  send(not_same_site_popup_uuid,
+       add_iframe_js(same_site_origin, response_queue_uuid));
+  const iframe_1_uuid = await receive(response_queue_uuid);
+
+  // Create a same-origin iframe in a same-site popup.
+  const same_origin_popup_uuid = newPopup(t, same_site_origin);
+  send(same_origin_popup_uuid,
+       add_iframe_js(same_site_origin, response_queue_uuid));
+  const iframe_2_uuid = await receive(response_queue_uuid);
+
+  return [iframe_1_uuid, iframe_2_uuid];
+}
+
+promise_test(t => {
+  return new Promise(async (resolve, reject) => {
+    const response_queue_uuid = token();
+
+    const [iframe_1_uuid, iframe_2_uuid] =
+      await create_test_iframes(t, response_queue_uuid);
+
+    const channel_name = token();
+    const bc = new BroadcastChannel(channel_name);
+    bc.onmessage = resolve;
+
+    // Instruct the not-same-top-level-site iframe to send a message on the BC
+    // channel we are listening on. This message should not be received since
+    // the iframe should be in a different partition.
+    send(iframe_1_uuid,
+         bc_postmessage_js(channel_name, "iframe1 msg", response_queue_uuid));
+    if (await receive(response_queue_uuid) != "done") {
+      reject("Unable to trigger iframe1 BroadcastChannel message creation");
+    }
+
+    // Now instruct the same-top-level-site iframe to send a BC message. By
+    // the time we send the script to execute, have it send the BC message,
+    // and then receive the BC message in our BC instance, it should be
+    // reasonable to assume that the message from the first iframe would have
+    // been delivered if it was going to be.
+    send(iframe_2_uuid,
+         bc_postmessage_js(channel_name, "iframe2 msg", response_queue_uuid));
+    if (await receive(response_queue_uuid) != "done") {
+      reject("Unable to trigger iframe2 BroadcastChannel message creation");
+    }
+
+  }).then(event => {
+    assert_equals(event.data, "iframe2 msg");
+  });
+
+}, "BroadcastChannel messages aren't received from a cross-partition iframe");
+
+// Optional Test: Checking for partitioned BroadcastChannels in an A->B->A
+// (nested-iframe with cross-site ancestor chain) scenario.
+promise_test(t => {
+  return new Promise(async (resolve, reject) => {
+    const response_queue_uuid = token();
+
+    const [cross_site_iframe_uuid, all_same_parent_iframe_uuid] =
+      await create_test_iframes(t, response_queue_uuid);
+
+    // Create a same-origin iframe in a cross-site iframe in a same-site popup.
+    // Create the same-site child iframe of the cross-site iframe (A->B->A).
+    send(cross_site_iframe_uuid,
+         add_iframe_js(same_site_origin, response_queue_uuid));
+    const same_site_iframe_uuid = await receive(response_queue_uuid);
+
+    // Create a same-origin iframe in a same-site iframe in a same-site popup.
+    // Create the same-site child iframe of the same-site parent iframe (A->A->A).
+    send(all_same_parent_iframe_uuid,
+         add_iframe_js(same_site_origin, response_queue_uuid));
+    const all_same_child_iframe_uuid = await receive(response_queue_uuid);
+
+    const channel_name = token();
+    const bc = new BroadcastChannel(channel_name);
+    bc.onmessage = resolve;
+
+    // Instruct the A->B->A child iframe to send a message on the BC
+    // channel we are listening on. This message should not be received since
+    // the iframe should be in a different partition.
+    send(same_site_iframe_uuid,
+      bc_postmessage_js(channel_name, "iframe1 msg", response_queue_uuid));
+    if (await receive(response_queue_uuid) != "done") {
+      reject("Unable to trigger A->B->A BroadcastChannel message creation");
+    }
+
+    // Now instruct the A->A->A child iframe to send a BC message. By
+    // the time we send the script to execute, send the BC message,
+    // and receive the BC message in our BC instance, it should be
+    // reasonable to assume that the message from the first iframe would have
+    // been delivered if it was going to be.
+    send(all_same_child_iframe_uuid,
+      bc_postmessage_js(channel_name, "iframe2 msg", response_queue_uuid));
+    if (await receive(response_queue_uuid) != "done") {
+      reject("Unable to trigger A->A->A BroadcastChannel message creation");
+    }
+
+  }).then(event => {
+    assert_equals(event.data, "iframe2 msg");
+  });
+
+}, "BroadcastChannel messages aren't received from a nested iframe with a cross-site ancestor");
+
+const newWorker = (origin) => {
+  const worker_token = token();
+  const worker_url = origin + executor_worker_path + `&uuid=${worker_token}`;
+  const worker = new Worker(worker_url);
+  return worker_token;
+}
+
+promise_test(t => {
+  return new Promise(async (resolve, reject) => {
+    const response_queue_uuid = token();
+
+    const create_worker_js = (origin) => `
+      const importScript = ${importScript};
+      await importScript("/html/cross-origin-embedder-policy/credentialless" +
+                       "/resources/common.js");
+      await importScript("/html/anonymous-iframe/resources/common.js");
+      await importScript("/common/utils.js");
+      const newWorker = ${newWorker};
+      send("${response_queue_uuid}", newWorker("${origin}"));
+    `;
+
+    const [iframe_1_uuid, iframe_2_uuid] =
+      await create_test_iframes(t, response_queue_uuid);
+
+    // Create a dedicated worker in the cross-top-level-site iframe.
+    send(iframe_1_uuid, create_worker_js(same_site_origin));
+    const worker_1_uuid = await receive(response_queue_uuid);
+
+    // Create a dedicated worker in the same-top-level-site iframe.
+    send(iframe_2_uuid, create_worker_js(same_site_origin));
+    const worker_2_uuid = await receive(response_queue_uuid);
+
+    const channel_name = token();
+    const bc = new BroadcastChannel(channel_name);
+    bc.onmessage = async (e) => {
+      await send(worker_1_uuid, "self.close();");
+      await send(worker_2_uuid, "self.close();");
+      resolve(e);
+    };
+
+    // Instruct the not-same-top-level-site worker to send a message on the BC
+    // channel we are listening on. This message should not be received since
+    // the worker should be in a different partition.
+    send(worker_1_uuid,
+         bc_postmessage_js(channel_name, "worker1 msg", response_queue_uuid));
+    if (await receive(response_queue_uuid) != "done") {
+      reject("Unable to trigger worker1 BroadcastChannel message creation");
+    }
+
+    // Now instruct the same-top-level-site worker to send a BC message. By
+    // the time we send the script to execute, have it send the BC message,
+    // and then receive the BC message in our BC instance, it should be
+    // reasonable to assume that the message from the first worker would have
+    // been delivered if it was going to be.
+    send(worker_2_uuid,
+         bc_postmessage_js(channel_name, "worker2 msg", response_queue_uuid));
+    if (await receive(response_queue_uuid) != "done") {
+      reject("Unable to trigger worker2 BroadcastChannel message creation");
+    }
+
+  }).then(event => {
+    assert_equals(event.data, "worker2 msg");
+  });
+
+}, "BroadcastChannel messages aren't received from a cross-partition dedicated worker");
+
+const newSharedWorker = (origin) => {
+  const worker_token = token();
+  const worker_url = origin + executor_worker_path + `&uuid=${worker_token}`;
+  const worker = new SharedWorker(worker_url, worker_token);
+  return worker_token;
+}
+
+promise_test(t => {
+  return new Promise(async (resolve, reject) => {
+    const response_queue_uuid = token();
+
+    const create_worker_js = (origin) => `
+      const importScript = ${importScript};
+      await importScript("/html/cross-origin-embedder-policy/credentialless" +
+                       "/resources/common.js");
+      await importScript("/html/anonymous-iframe/resources/common.js");
+      await importScript("/common/utils.js");
+      const newSharedWorker = ${newSharedWorker};
+      send("${response_queue_uuid}", newSharedWorker("${origin}"));
+    `;
+
+    const [iframe_1_uuid, iframe_2_uuid] =
+      await create_test_iframes(t, response_queue_uuid);
+
+    // Create a shared worker in the cross-top-level-site iframe.
+    send(iframe_1_uuid, create_worker_js(same_site_origin));
+    const worker_1_uuid = await receive(response_queue_uuid);
+
+    // Create a shared worker in the same-top-level-site iframe.
+    send(iframe_2_uuid, create_worker_js(same_site_origin));
+    const worker_2_uuid = await receive(response_queue_uuid);
+
+    const channel_name = token();
+    const bc = new BroadcastChannel(channel_name);
+    bc.onmessage = async (e) => {
+      await send(worker_1_uuid, "self.close();");
+      await send(worker_2_uuid, "self.close();");
+      resolve(e);
+    };
+
+    // Instruct the not-same-top-level-site worker to send a message on the BC
+    // channel we are listening on. This message should not be received since
+    // the worker should be in a different partition.
+    send(worker_1_uuid,
+         bc_postmessage_js(channel_name, "worker1 msg", response_queue_uuid));
+    if (await receive(response_queue_uuid) != "done") {
+      reject("Unable to trigger worker1 BroadcastChannel message creation");
+    }
+
+    // Now instruct the same-top-level-site worker to send a BC message. By
+    // the time we send the script to execute, have it send the BC message,
+    // and then receive the BC message in our BC instance, it should be
+    // reasonable to assume that the message from the first worker would have
+    // been delivered if it was going to be.
+    send(worker_2_uuid,
+         bc_postmessage_js(channel_name, "worker2 msg", response_queue_uuid));
+    if (await receive(response_queue_uuid) != "done") {
+      reject("Unable to trigger worker2 BroadcastChannel message creation");
+    }
+
+  }).then(event => {
+    assert_equals(event.data, "worker2 msg");
+  });
+
+}, "BroadcastChannel messages aren't received from a cross-partition shared worker");
+
+const newServiceWorker = async (origin) => {
+  const worker_token = token();
+  const worker_url = origin + executor_service_worker_path +
+                     `&uuid=${worker_token}`;
+  const worker_url_path = executor_service_worker_path.substring(0,
+                              executor_service_worker_path.lastIndexOf('/'));
+  const scope = worker_url_path + "/not-used/";
+  const reg = await navigator.serviceWorker.register(worker_url,
+                                                     {'scope': scope});
+  return worker_token;
+}
+
+promise_test(t => {
+  return new Promise(async (resolve, reject) => {
+    const response_queue_uuid = token();
+
+    const create_worker_js = (origin) => `
+      const importScript = ${importScript};
+      await importScript("/html/cross-origin-embedder-policy/credentialless" +
+                       "/resources/common.js");
+      await importScript("/html/anonymous-iframe/resources/common.js");
+      await importScript("/common/utils.js");
+      const newServiceWorker = ${newServiceWorker};
+      send("${response_queue_uuid}", await newServiceWorker("${origin}"));
+    `;
+
+    const [iframe_1_uuid, iframe_2_uuid] =
+      await create_test_iframes(t, response_queue_uuid);
+
+    // Create a service worker in the cross-top-level-site iframe.
+    send(iframe_1_uuid, create_worker_js(same_site_origin));
+    var worker_1_uuid = await receive(response_queue_uuid);
+
+    const channel_name = token();
+    const bc = new BroadcastChannel(channel_name);
+    bc.onmessage = async (e) => {
+      if (worker_1_uuid) {
+        await send(worker_1_uuid, "self.registration.unregister();");
+      }
+      if (worker_2_uuid) {
+        await send(worker_2_uuid, "self.registration.unregister();");
+      }
+      resolve(e);
+    };
+
+    // Instruct the not-same-top-level-site worker to send a message on the BC
+    // channel we are listening on. This message should not be received since
+    // the worker should be in a different partition.
+    send(worker_1_uuid,
+         bc_postmessage_js(channel_name, "worker1 msg", response_queue_uuid));
+    if (await receive(response_queue_uuid) != "done") {
+      reject("Unable to trigger worker1 BroadcastChannel message creation");
+    }
+
+    await send(worker_1_uuid, "await self.registration.unregister();");
+    worker_1_uuid = undefined;
+
+    // Create a service worker in the same-top-level-site iframe. Note that
+    // if service workers are unpartitioned then this new service worker would
+    // replace the one created above. This is why we wait to create the second
+    // service worker until after we are done with the first one.
+    send(iframe_2_uuid, create_worker_js(same_site_origin));
+    var worker_2_uuid = await receive(response_queue_uuid);
+
+    // Now instruct the same-top-level-site worker to send a BC message. By
+    // the time we send the script to execute, have it send the BC message,
+    // and then receive the BC message in our BC instance, it should be
+    // reasonable to assume that the message from the first worker would have
+    // been delivered if it was going to be.
+    send(worker_2_uuid,
+         bc_postmessage_js(channel_name, "worker2 msg", response_queue_uuid));
+    if (await receive(response_queue_uuid) != "done") {
+      reject("Unable to trigger worker2 BroadcastChannel message creation");
+    }
+
+    await send(worker_2_uuid, "await self.registration.unregister();");
+    worker_2_uuid = undefined;
+
+  }).then(event => {
+    assert_equals(event.data, "worker2 msg");
+  });
+
+}, "BroadcastChannel messages aren't received from a cross-partition service worker");
+
+</script>
+</body>
diff --git a/testing/web-platform/tests/webmessaging/broadcastchannel/detached-iframe.html b/testing/web-platform/tests/webmessaging/broadcastchannel/detached-iframe.html
new file mode 100644
index 0000000000..b9b06c3a46
--- /dev/null
+++ b/testing/web-platform/tests/webmessaging/broadcastchannel/detached-iframe.html
@@ -0,0 +1,174 @@
+<!DOCTYPE html>
+<meta charset=utf-8>
+<script src="/resources/testharness.js"></script>
+<script src="/resources/testharnessreport.js"></script>
+<script src="/common/get-host-info.sub.js"></script>
+<!-- Pull in the with_iframe helper function from the service worker tests -->
+<script src="/service-workers/service-worker/resources/test-helpers.sub.js"></script>
+<body>
+<script>
+const TEST_IFRAME_CLASS_NAME = 'test-iframe';
+const events = [];
+var bc1;
+const DONE_MSG = 'done';
+
+function DetachedIframeTestCheckForOneMessage(t) {
+  return new Promise((resolve) => {
+    bc1.onmessage = t.step_func(e => {
+      events.push(e);
+      if (e.data == DONE_MSG) {
+        assert_equals(events.length, 1);
+        resolve();
+      }
+    });
+  });
+}
+
+const IframeAction = {
+  REMOVE_BEFORE_CREATION: 'remove-before-creation',
+  REMOVE_AFTER_CREATION: 'remove-after-creation',
+};
+
+async function doMessageSentTest(t, channelName, action) {
+  await with_iframe('about:blank');
+  const iframe = document.getElementsByClassName(TEST_IFRAME_CLASS_NAME)[0];
+  const iframe_BroadcastChannel = iframe.contentWindow.BroadcastChannel;
+
+  if (action === IframeAction.REMOVE_BEFORE_CREATION) {
+    iframe.remove();
+  }
+
+  events.length = 0;
+
+  bc1 = new BroadcastChannel(channelName);
+  const bc2 = new BroadcastChannel(channelName);
+  const iframe_bc = new iframe_BroadcastChannel(channelName);
+
+  if (action === IframeAction.REMOVE_AFTER_CREATION) {
+    iframe.remove();
+  }
+
+  const testResultsPromise = DetachedIframeTestCheckForOneMessage(t);
+
+  iframe_bc.postMessage('test');
+  bc2.postMessage(DONE_MSG);
+
+  bc2.close();
+  iframe_bc.close();
+  t.add_cleanup(() => bc1.close());
+
+  return testResultsPromise;
+}
+
+promise_test(async t => {
+  return doMessageSentTest(
+      t, 'postMessage-from-detached-iframe-pre',
+      IframeAction.REMOVE_AFTER_CREATION);
+}, 'BroadcastChannel messages from detached iframe to parent should be ignored (BC created before detaching)');
+
+promise_test(async t => {
+  return doMessageSentTest(
+      t, 'postMessage-from-detached-iframe-post',
+      IframeAction.REMOVE_BEFORE_CREATION);
+}, 'BroadcastChannel messages from detached iframe to parent should be ignored (BC created after detaching)');
+
+
+async function doMessageReceivedTest(t, channelName, action) {
+  await with_iframe('about:blank');
+  const iframe = document.getElementsByClassName(TEST_IFRAME_CLASS_NAME)[0];
+  const iframe_BroadcastChannel = iframe.contentWindow.BroadcastChannel;
+
+  if (action === IframeAction.REMOVE_BEFORE_CREATION) {
+    iframe.remove();
+  }
+
+  events.length = 0;
+
+  // `iframe_bc` must be created first so that it receives messages before
+  // `bc1`. That way we can tell whether `iframe_bc` received a message by
+  // inspecting `events` in the `bc1` message handler.
+  const iframe_bc = new iframe_BroadcastChannel(channelName);
+  iframe_bc.onmessage = e => {
+    events.push(e)
+  };
+  bc1 = new BroadcastChannel(channelName);
+  const bc2 = new BroadcastChannel(channelName);
+
+  if (action === IframeAction.REMOVE_AFTER_CREATION) {
+    iframe.remove();
+  }
+
+  const testResultsPromise = DetachedIframeTestCheckForOneMessage(t);
+  bc2.postMessage(DONE_MSG);
+
+  bc2.close();
+  iframe_bc.close();
+  t.add_cleanup(() => bc1.close());
+}
+
+promise_test(async t => {
+  return doMessageReceivedTest(
+      t, 'postMessage-to-detached-iframe-pre',
+      IframeAction.REMOVE_AFTER_CREATION);
+}, 'BroadcastChannel messages from parent to detached iframe should be ignored (BC created before detaching)');
+
+promise_test(async t => {
+  return doMessageReceivedTest(
+      t, 'postMessage-to-detached-iframe-post',
+      IframeAction.REMOVE_BEFORE_CREATION);
+}, 'BroadcastChannel messages from parent to detached iframe should be ignored (BC created after detaching)');
+
+
+async function doMessageSendReceiveTest(t, channelName, action) {
+  await with_iframe('about:blank');
+  const iframe = document.getElementsByClassName(TEST_IFRAME_CLASS_NAME)[0];
+  const iframe_BroadcastChannel = iframe.contentWindow.BroadcastChannel;
+
+  if (action === IframeAction.REMOVE_BEFORE_CREATION) {
+    iframe.remove();
+  }
+
+  const iframe_bc1 = new iframe_BroadcastChannel(channelName);
+  const iframe_bc2 = new iframe_BroadcastChannel(channelName);
+  iframe_bc1.onmessage = t.unreached_func(
+      'Detached iframe BroadcastChannel instance received message unexpectedly');
+
+  if (action === IframeAction.REMOVE_AFTER_CREATION) {
+    iframe.remove();
+  }
+
+  iframe_bc2.postMessage(DONE_MSG);
+
+  iframe_bc2.close();
+  t.add_cleanup(() => iframe_bc1.close());
+
+  // To avoid calling t.step_timeout here, instead just create two new
+  // BroadcastChannel instances and complete the test when a message is passed
+  // between them.  Per the spec, all "BroadcastChannel objects whose relevant
+  // agents are the same" must have messages delivered to them in creation
+  // order, so if we get this message then it's safe to assume the earlier
+  // message would have been delivered if it was going to be.
+  const bc1 = new BroadcastChannel(channelName);
+  const bc2 = new BroadcastChannel(channelName);
+  return new Promise((resolve) => {
+    bc1.onmessage = t.step_func(e => {
+      resolve();
+    });
+    bc2.postMessage(DONE_MSG);
+  });
+}
+
+promise_test(async t => {
+  return doMessageSendReceiveTest(
+      t, 'postMessage-within-detached-iframe-pre',
+      IframeAction.REMOVE_AFTER_CREATION);
+}, 'BroadcastChannel messages within detached iframe should be ignored (BCs created before detaching)');
+
+promise_test(async t => {
+  return doMessageSendReceiveTest(
+      t, 'postMessage-within-detached-iframe-post',
+      IframeAction.REMOVE_BEFORE_CREATION);
+}, 'BroadcastChannel messages within detached iframe should be ignored (BCs created after detaching)');
+
+</script>
+</body>
diff --git a/testing/web-platform/tests/webmessaging/broadcastchannel/interface.any.js b/testing/web-platform/tests/webmessaging/broadcastchannel/interface.any.js
new file mode 100644
index 0000000000..35e09d34b4
--- /dev/null
+++ b/testing/web-platform/tests/webmessaging/broadcastchannel/interface.any.js
@@ -0,0 +1,65 @@
+test(() => assert_throws_js(TypeError, () => new BroadcastChannel()),
+  'Should throw if no name is provided');
+
+test(() => {
+    let c = new BroadcastChannel(null);
+    assert_equals(c.name, 'null');
+  }, 'Null name should not throw');
+
+test(() => {
+    let c = new BroadcastChannel(undefined);
+    assert_equals(c.name, 'undefined');
+  }, 'Undefined name should not throw');
+
+test(() => {
+    let c = new BroadcastChannel('fooBar');
+    assert_equals(c.name, 'fooBar');
+  }, 'Non-empty name should not throw');
+
+test(() => {
+    let c = new BroadcastChannel(123);
+    assert_equals(c.name, '123');
+  }, 'Non-string name should not throw');
+
+test(() => {
+    let c = new BroadcastChannel('');
+    assert_throws_js(TypeError, () => c.postMessage());
+  }, 'postMessage without parameters should throw');
+
+test(() => {
+    let c = new BroadcastChannel('');
+    c.postMessage(null);
+  }, 'postMessage with null should not throw');
+
+test(() => {
+    let c = new BroadcastChannel('');
+    c.close();
+  }, 'close should not throw');
+
+test(() => {
+    let c = new BroadcastChannel('');
+    c.close();
+    c.close();
+  }, 'close should not throw when called multiple times');
+
+test(() => {
+    let c = new BroadcastChannel('');
+    c.close();
+    assert_throws_dom('InvalidStateError', () => c.postMessage(''));
+  }, 'postMessage after close should throw');
+
+test(() => {
+    let c = new BroadcastChannel('');
+    assert_not_equals(c.onmessage, undefined);
+  }, 'BroadcastChannel should have an onmessage event');
+
+test(() => {
+    let c = new BroadcastChannel('');
+    assert_throws_dom('DataCloneError', () => c.postMessage(Symbol()));
+  }, 'postMessage should throw with uncloneable data');
+
+test(() => {
+    let c = new BroadcastChannel('');
+    c.close();
+    assert_throws_dom('InvalidStateError', () => c.postMessage(Symbol()));
+  }, 'postMessage should throw InvalidStateError after close, even with uncloneable data');
diff --git a/testing/web-platform/tests/webmessaging/broadcastchannel/opaque-origin.html b/testing/web-platform/tests/webmessaging/broadcastchannel/opaque-origin.html
new file mode 100644
index 0000000000..e09d935244
--- /dev/null
+++ b/testing/web-platform/tests/webmessaging/broadcastchannel/opaque-origin.html
@@ -0,0 +1,193 @@
+<!doctype html>
+<html>
+<head>
+<meta charset=utf-8>
+<meta name="timeout" content="long">
+<title></title>
+<script src=/resources/testharness.js></script>
+<script src=/resources/testharnessreport.js></script>
+</head>
+<body>
+<script>
+<!--
+promise_test(t => {
+  return new Promise((resolve) => {
+    let ifr = document.createElement("iframe");
+    ifr.src =
+      "data:text/html,<script> let bc = new BroadcastChannel(\"test\");" +
+      "bc.onmessage = (e) => {" +
+      "  if (e.data == \"ping\") bc.postMessage('pong');"+
+      "  else parent.postMessage({workerMessageOrigin: e.data, messageOrigin: e.origin}, \"*\"); };" +
+      "new Worker(URL.createObjectURL(new Blob([\"" +
+      "let bc2 = new BroadcastChannel('test'); bc2.postMessage('ping'); " +
+      "bc2.onmessage = e => bc2.postMessage(e.origin);" +
+      "\"], {type: 'text/javascript'}))); </script>";
+    window.addEventListener("message", t.step_func(e => {
+        assert_equals(e.data.workerMessageOrigin, "null");
+        assert_equals(e.data.messageOrigin, "null");
+        resolve();
+      }), {once: true});
+    t.add_cleanup(() => { document.body.removeChild(ifr) });
+    document.body.appendChild(ifr);
+    });
+}, "Opaque origin should be serialized to \"null\"");
+
+
+const iframe_src = (channel_name, iframe_name) => `data:text/html,<script>
+let bc2 = new BroadcastChannel("${channel_name}");
+bc2.onmessage = (e) => {
+  if (e.data == "from-${iframe_name}") {
+    parent.postMessage("${iframe_name}-done", "*");
+  } else {
+    parent.postMessage("fail", "*");
+  }
+};
+let bc3 = new BroadcastChannel("${channel_name}");
+bc3.postMessage("from-${iframe_name}");
+</script>`;
+
+promise_test(t => {
+  return new Promise((resolve, reject) => {
+    const channel_name = "opaque-origin-test-2";
+    const bc1 = new BroadcastChannel(channel_name);
+    bc1.onmessage = t.unreached_func("Received message from an opaque origin");
+
+    // We'll create an iframe and have it send a BroadcastChannel message
+    // between two instances. Once the message is received, it will postMessage
+    // back and we'll repeat this with another iframe. If the first
+    // BroadcastChannel message is received by `bc1`, or if the second
+    // BroadcastChannel message is received by `bc1` or `bc2` in the first
+    // iframe, then the test should fail.
+
+    window.addEventListener("message", e => {
+      if(e.data == "iframe1-done") {
+        let iframe2 = document.createElement("iframe");
+        iframe2.src = iframe_src(channel_name, "iframe2");
+        t.add_cleanup(() => { document.body.removeChild(iframe2) });
+        document.body.appendChild(iframe2);
+      } else if(e.data == "iframe2-done") {
+        resolve();
+      } else if(e.data == "fail") {
+        reject("One opaque origin received a message from the other");
+      } else {
+        reject("An unexpected error occurred");
+      }
+    });
+
+    let iframe1 = document.createElement("iframe");
+    iframe1.src = iframe_src(channel_name, "iframe1");
+    t.add_cleanup(() => { document.body.removeChild(iframe1) });
+    document.body.appendChild(iframe1);
+    });
+}, "BroadcastChannel messages from opaque origins should be self-contained");
+
+const data_url_worker_src = (channel_name, worker_name) => {
+  const source = `
+const handler = (reply) => {
+  let bc2 = new BroadcastChannel("${channel_name}");
+  bc2.onmessage = (e) => {
+    if (e.data == "from-${worker_name}") {
+      reply("${worker_name}-done");
+    } else {
+      reply("fail");
+    }
+  };
+  let bc3 = new BroadcastChannel("${channel_name}");
+  bc3.postMessage("from-${worker_name}");
+};
+// For dedicated workers:
+self.addEventListener("message", () => handler(self.postMessage));
+// For shared workers:
+self.addEventListener("connect", (e) => {
+  var port = e.ports[0];
+  port.onmessage = () => handler(msg => port.postMessage(msg));
+  port.start();
+
+});
+`;
+  return "data:,".concat(encodeURIComponent(source));
+}
+
+promise_test(t => {
+  return new Promise((resolve, reject) => {
+    const channel_name = "opaque-origin-test-3";
+    const bc1 = new BroadcastChannel(channel_name);
+    bc1.onmessage = e => { reject("Received message from an opaque origin"); };
+
+    // Same as the previous test but with data URL dedicated workers (which
+    // should have opaque origins per the HTML spec).
+    const worker_name_prefix = "data-url-dedicated-worker";
+    const worker_1_name = `${worker_name_prefix}-1`;
+    const worker_2_name = `${worker_name_prefix}-2`;
+
+    const handler = e => {
+      if(e.data == `${worker_1_name}-done`) {
+        const worker2 = new Worker(data_url_worker_src(channel_name, worker_2_name));
+        t.add_cleanup(() => worker2.terminate());
+        worker2.addEventListener("message", handler);
+        worker2.postMessage("go!");
+      } else if(e.data == `${worker_2_name}-done`) {
+        resolve();
+      } else if(e.data == "fail") {
+        reject("One opaque origin received a message from the other");
+      } else {
+        reject("An unexpected error occurred");
+      }
+    };
+
+    let worker1 = new Worker(data_url_worker_src(channel_name, worker_1_name));
+    t.add_cleanup(() => worker1.terminate());
+    worker1.addEventListener("message", handler);
+    worker1.postMessage("go!");
+    });
+}, "BroadcastChannel messages from data URL dedicated workers should be self-contained");
+
+promise_test(() => {
+  return new Promise((resolve, reject) => {
+    const channel_name = "opaque-origin-test-4";
+    const bc1 = new BroadcastChannel(channel_name);
+
+    // Same as the previous test but with data URL shared workers (which
+    // should have opaque origins per the HTML spec).
+    const worker_name_prefix = "data-url-shared-worker";
+    const worker_1_name = `${worker_name_prefix}-1`;
+    const worker_2_name = `${worker_name_prefix}-2`;
+
+    const handler = e => {
+      if (e.data == `${worker_1_name}-done`) {
+        const worker_script = data_url_worker_src(channel_name, worker_2_name);
+        const worker2 = new SharedWorker(worker_script, worker_2_name);
+        worker2.port.addEventListener("message", handler);
+        worker2.port.start();
+        worker2.port.postMessage("go!");
+      } else if(e.data == `${worker_2_name}-done`) {
+        resolve();
+      } else if(e.data == "fail") {
+        reject("One opaque origin received a message from the other");
+      } else {
+        reject("An unexpected error occurred");
+      }
+    };
+
+    bc1.onmessage = e => {
+      if (e.data == "go!") {
+        const worker_script = data_url_worker_src(channel_name, worker_1_name);
+        const worker1 = new SharedWorker(worker_script, worker_1_name);
+        worker1.port.addEventListener("message", handler);
+        worker1.port.start();
+        worker1.port.postMessage("go!");
+      } else {
+        reject("Received message from an opaque origin");
+      }
+    };
+
+    // Ensure that the BroadcastChannel instance above can receive messages
+    // before we create the first shared worker.
+    const bc2 = new BroadcastChannel(channel_name);
+    bc2.postMessage("go!");
+    });
+}, "BroadcastChannel messages from data URL shared workers should be self-contained");
+//-->
+</script>
+</body>
+</html>
diff --git a/testing/web-platform/tests/webmessaging/broadcastchannel/ordering.html b/testing/web-platform/tests/webmessaging/broadcastchannel/ordering.html
new file mode 100644
index 0000000000..2d521b9e0c
--- /dev/null
+++ b/testing/web-platform/tests/webmessaging/broadcastchannel/ordering.html
@@ -0,0 +1,116 @@
+<!DOCTYPE html>
+<meta charset=utf-8>
+<script src="/resources/testharness.js"></script>
+<script src="/resources/testharnessreport.js"></script>
+<!-- Pull in the with_iframe helper function from the service worker tests -->
+<script src="/service-workers/service-worker/resources/test-helpers.sub.js"></script>
+<body>
+<script>
+
+const BC0_FIRST_MSG = 'from BC0 - first';
+const BC1_FIRST_MSG = 'from BC1 - first';
+const BC2_FIRST_MSG = 'from BC2 - first';
+const BC3_FIRST_MSG = 'from BC3 - first';
+const BC0_SECOND_MSG = 'from BC0 - second';
+const BC1_SECOND_MSG = 'from BC1 - second';
+const BC2_SECOND_MSG = 'from BC2 - second';
+const BC3_SECOND_MSG = 'done';
+const BC0_TARGET_NAME = 'BC1';
+const BC1_TARGET_NAME = 'BC1';
+const BC2_TARGET_NAME = 'BC2';
+const BC3_TARGET_NAME = 'BC3';
+const MULTI_FRAME_ORDERING_TEST_CHANNEL_NAME = 'multi-frame-order';
+
+const bc0 = new BroadcastChannel(MULTI_FRAME_ORDERING_TEST_CHANNEL_NAME);
+const messages = [];
+
+function logReceivedMessage(targetname, e) {
+  messages.push({'target': targetname, 'data': e.data});
+}
+
+function postMessagesToChannel() {
+  return new Promise((resolve) => {
+    bc0.postMessage(BC0_FIRST_MSG);
+    bc0.postMessage(BC0_SECOND_MSG);
+    resolve();
+  });
+}
+
+// Expected flow of messages between the BroadcastChannel objects (based on
+// the requirement that messages get delivered to BroadcastChannel objects
+// "in creation order, oldest first") and comments describing the actions
+// taken in response to each event
+const EXPECTED_RESULTS = [
+  // -> BC0 sends two messages, BC1 and BC2 are connected to the channel
+
+  {'data': BC0_FIRST_MSG, 'target': BC1_TARGET_NAME},
+  // -> BC1 Creates BC3 and sends first message
+
+  {'data': BC0_FIRST_MSG, 'target': BC2_TARGET_NAME},
+  // -> BC2 sends two messages
+
+  // BC3 isn't expected to receive the messages sent before it was created, so
+  // no corresponding entries here for messages from BC0.
+
+  {'data': BC0_SECOND_MSG, 'target': BC1_TARGET_NAME},
+  // -> BC1 sends second message
+
+  {'data': BC0_SECOND_MSG, 'target': BC2_TARGET_NAME},
+  // -> BC2 closes
+
+  {'data': BC1_FIRST_MSG, 'target': BC0_TARGET_NAME},
+
+  {'data': BC1_FIRST_MSG, 'target': BC3_TARGET_NAME},
+  // -> BC3 sends first message
+
+  {'data': BC2_FIRST_MSG, 'target': BC0_TARGET_NAME},
+
+  {'data': BC2_FIRST_MSG, 'target': BC1_TARGET_NAME},
+  // -> BC1 closes
+
+  {'data': BC2_FIRST_MSG, 'target': BC3_TARGET_NAME},
+  // -> BC3 sends second message
+
+  {'data': BC2_SECOND_MSG, 'target': BC0_TARGET_NAME},
+
+  {'data': BC2_SECOND_MSG, 'target': BC3_TARGET_NAME},
+  // -> BC3 closes
+
+  {'data': BC1_SECOND_MSG, 'target': BC0_TARGET_NAME},
+
+  {'data': BC3_FIRST_MSG, 'target': BC0_TARGET_NAME},
+
+  {'data': BC3_SECOND_MSG, 'target': BC0_TARGET_NAME},
+];
+
+function testCompletion(t) {
+  return new Promise((resolve) => {
+    bc0.onmessage = t.step_func(e => {
+      logReceivedMessage(BC0_TARGET_NAME, e);
+      if (e.data == BC3_SECOND_MSG) {
+        assert_equals(messages.length, EXPECTED_RESULTS.length);
+        for(var i = 0; i < messages.length; i++) {
+          assert_equals(messages[i].target, EXPECTED_RESULTS[i].target, `Message ${i+1} has unexpected target`);
+          assert_equals(messages[i].data, EXPECTED_RESULTS[i].data, `Message ${i+1} has unexpected message contents`);
+        }
+        resolve();
+      }
+    });
+  });
+}
+
+promise_test(async t => {
+
+  const testResults = testCompletion(t);
+  // Await them sequentially because we need the BroadcastChannel object in
+  // iframe1 to be created first, we need the BroadcastChannel object in
+  // iframe2 to be created second, and then we only want to call
+  // postMessagesToChannel once both BroadcastChannels have been created.
+  await with_iframe('resources/ordering.html?id=iframe1');
+  await with_iframe('resources/ordering.html?id=iframe2');
+  await postMessagesToChannel();
+  return testResults;
+}, "Messages are delivered in port creation order across multiple frames");
+
+</script>
+</body>
diff --git a/testing/web-platform/tests/webmessaging/broadcastchannel/origin.window.js b/testing/web-platform/tests/webmessaging/broadcastchannel/origin.window.js
new file mode 100644
index 0000000000..7e9d602af1
--- /dev/null
+++ b/testing/web-platform/tests/webmessaging/broadcastchannel/origin.window.js
@@ -0,0 +1,10 @@
+async_test(t => {
+  const crossOriginURL = new URL("resources/origin.html", self.location.href).href.replace("://", "://天気の良い日."),
+        frame = document.createElement("iframe");
+  frame.src = crossOriginURL;
+  document.body.appendChild(frame);
+  t.add_cleanup(() => frame.remove());
+  self.onmessage = t.step_func_done(e => {
+    assert_equals(e.data, self.origin.replace("://", "://xn--n8j6ds53lwwkrqhv28a."));
+  });
+}, "Serialization of BroadcastChannel origin");
diff --git a/testing/web-platform/tests/webmessaging/broadcastchannel/resources/cross-origin.html b/testing/web-platform/tests/webmessaging/broadcastchannel/resources/cross-origin.html
new file mode 100644
index 0000000000..5078b6fc8e
--- /dev/null
+++ b/testing/web-platform/tests/webmessaging/broadcastchannel/resources/cross-origin.html
@@ -0,0 +1,15 @@
+<body></body>
+<script>
+  window.onload = function() {
+    bc1 = new BroadcastChannel('no-cross-origin-messages');
+    bc2 = new BroadcastChannel('no-cross-origin-messages');
+    bc2.onmessage = e => {
+      parent.postMessage('done', "*");
+    };
+    // Post a message on bc1 and once we receive it in bc2, we know that the
+    // message should have been sent to bc0 if messages were being passed
+    // across origin (assuming compliance with the spec regarding message
+    // delivery in port creation order).
+    bc1.postMessage('ignition');
+  }
+</script>
diff --git a/testing/web-platform/tests/webmessaging/broadcastchannel/resources/ordering.html b/testing/web-platform/tests/webmessaging/broadcastchannel/resources/ordering.html
new file mode 100644
index 0000000000..b7f12d865a
--- /dev/null
+++ b/testing/web-platform/tests/webmessaging/broadcastchannel/resources/ordering.html
@@ -0,0 +1,78 @@
+<body></body>
+<script>
+  const BC0_FIRST_MSG = 'from BC0 - first';
+  const BC1_FIRST_MSG = 'from BC1 - first';
+  const BC2_FIRST_MSG = 'from BC2 - first';
+  const BC3_FIRST_MSG = 'from BC3 - first';
+  const BC0_SECOND_MSG = 'from BC0 - second';
+  const BC1_SECOND_MSG = 'from BC1 - second';
+  const BC2_SECOND_MSG = 'from BC2 - second';
+  const BC3_SECOND_MSG = 'done';
+  const BC0_TARGET_NAME = 'BC1';
+  const BC1_TARGET_NAME = 'BC1';
+  const BC2_TARGET_NAME = 'BC2';
+  const BC3_TARGET_NAME = 'BC3';
+  const MULTI_FRAME_ORDERING_TEST_CHANNEL_NAME = 'multi-frame-order';
+
+  var bc1, bc2, bc3;
+  var sentMessageCountForBc1 = 0;
+  var sentMessageCountForBc2 = 0;
+  var sentMessageCountForBc3 = 0;
+
+  var bc1_handler = e => {
+    window.top.logReceivedMessage(BC1_TARGET_NAME, e);
+    switch(sentMessageCountForBc1) {
+      case 0:
+        bc3 = new BroadcastChannel(MULTI_FRAME_ORDERING_TEST_CHANNEL_NAME);
+        bc3.onmessage = bc3_handler;
+        bc1.postMessage(BC1_FIRST_MSG);
+        break;
+      case 1:
+        bc1.postMessage(BC1_SECOND_MSG);
+        break;
+      case 2:
+        bc1.close();
+        return;
+    }
+    sentMessageCountForBc1 += 1;
+  }
+  var bc2_handler = e => {
+    window.top.logReceivedMessage(BC2_TARGET_NAME, e);
+    switch(sentMessageCountForBc2) {
+      case 0:
+        bc2.postMessage(BC2_FIRST_MSG);
+        bc2.postMessage(BC2_SECOND_MSG);
+        sentMessageCountForBc2 += 2;
+        break;
+      case 2:
+        bc2.close();
+        return;
+    }
+  };
+  var bc3_handler = e => {
+    window.top.logReceivedMessage(BC3_TARGET_NAME, e);
+    switch(sentMessageCountForBc3) {
+      case 0:
+        bc3.postMessage(BC3_FIRST_MSG);
+        break;
+      case 1:
+        bc3.postMessage(BC3_SECOND_MSG);
+        break;
+      case 2:
+        bc3.close();
+        return;
+    }
+    sentMessageCountForBc3 += 1;
+  };
+
+  window.onload = function() {
+    const params = new URLSearchParams(window.location.search);
+    if (params.get('id') === 'iframe1') {
+      bc1 = new BroadcastChannel(MULTI_FRAME_ORDERING_TEST_CHANNEL_NAME);
+      bc1.onmessage = bc1_handler;
+    } else if (params.get('id')  === 'iframe2') {
+      bc2 = new BroadcastChannel(MULTI_FRAME_ORDERING_TEST_CHANNEL_NAME);
+      bc2.onmessage = bc2_handler;
+    }
+  }
+</script>
diff --git a/testing/web-platform/tests/webmessaging/broadcastchannel/resources/origin.html b/testing/web-platform/tests/webmessaging/broadcastchannel/resources/origin.html
new file mode 100644
index 0000000000..f57d582bbb
--- /dev/null
+++ b/testing/web-platform/tests/webmessaging/broadcastchannel/resources/origin.html
@@ -0,0 +1,8 @@
+<script>
+const bc1 = new BroadcastChannel("ladila"),
+      bc2 = new BroadcastChannel("ladila");
+bc2.onmessage = e => {
+  parent.postMessage(e.origin, "*");
+}
+bc1.postMessage("does not matter");
+</script>
diff --git a/testing/web-platform/tests/webmessaging/broadcastchannel/resources/sandboxed.html b/testing/web-platform/tests/webmessaging/broadcastchannel/resources/sandboxed.html
new file mode 100644
index 0000000000..e32962cdfd
--- /dev/null
+++ b/testing/web-platform/tests/webmessaging/broadcastchannel/resources/sandboxed.html
@@ -0,0 +1,10 @@
+<!DOCTYPE html>
+<meta charset=utf-8>
+<script>
+try {
+  let c = new BroadcastChannel('foo');
+  parent.postMessage('Created', '*');
+} catch (e) {
+  parent.postMessage('Exception: ' + e.name, '*');
+}
+</script>
diff --git a/testing/web-platform/tests/webmessaging/broadcastchannel/resources/service-worker.js b/testing/web-platform/tests/webmessaging/broadcastchannel/resources/service-worker.js
new file mode 100644
index 0000000000..a3d17b9c65
--- /dev/null
+++ b/testing/web-platform/tests/webmessaging/broadcastchannel/resources/service-worker.js
@@ -0,0 +1,15 @@
+let promise_func = null;
+let promise = new Promise(resolve => promise_func = resolve);
+
+const SERVICE_WORKER_TEST_CHANNEL_NAME = 'service worker';
+const bc3 = new BroadcastChannel(SERVICE_WORKER_TEST_CHANNEL_NAME);
+bc3.onmessage = e => {
+  bc3.postMessage('done');
+  promise_func();
+};
+bc3.postMessage('from worker');
+
+// Ensure that the worker stays alive for the duration of the test
+self.addEventListener('install', evt => {
+  evt.waitUntil(promise);
+});
diff --git a/testing/web-platform/tests/webmessaging/broadcastchannel/resources/worker.js b/testing/web-platform/tests/webmessaging/broadcastchannel/resources/worker.js
new file mode 100644
index 0000000000..ee2d51a254
--- /dev/null
+++ b/testing/web-platform/tests/webmessaging/broadcastchannel/resources/worker.js
@@ -0,0 +1,37 @@
+importScripts("/common/gc.js");
+
+var c;
+
+async function handler(e, reply) {
+  if (e.data.ping) {
+    c.postMessage(e.data.ping);
+    return;
+  }
+  if (e.data.blob) {
+    (() => {
+      c.postMessage({blob: new Blob(e.data.blob)});
+    })();
+    await garbageCollect();
+  }
+  c = new BroadcastChannel(e.data.channel);
+  let messages = [];
+  c.onmessage = e => {
+      if (e.data === 'ready') {
+        // Ignore any 'ready' messages from the other thread since there could
+        // be some race conditions between this BroadcastChannel instance
+        // being created / ready to receive messages and the message being sent.
+        return;
+      }
+      messages.push(e.data);
+      if (e.data == 'done')
+        reply(messages);
+    };
+  c.postMessage('from worker');
+}
+
+onmessage = e => handler(e, postMessage);
+
+onconnect = e => {
+  let port = e.ports[0];
+  port.onmessage = e => handler(e, msg => port.postMessage(msg));
+};
diff --git a/testing/web-platform/tests/webmessaging/broadcastchannel/sandbox.html b/testing/web-platform/tests/webmessaging/broadcastchannel/sandbox.html
new file mode 100644
index 0000000000..aedf3c0d6f
--- /dev/null
+++ b/testing/web-platform/tests/webmessaging/broadcastchannel/sandbox.html
@@ -0,0 +1,16 @@
+<!DOCTYPE html>
+<meta charset=utf-8>
+<title>Creating BroadcastChannel in an opaque origin</title>
+<script src="/resources/testharness.js"></script>
+<script src="/resources/testharnessreport.js"></script>
+<body>
+<script>
+async_test(t => {
+    self.onmessage = t.step_func(e => {
+        assert_equals(e.data, 'Created');
+        t.done();
+      });
+  });
+</script>
+<iframe sandbox="allow-scripts" src="resources/sandboxed.html"></iframe>
+</body>
diff --git a/testing/web-platform/tests/webmessaging/broadcastchannel/service-worker.https.html b/testing/web-platform/tests/webmessaging/broadcastchannel/service-worker.https.html
new file mode 100644
index 0000000000..d605434ae1
--- /dev/null
+++ b/testing/web-platform/tests/webmessaging/broadcastchannel/service-worker.https.html
@@ -0,0 +1,47 @@
+<!DOCTYPE html>
+<meta charset=utf-8>
+<script src="/resources/testharness.js"></script>
+<script src="/resources/testharnessreport.js"></script>
+<script>
+
+const SERVICE_WORKER_TEST_CHANNEL_NAME = 'service worker';
+const events = [];
+const c1 = new BroadcastChannel(SERVICE_WORKER_TEST_CHANNEL_NAME);
+const c2 = new BroadcastChannel(SERVICE_WORKER_TEST_CHANNEL_NAME);
+c1.onmessage = e => events.push(e);
+c2.onmessage = e => events.push(e);
+
+function testCompletion(t) {
+  return new Promise((resolve) => {
+    c2.addEventListener("message", t.step_func(e => {
+      if (e.data == 'from worker') {
+        c2.postMessage('from c2');
+      } else if (e.data == 'done') {
+        assert_equals(events.length, 5);
+        assert_equals(events[0].data, 'from worker');
+        assert_equals(events[0].target, c1);
+        assert_equals(events[1].data, 'from worker');
+        assert_equals(events[1].target, c2);
+        assert_equals(events[2].data, 'from c2');
+        assert_equals(events[3].data, 'done');
+        assert_equals(events[3].target, c1);
+        assert_equals(events[4].data, 'done');
+        assert_equals(events[4].target, c2);
+        resolve();
+      }
+    }));
+  });
+}
+
+promise_test(async t => {
+
+    const testResults = testCompletion(t);
+    const SCRIPT = "resources/service-worker.js";
+    const SCOPE = "/webmessaging/broadcastchannel/resources/not-used/";
+
+    const reg = await navigator.serviceWorker.register(SCRIPT, {'scope': SCOPE});
+    t.add_cleanup(() => reg.unregister());
+
+    return testResults;
+  }, 'BroadcastChannel works in service workers');
+</script>
diff --git a/testing/web-platform/tests/webmessaging/broadcastchannel/workers.html b/testing/web-platform/tests/webmessaging/broadcastchannel/workers.html
new file mode 100644
index 0000000000..8b55492f3c
--- /dev/null
+++ b/testing/web-platform/tests/webmessaging/broadcastchannel/workers.html
@@ -0,0 +1,375 @@
+<!DOCTYPE html>
+<meta charset=utf-8>
+<script src="/resources/testharness.js"></script>
+<script src="/resources/testharnessreport.js"></script>
+<script>
+
+async_test(t => {
+    let c1 = new BroadcastChannel('worker');
+    let c2 = new BroadcastChannel('worker');
+    let events = [];
+
+    c1.onmessage = e => events.push(e);
+    c2.onmessage = e => events.push(e);
+
+    let doneCount = 0;
+    c2.addEventListener('message', t.step_func(e => {
+        if (e.data == 'from worker') {
+          c2.postMessage('from c2');
+          c1.postMessage('done');
+        } else if (e.data == 'done') {
+          assert_equals(events.length, 4);
+          assert_equals(events[0].data, 'from worker');
+          assert_equals(events[0].target, c1);
+          assert_equals(events[1].data, 'from worker');
+          assert_equals(events[1].target, c2);
+          assert_equals(events[2].data, 'from c2');
+          assert_equals(events[3].data, 'done');
+          if (++doneCount == 2) t.done();
+        }
+      }));
+
+    let worker = new Worker('resources/worker.js');
+    worker.onmessage = t.step_func(e => {
+        assert_array_equals(e.data, ['from c2', 'done']);
+        if (++doneCount == 2) t.done();
+      });
+    worker.postMessage({channel: 'worker'});
+
+  }, 'BroadcastChannel works in workers');
+
+async_test(t => {
+    let c1 = new BroadcastChannel('shared worker');
+    let c2 = new BroadcastChannel('shared worker');
+    let events = [];
+
+    c1.onmessage = e => events.push(e);
+    c2.onmessage = e => events.push(e);
+
+    let doneCount = 0;
+    c2.addEventListener('message', t.step_func(e => {
+        if (e.data == 'from worker') {
+          c2.postMessage('from c2');
+          c1.postMessage('done');
+        } else if (e.data == 'done') {
+          assert_equals(events.length, 4);
+          assert_equals(events[0].data, 'from worker');
+          assert_equals(events[0].target, c1);
+          assert_equals(events[1].data, 'from worker');
+          assert_equals(events[1].target, c2);
+          assert_equals(events[2].data, 'from c2');
+          assert_equals(events[3].data, 'done');
+          if (++doneCount == 2) t.done();
+        }
+      }));
+
+    let worker = new SharedWorker('resources/worker.js');
+    worker.port.onmessage = t.step_func(e => {
+        assert_array_equals(e.data, ['from c2', 'done']);
+        if (++doneCount == 2) t.done();
+      });
+    worker.port.postMessage({channel: 'shared worker'});
+
+  }, 'BroadcastChannel works in shared workers');
+
+async_test(t => {
+    let c = new BroadcastChannel('worker-close');
+    let events = [];
+
+    c.onmessage = e => events.push('c1: ' + e.data);
+
+    let worker = new Worker('resources/worker.js');
+    worker.onmessage = t.step_func(e => {
+        assert_array_equals(events,
+                            ['c1: from worker', 'c2: ready', 'c2: echo'],
+                            'messages in document');
+        assert_array_equals(e.data, ['done'], 'messages in worker');
+        t.done();
+      });
+    worker.onmessagerror =
+        t.unreached_func('Worker\'s onmessageerror handler called');
+
+    c.addEventListener('message', e => {
+        if (e.data == 'from worker') {
+          c.close();
+          if (self.gc) self.gc();
+          window.setTimeout(() => {
+              let c2 = new BroadcastChannel('worker-close');
+              c2.onmessage = e => {
+                  events.push('c2: ' + e.data);
+                  if (e.data === 'ready') {
+                    worker.postMessage({ping: 'echo'});
+                  } else {
+                    c2.postMessage('done');
+                    c2.close();
+                  }
+                };
+              // For some implementations there may be a race condition between
+              // when the BroadcastChannel instance above is created / ready to
+              // receive messages and when the worker calls postMessage on it's
+              // BroadcastChannel instance. To avoid this, confirm that our
+              // instance can receive a message before indicating to the other
+              // thread that we are ready. For more details, see:
+              // https://github.com/whatwg/html/issues/7267
+              let c3 = new BroadcastChannel('worker-close');
+              c3.postMessage('ready');
+              c3.close();
+            }, 1);
+        }
+      });
+
+    worker.postMessage({channel: 'worker-close'});
+    t.add_cleanup(() => worker.terminate());
+
+  }, 'Closing and re-opening a channel works.');
+
+async_test(t => {
+  function workerCode() {
+    close();
+    try {
+      var bc = new BroadcastChannel('worker-create-after-close');
+    } catch (e) {
+      postMessage(e);
+      return;
+    }
+    postMessage(true);
+  }
+
+  var workerBlob = new Blob(
+      [workerCode.toString() + ';workerCode();'],
+      {type: 'application/javascript'});
+
+  var w = new Worker(URL.createObjectURL(workerBlob));
+  w.onmessage = t.step_func_done(function(e) {
+    assert_equals(
+        e.data, true,
+        'BroadcastChannel creation in closed worker triggered exception: ' +
+            e.data.message);
+  });
+  t.add_cleanup(() => w.terminate());
+}, 'BroadcastChannel created after a worker self.close()');
+
+
+function postMessageFromWorkerWorkerCode(workerName, channelName) {
+  if (workerName === 'close-before-create-worker') {
+    close();
+  }
+  let bc = new BroadcastChannel(channelName);
+  if (workerName === 'close-after-create-worker') {
+    close();
+  }
+  bc.postMessage(workerName + ' done');
+  postMessage(true);
+}
+
+function doPostMessageFromWorkerTest(t, workerName, channelName) {
+  var bc = new BroadcastChannel(channelName);
+  bc.onmessage = t.step_func_done(function(e) {
+    assert_equals(
+        e.data, 'done-worker done',
+        'BroadcastChannel message should only be received from the second worker');
+  });
+  t.add_cleanup(() => bc.close());
+
+  var testMessageHandler = t.step_func(function(e) {
+    assert_equals(
+        e.data, true,
+        'Worker sent postMessage indicating it sent a BroadcastChannel message');
+
+    var w = createWorker(
+        postMessageFromWorkerWorkerCode, 'done-worker', channelName);
+    t.add_cleanup(() => w.terminate());
+  });
+  createWorker(
+      postMessageFromWorkerWorkerCode, workerName, channelName,
+      testMessageHandler);
+
+  // To avoid calling t.step_timeout here, have the worker postMessage(true)
+  // once it is finished and then we'll instantiate another worker that
+  // performs the same test steps but doesn't close. By the time the
+  // BroadcastChannel message in that worker gets sent successfully it should
+  // be safe to assume that any BroadcastChannel messages from the previous
+  // worker would have been sent if they were going to be.
+}
+
+function createWorker(workerCode, workerName, channelName, handler = null) {
+  var workerCodeStr = workerCode.toString() +
+      `;${workerCode.name}("${workerName}", "${channelName}");`;
+  var workerBlob = new Blob([workerCodeStr], {type: 'application/javascript'});
+  var w = new Worker(URL.createObjectURL(workerBlob));
+  if (handler !== null) {
+    w.onmessage = handler;
+  }
+  return w;
+}
+
+async_test(t => {
+  const workerName = 'close-after-create-worker';
+  const channelName = workerName + '-postmessage-from-worker';
+  doPostMessageFromWorkerTest(t, workerName, channelName);
+}, 'BroadcastChannel messages from closed worker to parent should be ignored (BC created before closing)');
+
+async_test(t => {
+  const workerName = 'close-before-create-worker';
+  const channelName = workerName + '-postmessage-from-worker';
+  doPostMessageFromWorkerTest(t, workerName, channelName);
+}, 'BroadcastChannel messages from closed worker to parent should be ignored (BC created after closing)');
+
+
+function postMessageToWorkerWorkerCode(workerName, channelName) {
+  self.addEventListener('message', () => {
+    if (workerName === 'close-before-create-worker') {
+      close();
+    }
+    try {
+      let bc1 = new BroadcastChannel(channelName);
+      bc1.onmessage = e => {
+        if (e.data === 'ready') {
+          postMessage(e.data);
+        } else if (e.data === 'test') {
+          postMessage(workerName + ' done');
+        }
+      };
+      bc1.onmessageerror = () => {
+        postMessage('onmessageerror called from worker BroadcastChannel');
+      };
+      if (workerName === 'close-after-create-worker') {
+        close();
+      }
+    } catch (e) {
+      postMessage(e);
+      return;
+    }
+
+    if (workerName === 'done-worker') {
+      // For some implementations there may be a race condition between when
+      // the BroadcastChannel instance above is created / ready to receive
+      // messages and when the parent calls postMessage on it's
+      // BroadcastChannel instance. To avoid this, confirm that our instance
+      // can receive a message before indicating to the other thread that we
+      // are ready. For more details, see:
+      // https://github.com/whatwg/html/issues/7267
+      let bc2 = new BroadcastChannel(channelName);
+      bc2.postMessage('ready');
+      bc2.close();
+    } else {
+      // Since the worker has closed, it's not expected that the
+      // BroadcastChannel will receive messages (there's a separate test for
+      // that), so just indicate directly that it's ready to test receiving
+      // a message from the parent dispite the possibility of a race condition.
+      postMessage('ready');
+    }
+  });
+  self.addEventListener('messageerror', () => {
+    postMessage('onmessageerror called from worker');
+  });
+}
+
+function doPostMessageToWorkerTest(t, workerName, channelName) {
+  var bc = new BroadcastChannel(channelName);
+  t.add_cleanup(() => bc.close());
+
+  var doneMessageHandler = t.step_func(function(e) {
+    if (e.data === 'ready') {
+      bc.postMessage('test');
+    } else if (e.data === 'done-worker done') {
+      t.done();
+    } else {
+      assert_unreached(
+          'BroadcastChannel.postMessage triggered exception within second worker: ' +
+          e.data.message);
+    }
+  });
+  var testMessageHandler = t.step_func(function(e) {
+    assert_equals(
+        e.data, 'ready',
+        'Worker sent postMessage indicating its BroadcastChannel instance is ready');
+    bc.postMessage('test');
+
+    var doneWorker = createWorker(
+        postMessageToWorkerWorkerCode, 'done-worker', channelName,
+        doneMessageHandler);
+    t.add_cleanup(() => {
+      doneWorker.terminate();
+    });
+    doneWorker.postMessage('start');
+  });
+  var testWorker = createWorker(
+      postMessageToWorkerWorkerCode, workerName, channelName,
+      testMessageHandler);
+  testWorker.postMessage('start');
+}
+
+async_test(t => {
+  const workerName = 'close-after-create-worker';
+  const channelName = workerName + '-postmessage-to-worker';
+  doPostMessageToWorkerTest(t, workerName, channelName);
+}, 'BroadcastChannel messages from parent to closed worker should be ignored (BC created before closing)');
+
+async_test(t => {
+  const workerName = 'close-before-create-worker';
+  const channelName = workerName + '-postmessage-to-worker';
+  doPostMessageToWorkerTest(t, workerName, channelName);
+}, 'BroadcastChannel messages from parent to closed worker should be ignored (BC created after closing)');
+
+
+function postMessageWithinWorkerWorkerCode(workerName, channelName) {
+  if (workerName === 'close-before-create-worker') {
+    close();
+  }
+  try {
+    let bc1 = new BroadcastChannel(channelName);
+    let bc2 = new BroadcastChannel(channelName);
+    bc1.onmessage = e => {
+      postMessage(workerName + ' done')
+    };
+    if (workerName === 'close-after-create-worker') {
+      close();
+    }
+    bc2.postMessage(true);
+    postMessage(true);
+  } catch (e) {
+    postMessage(e);
+  }
+}
+
+function doPostMessageWithinWorkerTest(t, workerName, channelName) {
+  var doneMessageHandler = t.step_func(function(e) {
+    if (e.data === true) {
+      // Done worker has finished - no action needed
+    } else if (e.data === 'done-worker done') {
+      t.done();
+    } else {
+      assert_unreached(
+          'BroadcastChannel.postMessage triggered exception within second worker: ' +
+          e.data.message);
+    }
+  });
+  var testMessageHandler = t.step_func(function(e) {
+    assert_equals(
+        e.data, true,
+        'Worker indicated that the test procedures were executed successfully');
+
+    var w = createWorker(
+        postMessageWithinWorkerWorkerCode, 'done-worker', channelName,
+        doneMessageHandler);
+    t.add_cleanup(() => w.terminate());
+  });
+  createWorker(
+      postMessageWithinWorkerWorkerCode, workerName, channelName,
+      testMessageHandler);
+}
+
+async_test(t => {
+  const workerName = 'close-after-create-worker';
+  const channelName = workerName + '-postmessage-within-worker';
+  doPostMessageWithinWorkerTest(t, workerName, channelName);
+}, 'BroadcastChannel messages within closed worker should be ignored (BCs created before closing)');
+
+async_test(t => {
+  const workerName = 'close-before-create-worker';
+  const channelName = workerName + '-postmessage-within-worker';
+  doPostMessageWithinWorkerTest(t, workerName, channelName);
+}, 'BroadcastChannel messages within closed worker should be ignored (BCs created after closing)');
+
+</script>
diff --git a/testing/web-platform/tests/webmessaging/event.data.sub.htm b/testing/web-platform/tests/webmessaging/event.data.sub.htm
new file mode 100644
index 0000000000..6858ef4c69
--- /dev/null
+++ b/testing/web-platform/tests/webmessaging/event.data.sub.htm
@@ -0,0 +1,44 @@
+<!DOCTYPE html>
+<html>
+<head>
+<title> event.data returns the data of the message </title>
+<script src="/resources/testharness.js"></script>
+<script src="/resources/testharnessreport.js"></script>
+</head>
+<body>
+<div id=log></div>
+
+<script>
+
+
+    var description = "Test Description: event.data returns the data of the message.";
+
+    var t = async_test(description);
+
+    var PORT = location.port !== "" ? ":" + location.port : "";
+    var DATA = "STRING";
+    var TYPE = "string";
+    var XORIGIN = "{{location[scheme]}}://{{domains[www]}}" + PORT;
+    var SORIGIN = "{{location[scheme]}}://{{host}}" + PORT;
+    var ExpectedResult = [DATA, TYPE, DATA, TYPE];
+    var ActualResult = [];
+
+    window.onmessage = t.step_func(function(e)
+    {
+        if (e.data.toString() === "STRING") {
+           ActualResult.push(e.data, typeof(e.data));
+
+           if (ActualResult.length >= ExpectedResult.length) {
+               assert_array_equals(ActualResult, ExpectedResult, "ActualResult");
+                t.done();
+           }
+        }
+    });
+</script>
+
+<div style="display:none">
+    <iframe width="70%" onload="this.contentWindow.postMessage(DATA, XORIGIN)" src="{{location[scheme]}}://{{domains[www]}}:{{location[port]}}/webmessaging/support/ChildWindowPostMessage.htm"></iframe>
+    <iframe width="70%" onload="this.contentWindow.postMessage(DATA, SORIGIN)" src="./support/ChildWindowPostMessage.htm"></iframe>
+</div>
+</body>
+</html>
diff --git a/testing/web-platform/tests/webmessaging/event.origin.sub.htm b/testing/web-platform/tests/webmessaging/event.origin.sub.htm
new file mode 100644
index 0000000000..5b1ab3e3c3
--- /dev/null
+++ b/testing/web-platform/tests/webmessaging/event.origin.sub.htm
@@ -0,0 +1,66 @@
+<!DOCTYPE html>
+<html>
+<head>
+<title> event.origin returns the origin of the message </title>
+<script src="/resources/testharness.js"></script>
+<script src="/resources/testharnessreport.js"></script>
+</head>
+<body>
+<div id=log></div>
+
+<div style="display:none">
+    <iframe width="70%" onload="PostMessageTest()" src="{{location[scheme]}}://{{domains[天気の良い日]}}:{{location[port]}}/webmessaging/support/ChildWindowPostMessage.htm"></iframe>
+    <iframe width="70%" onload="PostMessageTest()" src="./support/ChildWindowPostMessage.htm"></iframe>
+</div>
+
+<script>
+
+
+    var description = "Test Description: event.origin returns the origin of the message.";
+
+    var t = async_test(description);
+
+    var PORT = location.port !== "" ? ":" + location.port : "";
+    var TARGET1 = document.querySelectorAll("iframe")[0];
+    var TARGET2 = document.querySelectorAll("iframe")[1];
+    var XORIGIN = "{{location[scheme]}}://{{domains[天気の良い日]}}" + PORT;
+    var SORIGIN = "{{location[scheme]}}://{{host}}" + PORT;
+    var ExpectedResult = ["#1", XORIGIN, "#2", SORIGIN];
+    var ActualResult = [];
+    var loaded = 0;
+
+    function PostMessageTest()
+    {
+        loaded++;
+
+        if (loaded == 2)
+        {
+            TARGET1.contentWindow.postMessage("#1", XORIGIN);
+            TARGET2.contentWindow.postMessage("#2", SORIGIN);
+        }
+    }
+
+    window.onmessage = t.step_func(function(e)
+    {
+        // Messages from TARGET1 and TARGET2 can come in any order
+        // (since one of them is cross-origin and can run in parallel).
+        // To make the tests immune to message reordering, always
+        // put the response from TARGET1 at the start of the list.
+        if (e.data.toString() === "#1")
+        {
+            ActualResult = [e.data, e.origin].concat(ActualResult);
+        }
+        else if (e.data.toString() === "#2")
+        {
+            ActualResult = ActualResult.concat([e.data, e.origin]);
+        }
+
+        if (ActualResult.length >= ExpectedResult.length)
+        {
+            assert_array_equals(ActualResult, ExpectedResult, "ActualResult");
+            t.done();
+        }
+    });
+</script>
+</body>
+</html>
diff --git a/testing/web-platform/tests/webmessaging/event.ports.sub.htm b/testing/web-platform/tests/webmessaging/event.ports.sub.htm
new file mode 100644
index 0000000000..a4ca24b15e
--- /dev/null
+++ b/testing/web-platform/tests/webmessaging/event.ports.sub.htm
@@ -0,0 +1,49 @@
+<!DOCTYPE html>
+<html>
+<head>
+<title> event.ports returns the MessagePort array sent with the message </title>
+<script src="/resources/testharness.js"></script>
+<script src="/resources/testharnessreport.js"></script>
+</head>
+<body>
+<div id=log></div>
+
+<div style="display:none">
+    <iframe width="70%" onload="PostMessageTest()" src="{{location[scheme]}}://{{domains[www1]}}:{{location[port]}}/webmessaging/support/ChildWindowPostMessage.htm"></iframe>
+</div>
+
+<script>
+
+
+    var description = "Test Description: event.ports returns the MessagePort array sent with the message.";
+
+    var t = async_test(description);
+
+    var DATA = {test: "e.source.postMessage(e.ports.toString(), '*', e.ports)"};
+    var TARGET = document.querySelector("iframe");
+    var ExpectedResult = "";
+
+    function PostMessageTest()
+    {
+        test(function()
+        {
+            assert_own_property(window, "MessageChannel", "window");
+
+            var channel = new MessageChannel();
+            var ports = [channel.port1, channel.port2];
+            ExpectedResult = ports.toString();
+            TARGET.contentWindow.postMessage(DATA, "*", ports);
+
+        }, "MessageChannel is supported.");
+    }
+
+    window.onmessage = t.step_func(function(e)
+    {
+        assert_equals(e.data, ExpectedResult, "e.data");
+        assert_true(e.ports[0] instanceof MessagePort, e.ports[0] + " instanceof MessageChannel");
+        assert_true(e.ports[1] instanceof MessagePort, e.ports[1] + " instanceof MessageChannel");
+        t.done();
+    });
+</script>
+</body>
+</html>
diff --git a/testing/web-platform/tests/webmessaging/event.source.htm b/testing/web-platform/tests/webmessaging/event.source.htm
new file mode 100644
index 0000000000..365a5feb47
--- /dev/null
+++ b/testing/web-platform/tests/webmessaging/event.source.htm
@@ -0,0 +1,51 @@
+<!DOCTYPE html>
+<html>
+<head>
+<title> Same-origin: event.source returns the WindowProxy of the source window </title>
+<script src="/resources/testharness.js"></script>
+<script src="/resources/testharnessreport.js"></script>
+</head>
+<body>
+<div id=log></div>
+
+<div style="display:none">
+    <iframe width="70%" onload="PostMessageTest()" src="./support/ChildWindowPostMessage.htm"></iframe>
+</div>
+
+<script>
+
+
+    var description = "Test Description: Same-origin: event.source returns the WindowProxy of the source window.";
+
+    var t = async_test(description);
+
+    var DATA = "foo";
+    var TARGET = document.querySelector("iframe");
+    var SORIGIN = location.protocol + "//" + location.host;
+    var ExpectedResult = [SORIGIN, "AccessCookieAllowed"];
+    var ActualResult = [];
+
+    function PostMessageTest()
+    {
+        TARGET.contentWindow.postMessage(DATA, SORIGIN);
+    }
+
+    window.onmessage = t.step_func(function(e)
+    {
+        try
+        {
+            var sdomainCookie = e.source.document.cookie;
+            ActualResult.push(e.origin, "AccessCookieAllowed");
+        }
+        catch(ex)
+        {
+            ActualResult.push(e.origin, "AccessCookieDenied");
+        }
+
+        assert_equals(e.source, TARGET.contentWindow);
+        assert_array_equals(ActualResult, ExpectedResult, "ActualResult");
+        t.done();
+    });
+</script>
+</body>
+</html>
diff --git a/testing/web-platform/tests/webmessaging/event.source.xorigin.sub.htm b/testing/web-platform/tests/webmessaging/event.source.xorigin.sub.htm
new file mode 100644
index 0000000000..7327f78667
--- /dev/null
+++ b/testing/web-platform/tests/webmessaging/event.source.xorigin.sub.htm
@@ -0,0 +1,51 @@
+<!DOCTYPE html>
+<html>
+<head>
+<title> Corss-origin: event.source returns the WindowProxy of the source window </title>
+<script src="/resources/testharness.js"></script>
+<script src="/resources/testharnessreport.js"></script>
+</head>
+<body>
+<div id=log></div>
+
+<div style="display:none">
+    <iframe width="70%" onload="PostMessageTest()" src="{{location[scheme]}}://{{domains[www1]}}:{{location[port]}}/webmessaging/support/ChildWindowPostMessage.htm"></iframe>
+</div>
+
+<script>
+
+    var description = "Test Description: Cross-origin: event.source returns the WindowProxy of the source window.";
+
+    var t = async_test(description);
+
+    var PORT = location.port !== "" ? ":" + location.port : "";
+    var DATA = "foo";
+    var TARGET = document.querySelector("iframe");
+    var XORIGIN = "{{location[scheme]}}://{{domains[www1]}}" + PORT;
+    var ExpectedResult = [XORIGIN, "AccessCookieDenied"];
+    var ActualResult = [];
+
+    function PostMessageTest()
+    {
+        TARGET.contentWindow.postMessage(DATA, XORIGIN);
+    }
+
+    window.onmessage = t.step_func(function(e)
+    {
+        try
+        {
+            var sdomainCookie = e.source.document.cookie;
+            ActualResult.push(e.origin, "AccessCookieAllowed");
+        }
+        catch(ex)
+        {
+            ActualResult.push(e.origin, "AccessCookieDenied");
+        }
+
+        assert_equals(e.source.parent, window);
+        assert_array_equals(ActualResult, ExpectedResult, "ActualResult");
+        t.done();
+    });
+</script>
+</body>
+</html>
diff --git a/testing/web-platform/tests/webmessaging/message-channels/basics.any.js b/testing/web-platform/tests/webmessaging/message-channels/basics.any.js
new file mode 100644
index 0000000000..5732fb268a
--- /dev/null
+++ b/testing/web-platform/tests/webmessaging/message-channels/basics.any.js
@@ -0,0 +1,12 @@
+// META: title=basic messagechannel test
+
+async_test(function(t) {
+  var channel = new MessageChannel();
+  channel.port1.postMessage(1);
+  channel.port2.onmessage = t.step_func(
+    function(e) {
+      assert_equals(e.data, 1);
+      t.done();
+    });
+  channel.port2.start();
+});
diff --git a/testing/web-platform/tests/webmessaging/message-channels/close.any.js b/testing/web-platform/tests/webmessaging/message-channels/close.any.js
new file mode 100644
index 0000000000..8741d894b9
--- /dev/null
+++ b/testing/web-platform/tests/webmessaging/message-channels/close.any.js
@@ -0,0 +1,62 @@
+// How long (in ms) these tests should wait before deciding no further messages
+// will be received.
+const time_to_wait_for_messages = 100;
+
+async_test(t => {
+    const c = new MessageChannel();
+    c.port1.onmessage = t.unreached_func('Should not have delivered message');
+    c.port1.close();
+    c.port2.postMessage('TEST');
+    setTimeout(t.step_func_done(), time_to_wait_for_messages);
+  }, 'Message sent to closed port should not arrive.');
+
+async_test(t => {
+    const c = new MessageChannel();
+    c.port1.onmessage = t.unreached_func('Should not have delivered message');
+    c.port2.close();
+    c.port2.postMessage('TEST');
+    setTimeout(t.step_func_done(), time_to_wait_for_messages);
+  }, 'Message sent from closed port should not arrive.');
+
+async_test(t => {
+    const c = new MessageChannel();
+    c.port1.onmessage = t.unreached_func('Should not have delivered message');
+    c.port1.close();
+    const c2 = new MessageChannel();
+    c2.port1.onmessage = t.step_func(e => {
+        e.ports[0].postMessage('TESTMSG');
+        setTimeout(t.step_func_done(), time_to_wait_for_messages);
+      });
+    c2.port2.postMessage('TEST', [c.port2]);
+  }, 'Message sent to closed port from transferred port should not arrive.');
+
+async_test(t => {
+    const c = new MessageChannel();
+    let isClosed = false;
+    c.port1.onmessage = t.step_func_done(e => {
+        assert_true(isClosed);
+        assert_equals(e.data, 'TEST');
+      });
+    c.port2.postMessage('TEST');
+    c.port2.close();
+    isClosed = true;
+  }, 'Inflight messages should be delivered even when sending port is closed afterwards.');
+
+async_test(t => {
+    const c = new MessageChannel();
+    c.port1.onmessage = t.step_func_done(e => {
+        if (e.data == 'DONE') t.done();
+        assert_equals(e.data, 'TEST');
+        c.port1.close();
+      });
+    c.port2.postMessage('TEST');
+    c.port2.postMessage('DONE');
+  }, 'Close in onmessage should not cancel inflight messages.');
+
+test(() => {
+  const c1 = new MessageChannel();
+  const c2 = new MessageChannel();
+  c1.port1.close();
+  assert_throws_dom("DataCloneError", () => c2.port1.postMessage(null, [c1.port1]));
+  c2.port1.postMessage(null, [c1.port2]);
+}, "close() detaches a MessagePort (but not the one its entangled with)");
diff --git a/testing/web-platform/tests/webmessaging/message-channels/cross-document.html b/testing/web-platform/tests/webmessaging/message-channels/cross-document.html
new file mode 100644
index 0000000000..f4512ba5a2
--- /dev/null
+++ b/testing/web-platform/tests/webmessaging/message-channels/cross-document.html
@@ -0,0 +1,22 @@
+<!doctype html>
+<title>cross-document channel</title>
+<script src="/resources/testharness.js"></script>
+<script src="/resources/testharnessreport.js"></script>
+<iframe src=resources/cross-document-1.html></iframe><iframe src=resources/cross-document-2.html></iframe>
+<div id="log"></div>
+<script>
+var t = async_test();
+onload = t.step_func(
+  function() {
+    var channel = new MessageChannel();
+    window[0].postMessage(1, '*', [channel.port1]);
+    window[1].postMessage(2, '*', [channel.port2]);
+    channel = null;
+    window.onmessage = t.step_func(
+      function(e) {
+        assert_equals(e.data, 1);
+        t.done();
+      });
+  }
+);
+</script>
diff --git a/testing/web-platform/tests/webmessaging/message-channels/detached-iframe.window.js b/testing/web-platform/tests/webmessaging/message-channels/detached-iframe.window.js
new file mode 100644
index 0000000000..c19f50ff93
--- /dev/null
+++ b/testing/web-platform/tests/webmessaging/message-channels/detached-iframe.window.js
@@ -0,0 +1,46 @@
+// META: title=MessageChannel in a detached iframe test
+// META: script=/service-workers/service-worker/resources/test-helpers.sub.js
+// META: script=/common/gc.js
+// Pull in the with_iframe helper function from the service worker tests
+
+
+const IframeAction = {
+  REMOVE_BEFORE_CREATION: 'remove-before-creation',
+  REMOVE_AFTER_CREATION: 'remove-after-creation',
+};
+
+async function detached_frame_test(t, action) {
+  const iframe = await with_iframe('about:blank');
+  const iframe_MessageChannel = iframe.contentWindow.MessageChannel;
+
+  if (action === IframeAction.REMOVE_BEFORE_CREATION) {
+    iframe.remove();
+  }
+
+  (() => {
+    const mc = new iframe_MessageChannel();
+    mc.port1.postMessage("boo");
+    mc.port2.onmessage = t.unreached_func("message event received");
+    mc.port2.onmessageerror = t.unreached_func("message event received");
+  })();
+
+  if (action === IframeAction.REMOVE_AFTER_CREATION) {
+    iframe.remove();
+  }
+
+  await garbageCollect();
+
+  // We are testing that neither of the above two events fire. We assume that a 2 second timeout
+  // is good enough. We can't use any other API for an end condition because each MessagePort has
+  // its own independent port message queue, which has no ordering guarantees relative to other
+  // APIs.
+  await new Promise(resolve => t.step_timeout(resolve, 2000));
+}
+
+promise_test(async (t) => {
+  return detached_frame_test(t, IframeAction.REMOVE_AFTER_CREATION);
+}, 'MessageChannel created from a detached iframe should not send messages (remove after create)');
+
+promise_test(async (t) => {
+  return detached_frame_test(t, IframeAction.REMOVE_BEFORE_CREATION);
+}, 'MessageChannel created from a detached iframe should not send messages (remove before create)');
diff --git a/testing/web-platform/tests/webmessaging/message-channels/dictionary-transferrable.any.js b/testing/web-platform/tests/webmessaging/message-channels/dictionary-transferrable.any.js
new file mode 100644
index 0000000000..bf49fddb99
--- /dev/null
+++ b/testing/web-platform/tests/webmessaging/message-channels/dictionary-transferrable.any.js
@@ -0,0 +1,13 @@
+// META: title=basic messagechannel with transfer
+
+async_test(function(t) {
+  var channel = new MessageChannel();
+  var ab = new ArrayBuffer(1);
+  channel.port1.postMessage(ab, {transfer: [ab]});
+  channel.port2.onmessage = t.step_func(
+    function(e) {
+      assert_equals(e.data.byteLength, 1);
+      t.done();
+    });
+  channel.port2.start();
+});
diff --git a/testing/web-platform/tests/webmessaging/message-channels/implied-start.any.js b/testing/web-platform/tests/webmessaging/message-channels/implied-start.any.js
new file mode 100644
index 0000000000..460d26b7e4
--- /dev/null
+++ b/testing/web-platform/tests/webmessaging/message-channels/implied-start.any.js
@@ -0,0 +1,14 @@
+// META: title=onmessage implied start()
+
+async_test(function(t) {
+  var channel = new MessageChannel();
+  channel.port1.postMessage(1);
+  channel.port2.onmessage = function() {
+    setTimeout(t.step_func(function() {
+      t.done();
+    }), 50);
+    channel.port2.onmessage = t.step_func(function() {
+      assert_unreached();
+    });
+  }; // implies start()
+});
diff --git a/testing/web-platform/tests/webmessaging/message-channels/no-start.any.js b/testing/web-platform/tests/webmessaging/message-channels/no-start.any.js
new file mode 100644
index 0000000000..75b1ea1b26
--- /dev/null
+++ b/testing/web-platform/tests/webmessaging/message-channels/no-start.any.js
@@ -0,0 +1,9 @@
+// META: title=without start()
+
+async_test(function(t) {
+  var channel = new MessageChannel();
+  channel.port1.postMessage(1);
+  var i = 0;
+  channel.port2.addEventListener('message', function() { i++; }, false);
+  setTimeout(t.step_func(function() { assert_equals(i, 0); t.done();}), 50);
+});
diff --git a/testing/web-platform/tests/webmessaging/message-channels/resources/cross-document-1.html b/testing/web-platform/tests/webmessaging/message-channels/resources/cross-document-1.html
new file mode 100644
index 0000000000..93725a93f8
--- /dev/null
+++ b/testing/web-platform/tests/webmessaging/message-channels/resources/cross-document-1.html
@@ -0,0 +1,8 @@
+<!doctype html>
+<title>crosss-document-1</title>
+<script>
+onmessage = function(e) {
+  var port = e.ports[0];
+  port.postMessage(e.data);
+}
+</script>
\ No newline at end of file
diff --git a/testing/web-platform/tests/webmessaging/message-channels/resources/cross-document-2.html b/testing/web-platform/tests/webmessaging/message-channels/resources/cross-document-2.html
new file mode 100644
index 0000000000..1b8ef0a7a0
--- /dev/null
+++ b/testing/web-platform/tests/webmessaging/message-channels/resources/cross-document-2.html
@@ -0,0 +1,10 @@
+<!doctype html>
+<title>004-2</title>
+<script>
+onmessage = function(e) {
+  var port = e.ports[0];
+  port.onmessage = function(e) { // implied start()
+    parent.postMessage(e.data, '*');
+  }
+}
+</script>
\ No newline at end of file
diff --git a/testing/web-platform/tests/webmessaging/message-channels/user-activation.tentative.any.js b/testing/web-platform/tests/webmessaging/message-channels/user-activation.tentative.any.js
new file mode 100644
index 0000000000..175662873c
--- /dev/null
+++ b/testing/web-platform/tests/webmessaging/message-channels/user-activation.tentative.any.js
@@ -0,0 +1,21 @@
+// META: title=user activation messagechannel test
+
+async_test(function(t) {
+  var channel = new MessageChannel();
+  channel.port1.postMessage(1, {includeUserActivation: true});
+  channel.port1.postMessage(2);
+  var expected_data = 1;
+  channel.port2.onmessage = t.step_func(
+    function(e) {
+      assert_equals(e.data, expected_data);
+      expected_data++;
+      if (e.data == 1) {
+        assert_false(e.userActivation.isActive);
+        assert_false(e.userActivation.hasBeenActive);
+      } else {
+        assert_equals(e.userActivation, null);
+        t.done();
+      }
+    });
+  channel.port2.start();
+});
diff --git a/testing/web-platform/tests/webmessaging/message-channels/worker-post-after-close.any.js b/testing/web-platform/tests/webmessaging/message-channels/worker-post-after-close.any.js
new file mode 100644
index 0000000000..2de0c434de
--- /dev/null
+++ b/testing/web-platform/tests/webmessaging/message-channels/worker-post-after-close.any.js
@@ -0,0 +1,28 @@
+async_test(t => {
+  function workerCode() {
+    onmessage = function(e) {
+      close();
+      var mc = new MessageChannel();
+      mc.port1.onmessage = function() {
+        postMessage("message received!");
+      }
+      mc.port2.postMessage(42);
+      postMessage("done");
+    }
+  }
+
+  var workerBlob = new Blob([workerCode.toString() + ";workerCode();"], {type:"application/javascript"});
+
+  var w = new Worker(URL.createObjectURL(workerBlob));
+  w.postMessage('');
+  w.onmessage = function(e) {
+    if (e.data == "done") {
+      setTimeout(function() {
+        t.done();
+      }, 250);
+    } else {
+      assert_true(false, "A wrong message has been received!");
+    }
+  }
+}, 'MessageChannel/MessagePort should not work after a worker self.close()');
+
diff --git a/testing/web-platform/tests/webmessaging/message-channels/worker.any.js b/testing/web-platform/tests/webmessaging/message-channels/worker.any.js
new file mode 100644
index 0000000000..633d89a371
--- /dev/null
+++ b/testing/web-platform/tests/webmessaging/message-channels/worker.any.js
@@ -0,0 +1,17 @@
+async_test(t => {
+  function workerCode() {
+    close();
+    var mc = new MessageChannel();
+    mc.port1.postMessage(42);
+    mc.port2.postMessage(42);
+    postMessage(true);
+  }
+
+  var workerBlob = new Blob([workerCode.toString() + ";workerCode();"], {type:"application/javascript"});
+
+  var w = new Worker(URL.createObjectURL(workerBlob));
+  w.onmessage = function(e) {
+    assert_true(e.data, "MessageChannel created on worker shutdown.");
+    t.done();
+  }
+}, 'MessageChannel/MessagePort created and used after a worker self.close()');
diff --git a/testing/web-platform/tests/webmessaging/messageerror.html b/testing/web-platform/tests/webmessaging/messageerror.html
new file mode 100644
index 0000000000..2cb51ee3c0
--- /dev/null
+++ b/testing/web-platform/tests/webmessaging/messageerror.html
@@ -0,0 +1,44 @@
+<!DOCTYPE html>
+<title>onmessageerror content attribute</title>
+<link rel="author" title="Domenic Denicola" href="mailto:d@domenic.me">
+<link rel="help" href="https://html.spec.whatwg.org/multipage/#handler-onmessageerror">
+<script src="/resources/testharness.js"></script>
+<script src="/resources/testharnessreport.js"></script>
+
+<body>
+
+<script>
+"use strict";
+window.messageErrorHappened = false;
+
+function cleanup() {
+  window.messageErrorHappened = false;
+  document.body.removeAttribute("onmessageerror");
+}
+
+test(() => {
+  assert_equals(document.body.onmessageerror, null, "body");
+  assert_equals(window.onmessageerror, null, "window");
+}, "The default value of onmessageerror is null");
+
+test(t => {
+  t.add_cleanup(cleanup);
+
+  document.body.setAttribute("onmessageerror", "window.messageErrorHappened = true;")
+  const compiledHandler = document.body.onmessageerror;
+
+  assert_equals(typeof compiledHandler, "function", "The onmessageerror property must be a function");
+  compiledHandler();
+  assert_true(window.messageErrorHappened, "Calling the handler must run the code");
+}, "The onmessageerror content attribute must be compiled into the onmessageerror property");
+
+test(t => {
+  t.add_cleanup(cleanup);
+
+  document.body.setAttribute("onmessageerror", "window.messageErrorHappened = true;")
+
+  window.dispatchEvent(new Event("messageerror"));
+
+  assert_true(window.messageErrorHappened, "Dispatching the event must run the code");
+}, "The onmessageerror content attribute must execute when an event is dispatched on the window");
+</script>
diff --git a/testing/web-platform/tests/webmessaging/multi-globals/broadcastchannel-current.sub.html b/testing/web-platform/tests/webmessaging/multi-globals/broadcastchannel-current.sub.html
new file mode 100644
index 0000000000..ae2369394e
--- /dev/null
+++ b/testing/web-platform/tests/webmessaging/multi-globals/broadcastchannel-current.sub.html
@@ -0,0 +1,45 @@
+<!DOCTYPE html>
+<meta charset="utf-8">
+<title>The current page being cross-origin must prevent the BroadcastChannel message from being seen</title>
+<script src="/resources/testharness.js"></script>
+<script src="/resources/testharnessreport.js"></script>
+
+<!-- This is the entry global -->
+
+<iframe src="support/incumbent-document-domain.sub.html" id="incumbent"></iframe>
+<iframe src="http://{{hosts[][www]}}:{{ports[http][0]}}/webmessaging/multi-globals/support/current-document-domain.sub.html" id="current"></iframe>
+
+<script>
+"use strict";
+document.domain = "{{hosts[][]}}";
+
+setup({ explicit_done: true });
+
+const incumbentIframe = document.querySelector("#incumbent");
+const currentIframe = document.querySelector("#current");
+
+window.onload = () => {
+  promise_test(async t => {
+    const createdCrossOrigin = frames[0].createBroadcastChannel("current");
+    const createdSameOrigin = new BroadcastChannel("current");
+
+    createdSameOrigin.onmessage = t.unreached_func("message event fired");
+    createdSameOrigin.onmessageerror = t.unreached_func("messageerror event fired");
+
+    createdCrossOrigin.postMessage("the message");
+
+    // BroadcastChannel messages are guaranteed to be ordered within an event loop, as they all use
+    // the DOM manipulation task source. So, any messages from the "current" channel, if they are
+    // going to be erroneously delivered, would have to be delivered before those from this
+    // channel. I.e., if we recieve a message from this channel without first recieving one from
+    // the "current" channel, then the test passes.
+    const testEnder = new BroadcastChannel("current / test-ender");
+    const testEnder2 = new BroadcastChannel("current / test-ender");
+
+    testEnder.postMessage("end test");
+    await new Promise(resolve => testEnder2.onmessage = resolve);
+  });
+
+  done();
+};
+</script>
diff --git a/testing/web-platform/tests/webmessaging/multi-globals/broadcastchannel-incumbent.sub.html b/testing/web-platform/tests/webmessaging/multi-globals/broadcastchannel-incumbent.sub.html
new file mode 100644
index 0000000000..31a4221c1d
--- /dev/null
+++ b/testing/web-platform/tests/webmessaging/multi-globals/broadcastchannel-incumbent.sub.html
@@ -0,0 +1,34 @@
+<!DOCTYPE html>
+<meta charset="utf-8">
+<title>The incumbent page being cross-origin must not prevent the BroadcastChannel message from being seen</title>
+<script src="/resources/testharness.js"></script>
+<script src="/resources/testharnessreport.js"></script>
+
+<!-- This is the entry global -->
+
+<iframe src="http://{{hosts[][www]}}:{{ports[http][0]}}/webmessaging/multi-globals/support/incumbent-document-domain.sub.html" id="incumbent"></iframe>
+<iframe src="support/current-document-domain.sub.html" id="current"></iframe>
+
+<script>
+"use strict";
+document.domain = "{{hosts[][]}}";
+
+setup({ explicit_done: true });
+
+const incumbentIframe = document.querySelector("#incumbent");
+const currentIframe = document.querySelector("#current");
+
+window.onload = () => {
+  async_test(t => {
+    const createdThroughCrossOrigin = frames[0].createBroadcastChannel("incumbent");
+    const createdSameOrigin = new BroadcastChannel("incumbent");
+
+    createdSameOrigin.onmessage = () => t.done();
+    createdSameOrigin.onmessageerror = t.unreached_func("messageerror event fired");
+
+    createdThroughCrossOrigin.postMessage("the message");
+  });
+
+  done();
+};
+</script>
diff --git a/testing/web-platform/tests/webmessaging/multi-globals/messageport-current.html b/testing/web-platform/tests/webmessaging/multi-globals/messageport-current.html
new file mode 100644
index 0000000000..ee172c6138
--- /dev/null
+++ b/testing/web-platform/tests/webmessaging/multi-globals/messageport-current.html
@@ -0,0 +1,39 @@
+<!DOCTYPE html>
+<meta charset="utf-8">
+<title>Making the current page become non-active must prevent message transmission</title>
+<script src="/resources/testharness.js"></script>
+<script src="/resources/testharnessreport.js"></script>
+
+<!-- This is the entry global -->
+
+<iframe src="support/incumbent.html" id="incumbent"></iframe>
+<iframe src="support/current.html" id="current"></iframe>
+
+<script>
+"use strict";
+const incumbentIframe = document.querySelector("#incumbent");
+const currentIframe = document.querySelector("#current");
+
+window.addEventListener("load", () => {
+  promise_test(async t => {
+    // This will invoke the constructor from currentIframe, but with incumbentIframe as the incumbent.
+    const messageChannel = incumbentIframe.contentWindow.createMessageChannel();
+
+    await new Promise((resolve, reject) => {
+      currentIframe.onload = () => resolve();
+      currentIframe.onerror = () => reject(new Error("Could not navigate the iframe"));
+      currentIframe.src = "/common/blank.html";
+    });
+
+    messageChannel.port1.onmessage = t.unreached_func("message event recieved");
+    messageChannel.port1.onmessageerror = t.unreached_func("messageerror event recieved");
+    messageChannel.port2.postMessage("boo");
+
+    // We are testing that neither of the above two events fire. We assume that a 3 second timeout
+    // is good enough. We can't use any other API for an end condition because each MessagePort has
+    // its own independent port message queue, which has no ordering guarantees relative to other
+    // APIs.
+    await new Promise(resolve => t.step_timeout(resolve, 3000));
+  });
+});
+</script>
diff --git a/testing/web-platform/tests/webmessaging/multi-globals/messageport-incumbent.html b/testing/web-platform/tests/webmessaging/multi-globals/messageport-incumbent.html
new file mode 100644
index 0000000000..4d47fb8124
--- /dev/null
+++ b/testing/web-platform/tests/webmessaging/multi-globals/messageport-incumbent.html
@@ -0,0 +1,35 @@
+<!DOCTYPE html>
+<meta charset="utf-8">
+<title>Making the incumbent page become non-active must not prevent message transmission</title>
+<script src="/resources/testharness.js"></script>
+<script src="/resources/testharnessreport.js"></script>
+
+<!-- This is the entry global -->
+
+<iframe src="support/incumbent.html" id="incumbent"></iframe>
+<iframe src="support/current.html" id="current"></iframe>
+
+<script>
+"use strict";
+const incumbentIframe = document.querySelector("#incumbent");
+const currentIframe = document.querySelector("#current");
+
+window.addEventListener("load", () => {
+  promise_test(async () => {
+    // This will invoke the constructor from currentIframe, but with incumbentIframe as the incumbent.
+    const messageChannel = incumbentIframe.contentWindow.createMessageChannel();
+
+    await new Promise((resolve, reject) => {
+      incumbentIframe.onload = () => resolve();
+      incumbentIframe.onerror = () => reject(new Error("Could not navigate the iframe"));
+      incumbentIframe.src = "/common/blank.html";
+    });
+
+    await new Promise((resolve, reject) => {
+      messageChannel.port1.onmessage = () => resolve();
+      messageChannel.port1.onmessageerror = () => reject("messageerror event recieved");
+      messageChannel.port2.postMessage("boo");
+    });
+  });
+});
+</script>
diff --git a/testing/web-platform/tests/webmessaging/multi-globals/support/current-document-domain.sub.html b/testing/web-platform/tests/webmessaging/multi-globals/support/current-document-domain.sub.html
new file mode 100644
index 0000000000..1b15f72ca4
--- /dev/null
+++ b/testing/web-platform/tests/webmessaging/multi-globals/support/current-document-domain.sub.html
@@ -0,0 +1,10 @@
+<!DOCTYPE html>
+<meta charset="utf-8">
+<title>Current page used as a test helper</title>
+
+<h1>Current</h1>
+
+<script>
+"use strict";
+document.domain = "{{hosts[][]}}";
+</script>
diff --git a/testing/web-platform/tests/webmessaging/multi-globals/support/current.html b/testing/web-platform/tests/webmessaging/multi-globals/support/current.html
new file mode 100644
index 0000000000..d05709dd43
--- /dev/null
+++ b/testing/web-platform/tests/webmessaging/multi-globals/support/current.html
@@ -0,0 +1,5 @@
+<!DOCTYPE html>
+<meta charset="utf-8">
+<title>Current page used as a test helper</title>
+
+<h1>Current</h1>
diff --git a/testing/web-platform/tests/webmessaging/multi-globals/support/incumbent-document-domain.sub.html b/testing/web-platform/tests/webmessaging/multi-globals/support/incumbent-document-domain.sub.html
new file mode 100644
index 0000000000..4791c29be7
--- /dev/null
+++ b/testing/web-platform/tests/webmessaging/multi-globals/support/incumbent-document-domain.sub.html
@@ -0,0 +1,14 @@
+<!DOCTYPE html>
+<meta charset="utf-8">
+<title>Incumbent page used as a test helper</title>
+
+<h1>Incumbent</h1>
+
+<script>
+"use strict";
+document.domain = "{{hosts[][]}}";
+
+window.createBroadcastChannel = (...args) => {
+  return new parent.frames[1].BroadcastChannel(...args);
+};
+</script>
diff --git a/testing/web-platform/tests/webmessaging/multi-globals/support/incumbent.html b/testing/web-platform/tests/webmessaging/multi-globals/support/incumbent.html
new file mode 100644
index 0000000000..a06e93c7ab
--- /dev/null
+++ b/testing/web-platform/tests/webmessaging/multi-globals/support/incumbent.html
@@ -0,0 +1,13 @@
+<!DOCTYPE html>
+<meta charset="utf-8">
+<title>Incumbent page used as a test helper</title>
+
+<h1>Incumbent</h1>
+
+<script>
+"use strict";
+
+window.createMessageChannel = () => {
+  return new parent.frames[1].MessageChannel();
+};
+</script>
diff --git a/testing/web-platform/tests/webmessaging/postMessage_ArrayBuffer.sub.htm b/testing/web-platform/tests/webmessaging/postMessage_ArrayBuffer.sub.htm
new file mode 100644
index 0000000000..457cf94fa5
--- /dev/null
+++ b/testing/web-platform/tests/webmessaging/postMessage_ArrayBuffer.sub.htm
@@ -0,0 +1,44 @@
+<!DOCTYPE html>
+<html>
+<head>
+<title> postMessage with ArrayBuffer object </title>
+<script src="/resources/testharness.js"></script>
+<script src="/resources/testharnessreport.js"></script>
+</head>
+<body>
+<div id=log></div>
+
+<div style="display:none">
+    <iframe width="70%" onload="PostMessageTest()" src="{{location[scheme]}}://{{domains[www]}}:{{location[port]}}/webmessaging/support/ChildWindowPostMessage.htm"></iframe>
+</div>
+
+<script>
+
+
+    var description = "Test Description: postMessage with ArrayBuffer object.";
+
+    var t = async_test(description);
+
+    var DATA;
+    var TYPE = "object";
+    var TARGET = document.querySelector("iframe");
+
+    function PostMessageTest()
+    {
+        test(function()
+        {
+            DATA = new ArrayBuffer(32);
+            TARGET.contentWindow.postMessage(DATA, "*");
+        }, "ArrayBuffer is supported.");
+    }
+
+    window.onmessage = t.step_func(function(e)
+    {
+        assert_equals(typeof(e.data), TYPE);
+        assert_equals(e.data.toString(), DATA.toString());
+        assert_equals(e.data.byteLength, 32);
+        t.done();
+    });
+</script>
+</body>
+</html>
diff --git a/testing/web-platform/tests/webmessaging/postMessage_CryptoKey_insecure.sub.html b/testing/web-platform/tests/webmessaging/postMessage_CryptoKey_insecure.sub.html
new file mode 100644
index 0000000000..8e5bdcb9c6
--- /dev/null
+++ b/testing/web-platform/tests/webmessaging/postMessage_CryptoKey_insecure.sub.html
@@ -0,0 +1,20 @@
+<!DOCTYPE html>
+<body>
+<script src="/resources/testharness.js"></script>
+<script src="/resources/testharnessreport.js"></script>
+<script>
+promise_test(async t => {
+  let nextMessageEvent = new Promise((resolve, reject) => {
+    window.addEventListener('message', e => resolve(e));
+    window.addEventListener('messageerror', e => resolve(e));
+  });
+  let w = window.open('https://{{hosts[][]}}:{{ports[https][0]}}/webmessaging/resources/post-cryptokey-to-opener.html');
+  try {
+    let event = await nextMessageEvent;
+    assert_equals(event.type, 'messageerror');
+  } finally {
+    w.close();
+  }
+}, "insecure context should not receive an object for secure contexts only");
+</script>
+</body>
diff --git a/testing/web-platform/tests/webmessaging/postMessage_Date.sub.htm b/testing/web-platform/tests/webmessaging/postMessage_Date.sub.htm
new file mode 100644
index 0000000000..0f89738f3a
--- /dev/null
+++ b/testing/web-platform/tests/webmessaging/postMessage_Date.sub.htm
@@ -0,0 +1,40 @@
+<!DOCTYPE html>
+<html>
+<head>
+<title> postMessage with Date object </title>
+<script src="/resources/testharness.js"></script>
+<script src="/resources/testharnessreport.js"></script>
+</head>
+<body>
+<div id=log></div>
+
+<div style="display:none">
+    <iframe width="70%" onload="PostMessageTest()" src="{{location[scheme]}}://{{domains[www1]}}:{{location[port]}}/webmessaging/support/ChildWindowPostMessage.htm"></iframe>
+</div>
+
+<script>
+
+
+    var description = "Test Description: Messages can contain JavaScript values (e.g., Dates).";
+
+    var t = async_test(description);
+
+    var DATA = new Date();
+    var TYPE = "object";
+    var TARGET = document.querySelector("iframe");
+
+    function PostMessageTest()
+    {
+        TARGET.contentWindow.postMessage(DATA, "*");
+    }
+
+    window.onmessage = t.step_func(function(e)
+    {
+        assert_equals(typeof(e.data), TYPE);
+        assert_equals(e.data.valueOf(), DATA.valueOf());
+        assert_not_equals(e.data, DATA, "Object is cloned");
+        t.done();
+    });
+</script>
+</body>
+</html>
diff --git a/testing/web-platform/tests/webmessaging/postMessage_Document.htm b/testing/web-platform/tests/webmessaging/postMessage_Document.htm
new file mode 100644
index 0000000000..c00a09a865
--- /dev/null
+++ b/testing/web-platform/tests/webmessaging/postMessage_Document.htm
@@ -0,0 +1,36 @@
+<!DOCTYPE html>
+<html>
+<head>
+<title> postMessage with Document object </title>
+<script src="/resources/testharness.js"></script>
+<script src="/resources/testharnessreport.js"></script>
+</head>
+<body>
+<div id=log></div>
+
+<div style="display:none">
+    <iframe width="70%" onload="PostMessageTest()" src="./support/ChildWindowPostMessage.htm"></iframe>
+</div>
+
+<script>
+
+
+    var description = "Test Description: " +
+                      "postMessage with Document object: Throw a DataCloneError if message could not be cloned.";
+
+    var DATA = document;
+    var TARGET = document.querySelector("iframe");
+
+    function PostMessageTest()
+    {
+        test(function()
+        {
+            assert_throws_dom("DATA_CLONE_ERR", TARGET.contentWindow.DOMException, function()
+            {
+                TARGET.contentWindow.postMessage(DATA, "*");
+            });
+        }, description);
+    }
+</script>
+</body>
+</html>
diff --git a/testing/web-platform/tests/webmessaging/postMessage_Function.htm b/testing/web-platform/tests/webmessaging/postMessage_Function.htm
new file mode 100644
index 0000000000..3976cebb74
--- /dev/null
+++ b/testing/web-platform/tests/webmessaging/postMessage_Function.htm
@@ -0,0 +1,36 @@
+<!DOCTYPE html>
+<html>
+<head>
+<title> postMessage with Function object </title>
+<script src="/resources/testharness.js"></script>
+<script src="/resources/testharnessreport.js"></script>
+</head>
+<body>
+<div id=log></div>
+
+<div style="display:none">
+    <iframe width="70%" onload="PostMessageTest()" src="./support/ChildWindowPostMessage.htm"></iframe>
+</div>
+
+<script>
+
+
+    var description = "Test Description: " +
+                      "postMessage with Function object: Throw a DataCloneError if message could not be cloned.";
+
+    var DATA = new Function();
+    var TARGET = document.querySelector("iframe");
+
+    function PostMessageTest()
+    {
+        test(function()
+        {
+            assert_throws_dom("DATA_CLONE_ERR", TARGET.contentWindow.DOMException, function()
+            {
+                TARGET.contentWindow.postMessage(DATA, "*");
+            });
+        }, description);
+    }
+</script>
+</body>
+</html>
diff --git a/testing/web-platform/tests/webmessaging/postMessage_MessagePorts_sorigin.htm b/testing/web-platform/tests/webmessaging/postMessage_MessagePorts_sorigin.htm
new file mode 100644
index 0000000000..6526e972c4
--- /dev/null
+++ b/testing/web-platform/tests/webmessaging/postMessage_MessagePorts_sorigin.htm
@@ -0,0 +1,76 @@
+<!DOCTYPE html>
+<html>
+<head>
+<title> postMessage to same-origin iframe with MessagePort array [100 ports] </title>
+<script src="/resources/testharness.js"></script>
+<script src="/resources/testharnessreport.js"></script>
+</head>
+<body>
+<div id=log></div>
+
+<div style="display:none">
+    <iframe width="70%" onload="PostMessageTest()" src="./support/ChildWindowPostMessage.htm"></iframe>
+</div>
+
+<script>
+
+
+    var description = "Test Description: postMessage to same-origin iframe with MessagePort array containing 100 ports.";
+
+    var t = async_test(description);
+
+    var TOTALPORTS = 100;
+    var LocalPorts = [];
+    var RemotePorts = [];
+    var PassedResult = 0;
+    var sum = 0;
+    var TARGET = document.querySelector("iframe").contentWindow;
+
+    function PostMessageTest()
+    {
+        test(function()
+        {
+            assert_own_property(window, "MessageChannel", "window");
+
+            var channels = [];
+
+            for (var i=0; i<TOTALPORTS; i++)
+            {
+                channels[i] = new MessageChannel();
+                LocalPorts[i] = channels[i].port1;
+                LocalPorts[i].foo = i;
+                RemotePorts[i] = channels[i].port2;
+
+                LocalPorts[i].onmessage = t.step_func(function(e)
+                {
+                    assert_equals(e.target.foo, e.data);
+
+                    PassedResult++;
+                    sum += e.data;
+
+                    if (PassedResult == TOTALPORTS)
+                    {
+                        assert_equals(sum, 4950);
+                        t.done();
+                    }
+                });
+            }
+
+            TARGET.postMessage("ports", "*", RemotePorts);
+
+        }, "MessageChannel is supported.");
+    }
+
+    window.onmessage = function(e)
+    {
+        if (e.data === "ports")
+        {
+            for (var i=0; i<TOTALPORTS; i++)
+            {
+                LocalPorts[i].postMessage(LocalPorts[i].foo);
+            }
+        }
+    }
+</script>
+</body>
+</html>
diff --git a/testing/web-platform/tests/webmessaging/postMessage_MessagePorts_xorigin.sub.htm b/testing/web-platform/tests/webmessaging/postMessage_MessagePorts_xorigin.sub.htm
new file mode 100644
index 0000000000..cf2b8eb4c1
--- /dev/null
+++ b/testing/web-platform/tests/webmessaging/postMessage_MessagePorts_xorigin.sub.htm
@@ -0,0 +1,76 @@
+<!DOCTYPE html>
+<html>
+<head>
+<title> postMessage to cross-origin iframe with MessagePort array [100 ports] </title>
+<script src="/resources/testharness.js"></script>
+<script src="/resources/testharnessreport.js"></script>
+</head>
+<body>
+<div id=log></div>
+
+<div style="display:none">
+    <iframe width="70%" onload="PostMessageTest()" src="{{location[scheme]}}://{{domains[www1]}}:{{location[port]}}/webmessaging/support/ChildWindowPostMessage.htm"></iframe>
+</div>
+
+<script>
+
+
+    var description = "Test Description: postMessage to cross-origin iframe with MessagePort array containing 100 ports.";
+
+    var t = async_test(description);
+
+    var TOTALPORTS = 100;
+    var LocalPorts = [];
+    var RemotePorts = [];
+    var PassedResult = 0;
+    var sum = 0;
+    var TARGET = document.querySelector("iframe").contentWindow;
+
+    function PostMessageTest()
+    {
+        test(function()
+        {
+            assert_own_property(window, "MessageChannel", "window");
+
+            var channels = [];
+
+            for (var i=0; i<TOTALPORTS; i++)
+            {
+                channels[i] = new MessageChannel();
+                LocalPorts[i] = channels[i].port1;
+                LocalPorts[i].foo = i;
+                RemotePorts[i] = channels[i].port2;
+
+                LocalPorts[i].onmessage = t.step_func(function(e)
+                {
+                    assert_equals(e.target.foo, e.data);
+
+                    PassedResult++;
+                    sum += e.data;
+
+                    if (PassedResult == TOTALPORTS)
+                    {
+                        assert_equals(sum, 4950);
+                        t.done();
+                    }
+                });
+            }
+
+            TARGET.postMessage("ports", "*", RemotePorts);
+
+        }, "MessageChannel is supported.");
+    }
+
+    window.onmessage = function(e)
+    {
+        if (e.data === "ports")
+        {
+            for (var i=0; i<TOTALPORTS; i++)
+            {
+                LocalPorts[i].postMessage(LocalPorts[i].foo);
+            }
+        }
+    }
+</script>
+</body>
+</html>
diff --git a/testing/web-platform/tests/webmessaging/postMessage_MessagePorts_xsite.sub.window.js b/testing/web-platform/tests/webmessaging/postMessage_MessagePorts_xsite.sub.window.js
new file mode 100644
index 0000000000..ca1e510eda
--- /dev/null
+++ b/testing/web-platform/tests/webmessaging/postMessage_MessagePorts_xsite.sub.window.js
@@ -0,0 +1,66 @@
+// META: script=/common/get-host-info.sub.js
+
+async_test(function(t) {
+    var host = get_host_info();
+    var noteSameSiteURL = host.HTTP_NOTSAMESITE_ORIGIN + "/webmessaging/support/ChildWindowPostMessage.htm";
+    var TOTALPORTS = 100;
+    var LocalPorts = [];
+    var RemotePorts = [];
+    var PassedResult = 0;
+    var sum = 0;
+    let iframe = document.createElement('iframe');
+    iframe.src = noteSameSiteURL;
+    document.body.appendChild(iframe);
+    var TARGET = document.querySelector("iframe").contentWindow;
+    iframe.onload = t.step_func(function() {
+        assert_own_property(window, "MessageChannel", "window");
+
+        var channels = [];
+
+        for (var i=0; i<TOTALPORTS; i++)
+        {
+            channels[i] = new MessageChannel();
+            LocalPorts[i] = channels[i].port1;
+            LocalPorts[i].foo = i;
+            RemotePorts[i] = channels[i].port2;
+
+            LocalPorts[i].onmessage = t.step_func(function(e)
+            {
+                assert_equals(e.target.foo, e.data);
+
+                PassedResult++;
+                sum += e.data;
+
+                if (PassedResult == TOTALPORTS)
+                {
+                    assert_equals(sum, 4950);
+                    t.done();
+                }
+            });
+        }
+        // Sending in two batches, to test the two postMessage variants.
+        var firstBatch = RemotePorts.slice(0, 50);
+        var secondBatch = RemotePorts.slice(50, 100);
+        TARGET.postMessage("ports", "*", firstBatch);
+        TARGET.postMessage("ports", {targetOrigin: '*', transfer: secondBatch});
+    });
+    var counter = 0;
+    window.onmessage = function(e)
+    {
+        if (e.data === "ports")
+        {
+            if (counter == 0) {
+                for (var i=0; i<51; i++)
+                {
+                    LocalPorts[i].postMessage(LocalPorts[i].foo);
+                }
+                counter = 1;
+            } else {
+                for (var i=51; i<100; i++)
+                {
+                    LocalPorts[i].postMessage(LocalPorts[i].foo);
+                }
+            }
+        }
+    }
+}, "Test Description: postMessage to cross-site iframe with MessagePort array containing 100 ports.");
diff --git a/testing/web-platform/tests/webmessaging/postMessage_arrays.sub.htm b/testing/web-platform/tests/webmessaging/postMessage_arrays.sub.htm
new file mode 100644
index 0000000000..41e4a75eda
--- /dev/null
+++ b/testing/web-platform/tests/webmessaging/postMessage_arrays.sub.htm
@@ -0,0 +1,39 @@
+<!DOCTYPE html>
+<html>
+<head>
+<title> postMessage with arrays </title>
+<script src="/resources/testharness.js"></script>
+<script src="/resources/testharnessreport.js"></script>
+</head>
+<body>
+<div id=log></div>
+
+<div style="display:none">
+    <iframe width="70%" onload="PostMessageTest()" src="{{location[scheme]}}://{{domains[www]}}:{{location[port]}}/webmessaging/support/ChildWindowPostMessage.htm"></iframe>
+</div>
+
+<script>
+
+
+    var description = "Test Description: Messages can be structured objects, e.g., arrays.";
+
+    var t = async_test(description);
+
+    var DATA = [1,2,3,4,5,6,7,8];
+    var TYPE = "object";
+    var TARGET = document.querySelector("iframe");
+
+    function PostMessageTest()
+    {
+        TARGET.contentWindow.postMessage(DATA, "*");
+    }
+
+    window.onmessage = t.step_func(function(e)
+    {
+        assert_equals(typeof(e.data), TYPE);
+        assert_array_equals(e.data, DATA);
+        t.done();
+    });
+</script>
+</body>
+</html>
diff --git a/testing/web-platform/tests/webmessaging/postMessage_asterisk_xorigin.sub.htm b/testing/web-platform/tests/webmessaging/postMessage_asterisk_xorigin.sub.htm
new file mode 100644
index 0000000000..2fab9431ef
--- /dev/null
+++ b/testing/web-platform/tests/webmessaging/postMessage_asterisk_xorigin.sub.htm
@@ -0,0 +1,52 @@
+<!DOCTYPE html>
+<html>
+<head>
+<title> Cross-origin postMessage with targetOrigin == "*" </title>
+<script src="/resources/testharness.js"></script>
+<script src="/resources/testharnessreport.js"></script>
+</head>
+<body>
+<div id=log></div>
+
+<script>
+
+
+    var description = "Test Description: To send the message to the target regardless of origin, set the target origin to '*'.";
+
+    var t = async_test(description);
+
+    var PORT = location.port !== "" ? ":" + location.port : "";
+    var XORIGIN = "{{location[scheme]}}://{{domains[www]}}" + PORT;
+    var SORIGIN = "{{location[scheme]}}://{{host}}" + PORT;
+    var ExpectedResult = ["#1", XORIGIN, "#2", SORIGIN];
+    var ActualResult = [];
+
+    window.onmessage = t.step_func(function(e)
+    {
+        // Messages from TARGET1 and TARGET2 can come in any order
+        // (since one of them is cross-origin and can run in parallel).
+        // To make the tests immune to message reordering, always
+        // put the response from TARGET1 at the start of the list.
+        if (e.data.toString() === "#1")
+        {
+            ActualResult = [e.data, e.origin].concat(ActualResult);
+        }
+        else if (e.data.toString() === "#2")
+        {
+            ActualResult = ActualResult.concat([e.data, e.origin]);
+        }
+
+        if (ActualResult.length >= ExpectedResult.length)
+        {
+            assert_array_equals(ActualResult, ExpectedResult, "ActualResult");
+            t.done();
+        }
+    });
+</script>
+
+<div style="display:none">
+    <iframe width="70%" onload="this.contentWindow.postMessage('#1', '*')" src="{{location[scheme]}}://{{domains[www]}}:{{location[port]}}/webmessaging/support/ChildWindowPostMessage.htm"></iframe>
+    <iframe width="70%" onload="this.contentWindow.postMessage('#2', '*')" src="./support/ChildWindowPostMessage.htm"></iframe>
+</div>
+</body>
+</html>
diff --git a/testing/web-platform/tests/webmessaging/postMessage_crosssite.sub.htm b/testing/web-platform/tests/webmessaging/postMessage_crosssite.sub.htm
new file mode 100644
index 0000000000..25bccd9df2
--- /dev/null
+++ b/testing/web-platform/tests/webmessaging/postMessage_crosssite.sub.htm
@@ -0,0 +1,29 @@
+<!DOCTYPE html>
+<script src="/resources/testharness.js"></script>
+<script src="/resources/testharnessreport.js"></script>
+<body>
+<script>
+async function addIframeAndReceiveMessage(path) {
+  let url = new URL('resources/transfer-arraybuffer-to-parent.html', location);
+  url.hostname = '{{hosts[alt][]}}';
+
+  let frame = document.createElement('iframe');
+  try {
+    frame.src = url;
+    document.body.appendChild(frame);
+    return await new Promise((resolve, reject) => {
+      window.addEventListener('message', e => resolve(e));
+      window.addEventListener('messageerror', e => reject(new Error('received messageerror')));
+    });
+  } finally {
+    frame.remove();
+  }
+}
+
+promise_test(async () => {
+  let messageEvent = await addIframeAndReceiveMessage('resources/transfer-arraybuffer-to-parent.html');
+  assert_class_string(messageEvent.data, 'ArrayBuffer');
+  assert_array_equals(new Uint8Array(messageEvent.data), [42, 222]);
+}, "cross-site windows can send transferred ArrayBuffer");
+</script>
+</body>
diff --git a/testing/web-platform/tests/webmessaging/postMessage_dup_transfer_objects.htm b/testing/web-platform/tests/webmessaging/postMessage_dup_transfer_objects.htm
new file mode 100644
index 0000000000..ade9515d3a
--- /dev/null
+++ b/testing/web-platform/tests/webmessaging/postMessage_dup_transfer_objects.htm
@@ -0,0 +1,38 @@
+<!DOCTYPE html>
+<html>
+<head>
+<title> postMessage with duplicate transfer objects raises DataCloneError exception </title>
+<script src="/resources/testharness.js"></script>
+<script src="/resources/testharnessreport.js"></script>
+</head>
+<body>
+<div id=log></div>
+
+<div style="display:none">
+    <iframe width="70%" onload="PostMessageTest()" src="./support/ChildWindowPostMessage.htm"></iframe>
+</div>
+
+<script>
+
+
+    var description = "Test Description: " +
+                      "postMessage with duplicate transfer objects raises DataCloneError exception.";
+
+    var DATA = "ports";
+    var TARGET = document.querySelector("iframe");
+
+    function PostMessageTest()
+    {
+        test(function()
+        {
+            assert_throws_dom("DATA_CLONE_ERR", TARGET.contentWindow.DOMException, function()
+            {
+                assert_own_property(window, "MessageChannel", "window");
+                var channel = new MessageChannel();
+                TARGET.contentWindow.postMessage(DATA, "*", [channel.port1, channel.port1]);
+            });
+        }, description);
+    }
+</script>
+</body>
+</html>
diff --git a/testing/web-platform/tests/webmessaging/postMessage_invalid_targetOrigin.htm b/testing/web-platform/tests/webmessaging/postMessage_invalid_targetOrigin.htm
new file mode 100644
index 0000000000..e2b39df22d
--- /dev/null
+++ b/testing/web-platform/tests/webmessaging/postMessage_invalid_targetOrigin.htm
@@ -0,0 +1,38 @@
+<!DOCTYPE html>
+<html>
+<head>
+<title> postMessage with invalid targetOrigin raises SyntaxError exception </title>
+<script src="/resources/testharness.js"></script>
+<script src="/resources/testharnessreport.js"></script>
+</head>
+<body>
+<div id=log></div>
+
+<div style="display:none">
+    <iframe width="70%" onload="PostMessageTest()" src="./support/ChildWindowPostMessage.htm"></iframe>
+</div>
+
+<script>
+
+
+    var description = "Test Description: " +
+                      "If the value of the targetOrigin argument is neither a single U+002A ASTERISK character (*), " +
+                      "a single U+002F SOLIDUS character (/), nor an absolute URL, then throw a SyntaxError exception " +
+                      "and abort the overall set of steps.";
+
+    var DATA = "InvalidOrigin";
+    var TARGET = document.querySelector("iframe");
+
+    function PostMessageTest()
+    {
+        test(function()
+        {
+            assert_throws_dom("SYNTAX_ERR", TARGET.contentWindow.DOMException, function()
+            {
+                TARGET.contentWindow.postMessage(DATA, DATA);
+            });
+        }, description);
+    }
+</script>
+</body>
+</html>
diff --git a/testing/web-platform/tests/webmessaging/postMessage_objects.sub.htm b/testing/web-platform/tests/webmessaging/postMessage_objects.sub.htm
new file mode 100644
index 0000000000..dab207188a
--- /dev/null
+++ b/testing/web-platform/tests/webmessaging/postMessage_objects.sub.htm
@@ -0,0 +1,40 @@
+<!DOCTYPE html>
+<html>
+<head>
+<title> postMessage with nested objects </title>
+<script src="/resources/testharness.js"></script>
+<script src="/resources/testharnessreport.js"></script>
+</head>
+<body>
+<div id=log></div>
+
+<div style="display:none">
+    <iframe width="70%" onload="PostMessageTest()" src="{{location[scheme]}}://{{domains[www]}}:{{location[port]}}/webmessaging/support/ChildWindowPostMessage.htm"></iframe>
+</div>
+
+<script>
+
+
+    var description = "Test Description: Messages can be structured objects, e.g., nested objects.";
+
+    var t = async_test(description);
+
+    var DATA = {foo: {bar: "wow"}};
+    var TYPE = "object";
+    var TARGET = document.querySelector("iframe");
+
+    function PostMessageTest()
+    {
+        TARGET.contentWindow.postMessage(DATA, "*");
+    }
+
+    window.onmessage = t.step_func(function(e)
+    {
+        assert_equals(typeof(e.data), TYPE);
+        assert_equals(typeof(e.data.foo), TYPE);
+        assert_object_equals(e.data, DATA);
+        t.done();
+    });
+</script>
+</body>
+</html>
diff --git a/testing/web-platform/tests/webmessaging/postMessage_origin_mismatch.sub.htm b/testing/web-platform/tests/webmessaging/postMessage_origin_mismatch.sub.htm
new file mode 100644
index 0000000000..6c8ac8353a
--- /dev/null
+++ b/testing/web-platform/tests/webmessaging/postMessage_origin_mismatch.sub.htm
@@ -0,0 +1,51 @@
+<!DOCTYPE html>
+<html>
+<head>
+<title> Same-origin: Origin of the target window doesn't match the given origin </title>
+<script src="/resources/testharness.js"></script>
+<script src="/resources/testharnessreport.js"></script>
+</head>
+<body>
+<div id=log></div>
+
+<div style="display:none">
+    <iframe width="70%" onload="PostMessageTest()" src="./support/ChildWindowPostMessage.htm"></iframe>
+</div>
+
+<script>
+
+
+    var description = "Test Description: " +
+                      "Same-origin: If the origin of the target window doesn't match the given origin, " +
+                      "the message is discarded.";
+
+    var t = async_test(description);
+
+    var PORT = location.port !== "" ? ":" + location.port : "";
+    var TARGET = document.querySelector("iframe");
+    var XORIGIN = "{{location[scheme]}}://{{domains[www1]}}" + PORT;
+    var SORIGIN = "{{location[scheme]}}://{{host}}" + PORT;
+    var ExpectedResult = ["#0", SORIGIN, "#3", SORIGIN];
+    var ActualResult = [];
+
+    function PostMessageTest()
+    {
+        TARGET.contentWindow.postMessage("#0", SORIGIN);
+        TARGET.contentWindow.postMessage("#1", "http://www.invalid-domain.com");
+        TARGET.contentWindow.postMessage("#2", XORIGIN);
+        TARGET.contentWindow.postMessage("#3", "*");
+    }
+
+    window.onmessage = t.step_func(function(e)
+    {
+        ActualResult.push(e.data, e.origin);
+
+        if (ActualResult.length >= ExpectedResult.length)
+        {
+            assert_array_equals(ActualResult, ExpectedResult, "ActualResult");
+            t.done();
+        }
+    });
+</script>
+</body>
+</html>
diff --git a/testing/web-platform/tests/webmessaging/postMessage_origin_mismatch_xorigin.sub.htm b/testing/web-platform/tests/webmessaging/postMessage_origin_mismatch_xorigin.sub.htm
new file mode 100644
index 0000000000..d8e38e2919
--- /dev/null
+++ b/testing/web-platform/tests/webmessaging/postMessage_origin_mismatch_xorigin.sub.htm
@@ -0,0 +1,51 @@
+<!DOCTYPE html>
+<html>
+<head>
+<title> Cross-origin: Origin of the target window doesn't match the given origin </title>
+<script src="/resources/testharness.js"></script>
+<script src="/resources/testharnessreport.js"></script>
+</head>
+<body>
+<div id=log></div>
+
+<div style="display:none">
+    <iframe width="70%" onload="PostMessageTest()" src="{{location[scheme]}}://{{domains[www1]}}:{{location[port]}}/webmessaging/support/ChildWindowPostMessage.htm"></iframe>
+</div>
+
+<script>
+
+
+    var description = "Test Description: " +
+                      "Cross-origin: If the origin of the target window doesn't match the given origin, " +
+                      "the message is discarded.";
+
+    var t = async_test(description);
+
+    var PORT = location.port !== "" ? ":" + location.port : "";
+    var TARGET = document.querySelector("iframe");
+    var XORIGIN = "{{location[scheme]}}://{{domains[www1]}}" + PORT;
+    var SORIGIN = "{{location[scheme]}}://{{host}}" + PORT;
+    var ExpectedResult = ["#0", XORIGIN, "#3", XORIGIN];
+    var ActualResult = [];
+
+    function PostMessageTest()
+    {
+        TARGET.contentWindow.postMessage("#0", XORIGIN);
+        TARGET.contentWindow.postMessage("#1", "http://www.invalid-domain.com");
+        TARGET.contentWindow.postMessage("#2", SORIGIN);
+        TARGET.contentWindow.postMessage("#3", "*");
+    }
+
+    window.onmessage = t.step_func(function(e)
+    {
+        ActualResult.push(e.data, e.origin);
+
+        if (ActualResult.length >= ExpectedResult.length)
+        {
+            assert_array_equals(ActualResult, ExpectedResult, "ActualResult");
+            t.done();
+        }
+    });
+</script>
+</body>
+</html>
diff --git a/testing/web-platform/tests/webmessaging/postMessage_solidus_sorigin.htm b/testing/web-platform/tests/webmessaging/postMessage_solidus_sorigin.htm
new file mode 100644
index 0000000000..92f5afb798
--- /dev/null
+++ b/testing/web-platform/tests/webmessaging/postMessage_solidus_sorigin.htm
@@ -0,0 +1,43 @@
+<!DOCTYPE html>
+<html>
+<head>
+<title> Same-origin postMessage with targetOrigin == "/" </title>
+<script src="/resources/testharness.js"></script>
+<script src="/resources/testharnessreport.js"></script>
+</head>
+<body>
+<div id=log></div>
+
+<div style="display:none">
+    <iframe width="70%" onload="PostMessageTest()" src="./support/ChildWindowPostMessage.htm"></iframe>
+</div>
+
+<script>
+
+
+    var description = "Test Description: " +
+                      "To restrict the message to same-origin targets only, without needing to explicitly " +
+                      "state the origin, set the target origin to '/'.";
+
+    var t = async_test(description);
+
+    var DATA = "/";
+    var TARGET = document.querySelector("iframe");
+    var SORIGIN = location.protocol + "//" + location.host;
+    var ExpectedResult = [DATA, SORIGIN];
+    var ActualResult = [];
+
+    function PostMessageTest()
+    {
+        TARGET.contentWindow.postMessage(DATA, "/");
+    }
+
+    window.onmessage = t.step_func(function(e)
+    {
+        ActualResult.push(e.data, e.origin);
+        assert_array_equals(ActualResult, ExpectedResult, "ActualResult");
+        t.done();
+    });
+</script>
+</body>
+</html>
diff --git a/testing/web-platform/tests/webmessaging/postMessage_solidus_xorigin.sub.htm b/testing/web-platform/tests/webmessaging/postMessage_solidus_xorigin.sub.htm
new file mode 100644
index 0000000000..eebc85432f
--- /dev/null
+++ b/testing/web-platform/tests/webmessaging/postMessage_solidus_xorigin.sub.htm
@@ -0,0 +1,48 @@
+<!DOCTYPE html>
+<html>
+<head>
+<title> Cross-origin postMessage with targetOrigin == "/" </title>
+<script src="/resources/testharness.js"></script>
+<script src="/resources/testharnessreport.js"></script>
+</head>
+<body>
+<div id=log></div>
+
+<div style="display:none">
+    <iframe width="70%" onload="PostMessageTest()" src="{{location[scheme]}}://{{domains[www1]}}:{{location[port]}}/webmessaging/support/ChildWindowPostMessage.htm"></iframe>
+</div>
+
+<script>
+
+
+    var description = "Test Description: " +
+                      "If the targetOrigin argument is a single literal U+002F SOLIDUS character (/), and " +
+                      "the Document of the Window object on which the method was invoked does not have the " +
+                      "same origin as the entry script's document, then abort these steps silently.";
+
+    var t = async_test(description);
+
+    var DATA = "NoExceptionRaised";
+    var TARGET = document.querySelector("iframe");
+
+    function PostMessageTest()
+    {
+        try
+        {
+            TARGET.contentWindow.postMessage("/", "/");
+            TARGET.contentWindow.postMessage(DATA, "*");
+        }
+        catch(ex)
+        {
+            TARGET.contentWindow.postMessage("ExceptionRaised", "*");
+        }
+    }
+
+    window.onmessage = t.step_func(function(e)
+    {
+        assert_equals(e.data, DATA, "e.data");
+        t.done();
+    });
+</script>
+</body>
+</html>
diff --git a/testing/web-platform/tests/webmessaging/resources/post-cryptokey-to-opener.html b/testing/web-platform/tests/webmessaging/resources/post-cryptokey-to-opener.html
new file mode 100644
index 0000000000..91c70165f0
--- /dev/null
+++ b/testing/web-platform/tests/webmessaging/resources/post-cryptokey-to-opener.html
@@ -0,0 +1,6 @@
+<!DOCTYPE html>
+<script>
+crypto.subtle.generateKey({name: 'AES-CBC', length: 128}, false, ['encrypt', 'decrypt'])
+.then(key => opener.postMessage({key}, '*'))
+.catch(error => opener.postMessage({error: error.toString()}, '*'));
+</script>
diff --git a/testing/web-platform/tests/webmessaging/resources/transfer-arraybuffer-to-parent.html b/testing/web-platform/tests/webmessaging/resources/transfer-arraybuffer-to-parent.html
new file mode 100644
index 0000000000..97cff4dcb3
--- /dev/null
+++ b/testing/web-platform/tests/webmessaging/resources/transfer-arraybuffer-to-parent.html
@@ -0,0 +1,5 @@
+<!DOCTYPE html>
+<script>
+let ab = new Uint8Array([42, 222]).buffer;
+window.parent.postMessage(ab, '*', [ab]);
+</script>
diff --git a/testing/web-platform/tests/webmessaging/support/ChildWindowPostMessage.htm b/testing/web-platform/tests/webmessaging/support/ChildWindowPostMessage.htm
new file mode 100644
index 0000000000..13d4103a82
--- /dev/null
+++ b/testing/web-platform/tests/webmessaging/support/ChildWindowPostMessage.htm
@@ -0,0 +1,58 @@
+<!DOCTYPE html>
+<html>
+<head>
+    <title> Child window for Web Messaging tests </title>
+</head>
+<body>
+    <script>
+        if (window.opener)
+        {
+            window.onload = function()
+            {
+                try
+                {
+                    window.opener.postMessage("MSG_ONLOAD_FIRED", "*");
+                }
+                catch(ex)
+                {
+                    window.close();
+                }
+            }
+        }
+
+        window.onmessage = function(e)
+        {
+            try
+            {
+                if (typeof(e.data) == "object" && typeof(e.data.test) == "string")
+                {
+                    eval(e.data.test);
+                }
+                else if (e.data == "*" || e.data == "/")
+                {
+                    e.source.postMessage(e.data, e.data);
+                }
+                else
+                {
+                    e.source.postMessage(e.data, e.origin);
+                }
+
+                if (e.data == "ports")
+                {
+                    var total = e.ports.length;
+                    for (var i=0; i<total; i++)
+                    {
+                        e.ports[i].onmessage = function (evt)
+                        {
+                            evt.target.postMessage(evt.data);
+                        }
+                    }
+                }
+            }
+            catch(ex)
+            {
+            }
+        }
+    </script>
+</body>
+</html>
diff --git a/testing/web-platform/tests/webmessaging/support/MessageEvent-trusted-worker.js b/testing/web-platform/tests/webmessaging/support/MessageEvent-trusted-worker.js
new file mode 100644
index 0000000000..6e8c3a781b
--- /dev/null
+++ b/testing/web-platform/tests/webmessaging/support/MessageEvent-trusted-worker.js
@@ -0,0 +1,4 @@
+"use strict";
+
+const channel = new BroadcastChannel("channel name");
+channel.postMessage("ping");
diff --git a/testing/web-platform/tests/webmessaging/support/compare.js b/testing/web-platform/tests/webmessaging/support/compare.js
new file mode 100644
index 0000000000..5341b37438
--- /dev/null
+++ b/testing/web-platform/tests/webmessaging/support/compare.js
@@ -0,0 +1,39 @@
+function sameDate(d1, d2) {
+  return (d1 instanceof Date && d2 instanceof Date && d1.valueOf() == d2.valueOf());
+}
+
+function sameRE(r1, r2) {
+  return (r1 instanceof RegExp && r2 instanceof RegExp && r1.toString() == r2.toString());
+}
+
+function assert_array_equals_(observed, expected, msg) {
+  if (observed.length == expected.length) {
+    for (var i = 0; i < observed.length; i++) {
+      if (observed[i] instanceof Date) {
+        observed[i] = sameDate(observed[i], expected[i]);
+        expected[i] = true;
+      } else if (observed[i] instanceof RegExp) {
+        observed[i] = sameRE(observed[i], expected[i]);
+        expected[i] = true;
+      }
+    }
+  }
+
+  assert_array_equals(observed, expected, msg);
+}
+
+function assert_object_equals_(observed, expected, msg) {
+  for (var p in observed) {
+    if (observed[p] instanceof Date) {
+      observed[p] = sameDate(observed[p], expected[p]);
+      expected[p] = true;
+    } else if (observed[p] instanceof RegExp) {
+      observed[p] = sameRE(observed[p], expected[p]);
+      expected[p] = true;
+    } else if (observed[p] instanceof Array || String(observed[p]) === '[object Object]') {
+      observed[p] = String(observed[p]) === String(expected[p]);
+      expected[p] = true;
+    }
+    assert_equals(observed[p], expected[p], msg);
+  }
+}
diff --git a/testing/web-platform/tests/webmessaging/with-options/broken-origin.html b/testing/web-platform/tests/webmessaging/with-options/broken-origin.html
new file mode 100644
index 0000000000..795404b0ec
--- /dev/null
+++ b/testing/web-platform/tests/webmessaging/with-options/broken-origin.html
@@ -0,0 +1,12 @@
+<!doctype html>
+<title>resolving broken url</title>
+<script src="/resources/testharness.js"></script>
+<script src="/resources/testharnessreport.js"></script>
+<div id="log"></div>
+<script>
+test(function() {
+  assert_throws_dom('SYNTAX_ERR', function() {
+    postMessage('', {targetOrigin: 'http://foo bar'});
+  }, 'should have failed to resolve');
+});
+</script>
diff --git a/testing/web-platform/tests/webmessaging/with-options/host-specific-origin.html b/testing/web-platform/tests/webmessaging/with-options/host-specific-origin.html
new file mode 100644
index 0000000000..5003bcc807
--- /dev/null
+++ b/testing/web-platform/tests/webmessaging/with-options/host-specific-origin.html
@@ -0,0 +1,14 @@
+<!doctype html>
+<title>resolving url with stuff in host-specific</title>
+<script src="/resources/testharness.js"></script>
+<script src="/resources/testharnessreport.js"></script>
+<div id="log"></div>
+<script>
+async_test(function() {
+  postMessage('', {targetOrigin: location.protocol + '//' + location.host + '//'});
+  onmessage = this.step_func(function(e) {
+    assert_equals(e.origin, location.protocol + '//' + location.host);
+    this.done();
+  });
+});
+</script>
diff --git a/testing/web-platform/tests/webmessaging/with-options/message-channel-transferable.html b/testing/web-platform/tests/webmessaging/with-options/message-channel-transferable.html
new file mode 100644
index 0000000000..d42db10695
--- /dev/null
+++ b/testing/web-platform/tests/webmessaging/with-options/message-channel-transferable.html
@@ -0,0 +1,15 @@
+<!doctype html>
+<title>message channel as ports</title>
+<script src="/resources/testharness.js"></script>
+<script src="/resources/testharnessreport.js"></script>
+<div id=log></div>
+<script>
+async_test(function(t) {
+  var channel = new MessageChannel();
+  postMessage('', {targetOrigin: '*', transfer: [channel.port1, channel.port2]});
+  onmessage = t.step_func(function(e) {
+    assert_equals(e.ports.length, 2);
+    t.done();
+  });
+}, "MessageChannel's ports as MessagePort objects");
+</script>
diff --git a/testing/web-platform/tests/webmessaging/with-options/no-target-origin.html b/testing/web-platform/tests/webmessaging/with-options/no-target-origin.html
new file mode 100644
index 0000000000..517466cc4c
--- /dev/null
+++ b/testing/web-platform/tests/webmessaging/with-options/no-target-origin.html
@@ -0,0 +1,14 @@
+<!doctype html>
+<title>no targetOrigin</title>
+<script src="/resources/testharness.js"></script>
+<script src="/resources/testharnessreport.js"></script>
+<div id="log"></div>
+<script>
+async_test(function() {
+  postMessage('', {});
+  onmessage = this.step_func(function(e) {
+    assert_equals(e.data, '');
+    this.done();
+  });
+});
+</script>
diff --git a/testing/web-platform/tests/webmessaging/with-options/null-transfer.html b/testing/web-platform/tests/webmessaging/with-options/null-transfer.html
new file mode 100644
index 0000000000..2ea09eb7ab
--- /dev/null
+++ b/testing/web-platform/tests/webmessaging/with-options/null-transfer.html
@@ -0,0 +1,10 @@
+<!doctype html>
+<title>null transfer</title>
+<script src="/resources/testharness.js"></script>
+<script src="/resources/testharnessreport.js"></script>
+<div id=log></div>
+<script>
+test(function(t) {
+  assert_throws_js(TypeError, () => postMessage('', {transfer: null}));
+});
+</script>
diff --git a/testing/web-platform/tests/webmessaging/with-options/one-arg.html b/testing/web-platform/tests/webmessaging/with-options/one-arg.html
new file mode 100644
index 0000000000..8246e55f31
--- /dev/null
+++ b/testing/web-platform/tests/webmessaging/with-options/one-arg.html
@@ -0,0 +1,13 @@
+<!doctype html>
+<title>just one argument</title>
+<script src="/resources/testharness.js"></script>
+<script src="/resources/testharnessreport.js"></script>
+<div id="log"></div>
+<script>
+async_test(t => {
+  postMessage('');
+  onmessage = t.step_func_done(e => {
+    assert_equals(e.data, '');
+  });
+});
+</script>
diff --git a/testing/web-platform/tests/webmessaging/with-options/slash-origin.html b/testing/web-platform/tests/webmessaging/with-options/slash-origin.html
new file mode 100644
index 0000000000..8bfde73774
--- /dev/null
+++ b/testing/web-platform/tests/webmessaging/with-options/slash-origin.html
@@ -0,0 +1,14 @@
+<!doctype html>
+<title>special value '/'</title>
+<script src="/resources/testharness.js"></script>
+<script src="/resources/testharnessreport.js"></script>
+<div id="log"></div>
+<script>
+async_test(function() {
+  postMessage('', {targetOrigin: '/'});
+  onmessage = this.step_func(function(e) {
+    assert_equals(e.data, '');
+    this.done();
+  });
+});
+</script>
diff --git a/testing/web-platform/tests/webmessaging/with-options/undefined-transferable.html b/testing/web-platform/tests/webmessaging/with-options/undefined-transferable.html
new file mode 100644
index 0000000000..a123b7d9bd
--- /dev/null
+++ b/testing/web-platform/tests/webmessaging/with-options/undefined-transferable.html
@@ -0,0 +1,14 @@
+<!doctype html>
+<title>undefined as transferable</title>
+<script src="/resources/testharness.js"></script>
+<script src="/resources/testharnessreport.js"></script>
+<div id=log></div>
+<script>
+async_test(function() {
+  postMessage('', {transfer: undefined});
+  onmessage = this.step_func(function(e) {
+    assert_array_equals(e.ports, []);
+    this.done();
+  });
+});
+</script>
diff --git a/testing/web-platform/tests/webmessaging/with-options/unknown-parameter.html b/testing/web-platform/tests/webmessaging/with-options/unknown-parameter.html
new file mode 100644
index 0000000000..de050e74f5
--- /dev/null
+++ b/testing/web-platform/tests/webmessaging/with-options/unknown-parameter.html
@@ -0,0 +1,14 @@
+<!doctype html>
+<title>unknown parameter</title>
+<script src="/resources/testharness.js"></script>
+<script src="/resources/testharnessreport.js"></script>
+<div id="log"></div>
+<script>
+async_test(function() {
+  postMessage('', {someBogusParameterOnThisDictionary: 'food'});
+  onmessage = this.step_func(function(e) {
+    assert_equals(e.data, '');
+    this.done();
+  });
+});
+</script>
diff --git a/testing/web-platform/tests/webmessaging/with-ports/001.html b/testing/web-platform/tests/webmessaging/with-ports/001.html
new file mode 100644
index 0000000000..62dcf5e9bf
--- /dev/null
+++ b/testing/web-platform/tests/webmessaging/with-ports/001.html
@@ -0,0 +1,12 @@
+<!doctype html>
+<title>resolving broken url</title>
+<script src="/resources/testharness.js"></script>
+<script src="/resources/testharnessreport.js"></script>
+<div id="log"></div>
+<script>
+test(function() {
+  assert_throws_dom('SYNTAX_ERR', function() {
+    postMessage('', 'http://foo bar', []);
+  }, 'should have failed to resolve');
+});
+</script>
diff --git a/testing/web-platform/tests/webmessaging/with-ports/002.html b/testing/web-platform/tests/webmessaging/with-ports/002.html
new file mode 100644
index 0000000000..f7d085937c
--- /dev/null
+++ b/testing/web-platform/tests/webmessaging/with-ports/002.html
@@ -0,0 +1,14 @@
+<!doctype html>
+<title>resolving url with stuff in host-specific</title>
+<script src="/resources/testharness.js"></script>
+<script src="/resources/testharnessreport.js"></script>
+<div id="log"></div>
+<script>
+async_test(function() {
+  postMessage('', location.protocol + '//' + location.host + '//', []);
+  onmessage = this.step_func(function(e) {
+    assert_equals(e.origin, location.protocol + '//' + location.host);
+    this.done();
+  });
+});
+</script>
diff --git a/testing/web-platform/tests/webmessaging/with-ports/003.html b/testing/web-platform/tests/webmessaging/with-ports/003.html
new file mode 100644
index 0000000000..47ddfbe81a
--- /dev/null
+++ b/testing/web-platform/tests/webmessaging/with-ports/003.html
@@ -0,0 +1,12 @@
+<!doctype html>
+<title>resolving 'example.org'</title>
+<script src="/resources/testharness.js"></script>
+<script src="/resources/testharnessreport.js"></script>
+<div id="log"></div>
+<script>
+test(function() {
+  assert_throws_dom('SYNTAX_ERR', function() {
+    postMessage('', 'example.org', []);
+  }, 'targetOrigin is not an absolute url');
+});
+</script>
diff --git a/testing/web-platform/tests/webmessaging/with-ports/004.html b/testing/web-platform/tests/webmessaging/with-ports/004.html
new file mode 100644
index 0000000000..d129ad119a
--- /dev/null
+++ b/testing/web-platform/tests/webmessaging/with-ports/004.html
@@ -0,0 +1,14 @@
+<!doctype html>
+<title>special value '/'</title>
+<script src="/resources/testharness.js"></script>
+<script src="/resources/testharnessreport.js"></script>
+<div id="log"></div>
+<script>
+async_test(function() {
+  postMessage('', '/', []);
+  onmessage = this.step_func(function(e) {
+    assert_equals(e.data, '');
+    this.done();
+  });
+});
+</script>
diff --git a/testing/web-platform/tests/webmessaging/with-ports/005.html b/testing/web-platform/tests/webmessaging/with-ports/005.html
new file mode 100644
index 0000000000..e803968919
--- /dev/null
+++ b/testing/web-platform/tests/webmessaging/with-ports/005.html
@@ -0,0 +1,14 @@
+<!doctype html>
+<title>resolving a same origin targetOrigin</title>
+<script src="/resources/testharness.js"></script>
+<script src="/resources/testharnessreport.js"></script>
+<div id="log"></div>
+<script>
+async_test(function() {
+  postMessage('', location.protocol + '//' + location.host, []);
+  onmessage = this.step_func(function(e) {
+    assert_equals(e.data, '');
+    this.done();
+  });
+});
+</script>
diff --git a/testing/web-platform/tests/webmessaging/with-ports/006.html b/testing/web-platform/tests/webmessaging/with-ports/006.html
new file mode 100644
index 0000000000..4e3f1ede84
--- /dev/null
+++ b/testing/web-platform/tests/webmessaging/with-ports/006.html
@@ -0,0 +1,14 @@
+<!doctype html>
+<title>resolving a same origin targetOrigin with trailing slash</title>
+<script src="/resources/testharness.js"></script>
+<script src="/resources/testharnessreport.js"></script>
+<div id="log"></div>
+<script>
+async_test(function() {
+  postMessage('', location.protocol + '//' + location.host + '/', []);
+  onmessage = this.step_func(function(e) {
+    assert_equals(e.data, '');
+    this.done();
+  });
+});
+</script>
diff --git a/testing/web-platform/tests/webmessaging/with-ports/007.html b/testing/web-platform/tests/webmessaging/with-ports/007.html
new file mode 100644
index 0000000000..c049a1337d
--- /dev/null
+++ b/testing/web-platform/tests/webmessaging/with-ports/007.html
@@ -0,0 +1,14 @@
+<!doctype html>
+<title>targetOrigin '*'</title>
+<script src="/resources/testharness.js"></script>
+<script src="/resources/testharnessreport.js"></script>
+<div id="log"></div>
+<script>
+async_test(function() {
+  postMessage('', '*', []);
+  onmessage = this.step_func(function(e) {
+    assert_equals(e.data, '');
+    this.done();
+  });
+});
+</script>
diff --git a/testing/web-platform/tests/webmessaging/with-ports/010.html b/testing/web-platform/tests/webmessaging/with-ports/010.html
new file mode 100644
index 0000000000..05080e3f7a
--- /dev/null
+++ b/testing/web-platform/tests/webmessaging/with-ports/010.html
@@ -0,0 +1,113 @@
+<!doctype html>
+<title>message clone</title>
+<script src="/resources/testharness.js"></script>
+<script src="/resources/testharnessreport.js"></script>
+<script src="../support/compare.js"></script>
+<div id=log></div>
+<script>
+  var err = new Error('foo');
+  var date = new Date();
+
+  var test_array = [ undefined,
+                     null,
+                     false,
+                     true,
+                     1,
+                     NaN,
+                     Infinity,
+                     'foo',
+                     date,
+                     /foo/,
+                     null/*self*/,
+                     null/*err*/];
+
+  var cloned_array = [ undefined,
+                       null,
+                       false,
+                       true,
+                       1,
+                       NaN,
+                       Infinity,
+                       'foo',
+                       date,
+                       /foo/,
+                       null/*self*/,
+                       null/*err*/];
+
+  var test_object = {a: undefined,
+                     b: null,
+                     c: false,
+                     d: true,
+                     e: 1,
+                     f: NaN,
+                     g: Infinity,
+                     h: 'foo',
+                     i: date,
+                     j: /foo/,
+                     k: null/*self*/,
+                     l: [],
+                     m: {},
+                     n: null /*err*/};
+
+  var cloned_object = {a:undefined, b:null, c:false, d:true, e:1, f:NaN, g:Infinity, h:'foo', i: date, j: /foo/,  k:null, l: [], m: {}, n:null};
+
+  var tests = [undefined, null,
+               false, true,
+               1, NaN, Infinity,
+               'foo',
+               date,
+               /foo/,
+               /* ImageData, File, FileData, FileList, */
+               null /*self*/,
+               test_array,
+               test_object,
+               null /*err*/];
+
+  for (var i = 0; i < tests.length; ++i) {
+    postMessage(tests[i], '*', []);
+  }
+
+  var test_undefined = async_test('undefined');
+  var test_null = async_test('null');
+  var test_false = async_test('false');
+  var test_true = async_test('true');
+  var test_1 = async_test('1');
+  var test_NaN = async_test('NaN');
+  var test_Infinity = async_test('Infinity');
+  var test_string = async_test('string');
+  var test_date = async_test('date');
+  var test_regex = async_test('regex');
+  var test_self = async_test('self');
+  var test_array = async_test('array');
+  var test_object = async_test('object');
+  var test_error = async_test('error');
+  var test_unreached = async_test('unreached');
+
+  var j = 0;
+  onmessage = function(e) {
+    switch (j) {
+      case 0: test_undefined.step(function() { assert_equals(e.data, undefined); this.done(); }); break;
+      case 1: test_null.step(function() { assert_equals(e.data, null); this.done(); }); break;
+      case 2: test_false.step(function() { assert_false(e.data); this.done(); }); break;
+      case 3: test_true.step(function() { assert_true(e.data); this.done(); }); break;
+      case 4: test_1.step(function() { assert_equals(e.data, 1); this.done(); }); break;
+      case 5: test_NaN.step(function() { assert_equals(e.data, NaN); this.done(); }); break;
+      case 6: test_Infinity.step(function() { assert_equals(e.data, Infinity); this.done(); }); break;
+      case 7: test_string.step(function() { assert_equals(e.data, 'foo'); this.done(); }); break;
+      case 8: test_date.step(function() { assert_true(sameDate(e.data, date)); this.done(); }); break;
+      case 9: test_regex.step(function() { assert_equals('' + e.data, '/foo/'); assert_equals(e.data instanceof RegExp, true, 'e.data instanceof RegExp'); this.done(); }); break;
+      // not testing it any more, as cloning host objects will now raise exceptions. TODO: add (exceptional) tests for these.
+      case 10: test_self.step(function() { assert_equals(e.data, null); this.done(); }); break;
+      case 11: test_array.step(function() { assert_array_equals_(e.data, cloned_array, 'array'); this.done(); }); break;
+      case 12: test_object.step(function() { assert_object_equals_(e.data, cloned_object, 'object'); this.done(); }); break;
+      case 13:
+        test_error.step(function() { assert_equals(e.data, null, 'new Error()'); this.done(); });
+        setTimeout(test_unreached.step_func(function() { assert_equals(j, 14); this.done(); }), 50);
+        break;
+      default: test_unreached.step(function() { assert_unreached('got an unexpected message event ('+j+')'); });
+    };
+    j++;
+  }
+
+
+</script>
diff --git a/testing/web-platform/tests/webmessaging/with-ports/011.html b/testing/web-platform/tests/webmessaging/with-ports/011.html
new file mode 100644
index 0000000000..782b3208ba
--- /dev/null
+++ b/testing/web-platform/tests/webmessaging/with-ports/011.html
@@ -0,0 +1,29 @@
+<!doctype html>
+<title>posting an imagedata (from a cloned canvas) in an array</title>
+<script src="/resources/testharness.js"></script>
+<script src="/resources/testharnessreport.js"></script>
+<div id="log"></div>
+<script>
+async_test(function() {
+
+  var canvas = document.createElement('canvas');
+  var clone = canvas.cloneNode(true);
+  var ctx = clone.getContext('2d');
+  var imagedata = ctx.getImageData(0, 0, 300, 150);
+  postMessage([imagedata], '*', []);
+
+  onmessage = this.step_func(function(e) {
+    function processPixels(imagedata) {
+      var pixeldata = imagedata.data;
+      for (var i = 0; i < pixeldata.length; i = i+4) {
+        pixeldata[i] = 128;
+        assert_equals(pixeldata[i], 128);
+      }
+    }
+    processPixels(e.data[0]);
+    this.done();
+  });
+
+});
+</script>
+
diff --git a/testing/web-platform/tests/webmessaging/with-ports/012.html b/testing/web-platform/tests/webmessaging/with-ports/012.html
new file mode 100644
index 0000000000..6efe4c114a
--- /dev/null
+++ b/testing/web-platform/tests/webmessaging/with-ports/012.html
@@ -0,0 +1,16 @@
+<!doctype html>
+<title>loop in array in structured clone</title>
+<script src="/resources/testharness.js"></script>
+<script src="/resources/testharnessreport.js"></script>
+<div id=log></div>
+<script>
+async_test(function() {
+  var x = [];
+  x[0] = x;
+  postMessage(x, '*', []);
+  onmessage = this.step_func(function(e) {
+    assert_equals(e.data, e.data[0]);
+    this.done();
+  });
+});
+</script>
diff --git a/testing/web-platform/tests/webmessaging/with-ports/013.html b/testing/web-platform/tests/webmessaging/with-ports/013.html
new file mode 100644
index 0000000000..248958ea10
--- /dev/null
+++ b/testing/web-platform/tests/webmessaging/with-ports/013.html
@@ -0,0 +1,17 @@
+<!doctype html>
+<title>loop in object in structured clone</title>
+<script src="/resources/testharness.js"></script>
+<script src="/resources/testharnessreport.js"></script>
+<div id="log"></div>
+<script>
+async_test(function() {
+  var x = {};
+  x.foo = x;
+  postMessage(x, '*', []);
+  onmessage = this.step_func(function(e) {
+    assert_equals(e.data, e.data.foo);
+    this.done();
+  });
+});
+</script>
+
diff --git a/testing/web-platform/tests/webmessaging/with-ports/014.html b/testing/web-platform/tests/webmessaging/with-ports/014.html
new file mode 100644
index 0000000000..3c970c42ad
--- /dev/null
+++ b/testing/web-platform/tests/webmessaging/with-ports/014.html
@@ -0,0 +1,17 @@
+<!doctype html>
+<title>structured clone vs reference</title>
+<script src="/resources/testharness.js"></script>
+<script src="/resources/testharnessreport.js"></script>
+<div id="log"></div>
+<script>
+async_test(function(t) {
+  var x = [];
+  y = [x,x];
+  postMessage(y, '*', []);
+  onmessage = t.step_func(function(e) {
+    assert_equals(e.data[0], e.data[1], 'e.data[0] === e.data[1]');
+    assert_not_equals(e.data[0], x, 'e.data[0] !== x');
+    t.done();
+  });
+});
+</script>
diff --git a/testing/web-platform/tests/webmessaging/with-ports/015.html b/testing/web-platform/tests/webmessaging/with-ports/015.html
new file mode 100644
index 0000000000..a17c97be19
--- /dev/null
+++ b/testing/web-platform/tests/webmessaging/with-ports/015.html
@@ -0,0 +1,15 @@
+<!doctype html>
+<title>different origin</title>
+<script src="/resources/testharness.js"></script>
+<script src="/resources/testharnessreport.js"></script>
+<div id=log></div>
+<script>
+async_test(function() {
+  postMessage('', 'http://example.org', []);
+  onmessage = this.step_func(function(e) {
+    assert_unreached();
+  });
+  setTimeout(this.step_func(function(){ this.done(); }), 50);
+});
+</script>
+
diff --git a/testing/web-platform/tests/webmessaging/with-ports/016.html b/testing/web-platform/tests/webmessaging/with-ports/016.html
new file mode 100644
index 0000000000..51cadec7c1
--- /dev/null
+++ b/testing/web-platform/tests/webmessaging/with-ports/016.html
@@ -0,0 +1,23 @@
+<!doctype html>
+<title>origin of the script that invoked the method, data:</title>
+<script src="/resources/testharness.js"></script>
+<script src="/resources/testharnessreport.js"></script>
+<iframe src="data:text/html,<script>onmessage = function(e) { parent.postMessage(e.origin, '*'); }; parent.postMessage('loaded', '*');</script>"></iframe>
+<div id=log></div>
+<script>
+async_test(function() {
+  onmessage = this.step_func(function(e) {
+    if (e.data === 'loaded') {
+      window[0].postMessage('', '*');
+      return;
+    }
+
+    assert_equals(e.data, location.protocol + '//' + location.host);
+    assert_equals(e.origin, 'null');
+    assert_array_equals(e.ports, []);
+    this.done();
+  });
+});
+</script>
+
+
diff --git a/testing/web-platform/tests/webmessaging/with-ports/017.html b/testing/web-platform/tests/webmessaging/with-ports/017.html
new file mode 100644
index 0000000000..94cd3e6ae2
--- /dev/null
+++ b/testing/web-platform/tests/webmessaging/with-ports/017.html
@@ -0,0 +1,18 @@
+<!doctype html>
+<title>origin of the script that invoked the method, about:blank</title>
+<script src="/resources/testharness.js"></script>
+<script src="/resources/testharnessreport.js"></script>
+<iframe src="about:blank"></iframe>
+<div id=log></div>
+<script>
+async_test(function() {
+  window[0].postMessage('', '*', []);
+  window[0].onmessage = this.step_func(function(e) {
+    assert_equals(e.origin, location.protocol + '//' + location.host);
+    assert_array_equals(e.ports, []);
+    this.done();
+  });
+});
+</script>
+
+
diff --git a/testing/web-platform/tests/webmessaging/with-ports/018.html b/testing/web-platform/tests/webmessaging/with-ports/018.html
new file mode 100644
index 0000000000..5525206e44
--- /dev/null
+++ b/testing/web-platform/tests/webmessaging/with-ports/018.html
@@ -0,0 +1,18 @@
+<!doctype html>
+<title>origin of the script that invoked the method, javascript:</title>
+<script src="/resources/testharness.js"></script>
+<script src="/resources/testharnessreport.js"></script>
+<iframe src="javascript:''"></iframe>
+<div id=log></div>
+<script>
+async_test(function() {
+  window[0].postMessage('', '*', []);
+  window[0].onmessage = this.step_func(function(e) {
+    assert_equals(e.origin, location.protocol + '//' + location.host);
+    assert_array_equals(e.ports, []);
+    this.done();
+  });
+});
+</script>
+
+
diff --git a/testing/web-platform/tests/webmessaging/with-ports/019.html b/testing/web-platform/tests/webmessaging/with-ports/019.html
new file mode 100644
index 0000000000..e9de6c36e1
--- /dev/null
+++ b/testing/web-platform/tests/webmessaging/with-ports/019.html
@@ -0,0 +1,20 @@
+<!doctype html>
+<title>origin of the script that invoked the method, scheme/host/port</title>
+<script src="/resources/testharness.js"></script>
+<script src="/resources/testharnessreport.js"></script>
+<iframe src="../without-ports/019-1.html"></iframe>
+<div id=log></div>
+<script>
+async_test(function(test) {
+  onload = test.step_func(function() {
+    window[0].postMessage('', location.protocol.toUpperCase() + '//' + location.host.toUpperCase() + '/', []);
+    window[0].onmessage = test.step_func(function(e) {
+      assert_equals(e.origin, location.protocol + '//' + location.host);
+      assert_array_equals(e.ports, []);
+      test.done();
+    });
+  });
+});
+</script>
+
+
diff --git a/testing/web-platform/tests/webmessaging/with-ports/020.html b/testing/web-platform/tests/webmessaging/with-ports/020.html
new file mode 100644
index 0000000000..426a3d2700
--- /dev/null
+++ b/testing/web-platform/tests/webmessaging/with-ports/020.html
@@ -0,0 +1,32 @@
+<!doctype html>
+<title>cross-origin test</title>
+<script src="/resources/testharness.js"></script>
+<script src="/resources/testharnessreport.js"></script>
+<iframe src="../without-ports/020-1.html"></iframe>
+<div id="log"></div>
+<script>
+setup({ single_test: true });
+
+var iframe = document.createElement('iframe');
+var url_prefix = location.href.replace('://', '://www1.').replace(/\/with(out)?-ports\/[^\/]+$/, '');
+var url = url_prefix + '/without-ports/020-1.html';
+iframe.src = url;
+document.body.appendChild(iframe);
+</script>
+<div id=log></div>
+<script>
+onload = function() {
+  window[0].postMessage(1, location.href, []);
+  window[1].postMessage(2, url, []);
+  var i = 0;
+  onmessage = function(e) {
+    i++;
+    assert_equals(e.data[0], i);
+    assert_equals(e.data[1], location.protocol + '//' + location.host);
+    if (i === 2) {
+      done();
+    }
+  };
+};
+</script>
+
diff --git a/testing/web-platform/tests/webmessaging/with-ports/021.html b/testing/web-platform/tests/webmessaging/with-ports/021.html
new file mode 100644
index 0000000000..2801d45a44
--- /dev/null
+++ b/testing/web-platform/tests/webmessaging/with-ports/021.html
@@ -0,0 +1,32 @@
+<!doctype html>
+<title>cross-origin test</title>
+<script src="/resources/testharness.js"></script>
+<script src="/resources/testharnessreport.js"></script>
+<iframe src="../without-ports/020-1.html"></iframe>
+<div id="log"></div>
+<script>
+setup({ single_test: true });
+
+var iframe = document.createElement('iframe');
+var url_prefix = location.href.replace('://', '://www1.').replace(/\/with(out)?-ports\/[^\/]+$/, '');
+var url = url_prefix + '/without-ports/020-1.html';
+iframe.src = url;
+document.body.appendChild(iframe);
+</script>
+<div id=log></div>
+<script>
+onload = function() {
+  window[0].postMessage(1, '*', []);
+  window[1].postMessage(2, '*', []);
+  var i = 0;
+  onmessage = function(e) {
+    i++;
+    assert_equals(e.data[0], i);
+    assert_equals(e.data[1], location.protocol + '//' + location.host);
+    if (i === 2) {
+      done();
+    }
+  };
+};
+</script>
+
diff --git a/testing/web-platform/tests/webmessaging/with-ports/023.html b/testing/web-platform/tests/webmessaging/with-ports/023.html
new file mode 100644
index 0000000000..e2569a8463
--- /dev/null
+++ b/testing/web-platform/tests/webmessaging/with-ports/023.html
@@ -0,0 +1,11 @@
+<!doctype html>
+<title>null ports</title>
+<script src="/resources/testharness.js"></script>
+<script src="/resources/testharnessreport.js"></script>
+<div id=log></div>
+<script>
+test(function(t) {
+  assert_throws_js(TypeError, () => postMessage('', '*', null));
+});
+</script>
+
diff --git a/testing/web-platform/tests/webmessaging/with-ports/024.html b/testing/web-platform/tests/webmessaging/with-ports/024.html
new file mode 100644
index 0000000000..e6c0dcba08
--- /dev/null
+++ b/testing/web-platform/tests/webmessaging/with-ports/024.html
@@ -0,0 +1,15 @@
+<!doctype html>
+<title>undefined as ports</title>
+<script src="/resources/testharness.js"></script>
+<script src="/resources/testharnessreport.js"></script>
+<div id=log></div>
+<script>
+async_test(function() {
+  postMessage('', '*', undefined);
+  onmessage = this.step_func(function(e) {
+    assert_array_equals(e.ports, []);
+    this.done();
+  });
+});
+</script>
+
diff --git a/testing/web-platform/tests/webmessaging/with-ports/025.html b/testing/web-platform/tests/webmessaging/with-ports/025.html
new file mode 100644
index 0000000000..7af2a852ed
--- /dev/null
+++ b/testing/web-platform/tests/webmessaging/with-ports/025.html
@@ -0,0 +1,13 @@
+<!doctype html>
+<title>1 as ports</title>
+<script src="/resources/testharness.js"></script>
+<script src="/resources/testharnessreport.js"></script>
+<div id=log></div>
+<script>
+test(function() {
+   assert_throws_js(TypeError, function() {
+      postMessage('', '*', 1);
+   });
+});
+</script>
+
diff --git a/testing/web-platform/tests/webmessaging/with-ports/026.html b/testing/web-platform/tests/webmessaging/with-ports/026.html
new file mode 100644
index 0000000000..2af90e6be3
--- /dev/null
+++ b/testing/web-platform/tests/webmessaging/with-ports/026.html
@@ -0,0 +1,13 @@
+<!doctype html>
+<title>object with length as transferable</title>
+<script src="/resources/testharness.js"></script>
+<script src="/resources/testharnessreport.js"></script>
+<div id=log></div>
+<script>
+test(function() {
+   assert_throws_js(TypeError, function() {
+      postMessage('', '*', {length:1});
+   });
+});
+</script>
+
diff --git a/testing/web-platform/tests/webmessaging/with-ports/027.html b/testing/web-platform/tests/webmessaging/with-ports/027.html
new file mode 100644
index 0000000000..7158351258
--- /dev/null
+++ b/testing/web-platform/tests/webmessaging/with-ports/027.html
@@ -0,0 +1,26 @@
+<!doctype html>
+<title>message channel as ports</title>
+<script src="/resources/testharness.js"></script>
+<script src="/resources/testharnessreport.js"></script>
+<div id=log></div>
+<script>
+async_test(function(t) {
+  var channel = new MessageChannel();
+  postMessage('', '*', [channel.port1, channel.port2]);
+  onmessage = t.step_func(function(e) {
+    assert_equals(e.ports.length, 2);
+    t.done();
+  });
+}, "MessageChannel's ports as MessagePort objects");
+
+test(() => {
+  var channel = new MessageChannel();
+  channel[0] = channel.port1;
+  channel[1] = channel.port2;
+  channel.length = 2;
+  assert_throws_js(TypeError,
+                   () => { postMessage('', '*', channel) },
+                   'Old-style WebIDL arrays must throw a type error');
+}, "Old-style array objects");
+</script>
+
diff --git a/testing/web-platform/tests/webmessaging/without-ports/001.html b/testing/web-platform/tests/webmessaging/without-ports/001.html
new file mode 100644
index 0000000000..09c28c5a5c
--- /dev/null
+++ b/testing/web-platform/tests/webmessaging/without-ports/001.html
@@ -0,0 +1,12 @@
+<!doctype html>
+<title>resolving broken url</title>
+<script src="/resources/testharness.js"></script>
+<script src="/resources/testharnessreport.js"></script>
+<div id="log"></div>
+<script>
+test(function() {
+  assert_throws_dom('SYNTAX_ERR', function() {
+    postMessage('', 'http://foo bar');
+  }, 'should have failed to resolve');
+});
+</script>
diff --git a/testing/web-platform/tests/webmessaging/without-ports/002.html b/testing/web-platform/tests/webmessaging/without-ports/002.html
new file mode 100644
index 0000000000..ef3eceb2a0
--- /dev/null
+++ b/testing/web-platform/tests/webmessaging/without-ports/002.html
@@ -0,0 +1,14 @@
+<!doctype html>
+<title>resolving url with stuff in host-specific</title>
+<script src="/resources/testharness.js"></script>
+<script src="/resources/testharnessreport.js"></script>
+<div id="log"></div>
+<script>
+async_test(function() {
+  postMessage('', location.protocol + '//' + location.host + '//');
+  onmessage = this.step_func(function(e) {
+    assert_equals(e.origin, location.protocol + '//' + location.host);
+    this.done();
+  });
+});
+</script>
diff --git a/testing/web-platform/tests/webmessaging/without-ports/003.html b/testing/web-platform/tests/webmessaging/without-ports/003.html
new file mode 100644
index 0000000000..6dc1e55777
--- /dev/null
+++ b/testing/web-platform/tests/webmessaging/without-ports/003.html
@@ -0,0 +1,12 @@
+<!doctype html>
+<title>resolving 'example.org'</title>
+<script src="/resources/testharness.js"></script>
+<script src="/resources/testharnessreport.js"></script>
+<div id="log"></div>
+<script>
+test(function() {
+  assert_throws_dom('SYNTAX_ERR', function() {
+    postMessage('', 'example.org');
+  }, 'targetOrigin is not an absolute url');
+});
+</script>
diff --git a/testing/web-platform/tests/webmessaging/without-ports/004.html b/testing/web-platform/tests/webmessaging/without-ports/004.html
new file mode 100644
index 0000000000..9a9eb81a5d
--- /dev/null
+++ b/testing/web-platform/tests/webmessaging/without-ports/004.html
@@ -0,0 +1,14 @@
+<!doctype html>
+<title>special value '/'</title>
+<script src="/resources/testharness.js"></script>
+<script src="/resources/testharnessreport.js"></script>
+<div id="log"></div>
+<script>
+async_test(function() {
+  postMessage('', '/');
+  onmessage = this.step_func(function(e) {
+    assert_equals(e.data, '');
+    this.done();
+  });
+});
+</script>
diff --git a/testing/web-platform/tests/webmessaging/without-ports/005.html b/testing/web-platform/tests/webmessaging/without-ports/005.html
new file mode 100644
index 0000000000..ed05a476bc
--- /dev/null
+++ b/testing/web-platform/tests/webmessaging/without-ports/005.html
@@ -0,0 +1,14 @@
+<!doctype html>
+<title>resolving a same origin targetOrigin</title>
+<script src="/resources/testharness.js"></script>
+<script src="/resources/testharnessreport.js"></script>
+<div id="log"></div>
+<script>
+async_test(function() {
+  postMessage('', location.protocol + '//' + location.host);
+  onmessage = this.step_func(function(e) {
+    assert_equals(e.data, '');
+    this.done();
+  });
+});
+</script>
diff --git a/testing/web-platform/tests/webmessaging/without-ports/006.html b/testing/web-platform/tests/webmessaging/without-ports/006.html
new file mode 100644
index 0000000000..47479ea011
--- /dev/null
+++ b/testing/web-platform/tests/webmessaging/without-ports/006.html
@@ -0,0 +1,14 @@
+<!doctype html>
+<title>resolving a same origin targetOrigin with trailing slash</title>
+<script src="/resources/testharness.js"></script>
+<script src="/resources/testharnessreport.js"></script>
+<div id="log"></div>
+<script>
+async_test(function() {
+  postMessage('', location.protocol + '//' + location.host + '/');
+  onmessage = this.step_func(function(e) {
+    assert_equals(e.data, '');
+    this.done();
+  });
+});
+</script>
diff --git a/testing/web-platform/tests/webmessaging/without-ports/007.html b/testing/web-platform/tests/webmessaging/without-ports/007.html
new file mode 100644
index 0000000000..eb2b5c52e5
--- /dev/null
+++ b/testing/web-platform/tests/webmessaging/without-ports/007.html
@@ -0,0 +1,14 @@
+<!doctype html>
+<title>targetOrigin '*'</title>
+<script src="/resources/testharness.js"></script>
+<script src="/resources/testharnessreport.js"></script>
+<div id="log"></div>
+<script>
+async_test(function() {
+  postMessage('', '*');
+  onmessage = this.step_func(function(e) {
+    assert_equals(e.data, '');
+    this.done();
+  });
+});
+</script>
diff --git a/testing/web-platform/tests/webmessaging/without-ports/009.html b/testing/web-platform/tests/webmessaging/without-ports/009.html
new file mode 100644
index 0000000000..d613b4a073
--- /dev/null
+++ b/testing/web-platform/tests/webmessaging/without-ports/009.html
@@ -0,0 +1,12 @@
+<!doctype html>
+<title>zero arguments</title>
+<script src="/resources/testharness.js"></script>
+<script src="/resources/testharnessreport.js"></script>
+<div id="log"></div>
+<script>
+test(function() {
+  assert_throws_js(TypeError, function() {
+    postMessage();
+  });
+});
+</script>
diff --git a/testing/web-platform/tests/webmessaging/without-ports/010.html b/testing/web-platform/tests/webmessaging/without-ports/010.html
new file mode 100644
index 0000000000..062316f680
--- /dev/null
+++ b/testing/web-platform/tests/webmessaging/without-ports/010.html
@@ -0,0 +1,112 @@
+<!doctype html>
+<title>message clone</title>
+<script src="/resources/testharness.js"></script>
+<script src="/resources/testharnessreport.js"></script>
+<script src="../support/compare.js"></script>
+<div id=log></div>
+<script>
+  var err = new Error('foo');
+  var date = new Date();
+
+  var test_array = [ undefined,
+                     null,
+                     false,
+                     true,
+                     1,
+                     NaN,
+                     Infinity,
+                     'foo',
+                     date,
+                     /foo/,
+                     null/*self*/,
+                     null/*err*/];
+
+  var cloned_array = [ undefined,
+                       null,
+                       false,
+                       true,
+                       1,
+                       NaN,
+                       Infinity,
+                       'foo',
+                       date,
+                       /foo/,
+                       null/*self*/,
+                       null/*err*/];
+
+  var test_object = {a: undefined,
+                     b: null,
+                     c: false,
+                     d: true,
+                     e: 1,
+                     f: NaN,
+                     g: Infinity,
+                     h: 'foo',
+                     i: date,
+                     j: /foo/,
+                     k: null/*self*/,
+                     l: [],
+                     m: {},
+                     n: null /*err*/};
+
+  var cloned_object = {a:undefined, b:null, c:false, d:true, e:1, f:NaN, g:Infinity, h:'foo', i: date, j: /foo/,  k:null, l: [], m: {}, n:null};
+
+  var tests = [undefined, null,
+               false, true,
+               1, NaN, Infinity,
+               'foo',
+               date,
+               /foo/,
+               /* ImageData, File, FileData, FileList, */
+               null /*self*/,
+               test_array,
+               test_object,
+               null /*err*/];
+
+  for (var i = 0; i < tests.length; ++i) {
+    postMessage(tests[i], '*');
+  }
+
+  var test_undefined = async_test('undefined');
+  var test_null = async_test('null');
+  var test_false = async_test('false');
+  var test_true = async_test('true');
+  var test_1 = async_test('1');
+  var test_NaN = async_test('NaN');
+  var test_Infinity = async_test('Infinity');
+  var test_string = async_test('string');
+  var test_date = async_test('date');
+  var test_regex = async_test('regex');
+  var test_self = async_test('self');
+  var test_array = async_test('array');
+  var test_object = async_test('object');
+  var test_error = async_test('error');
+  var test_unreached = async_test('unreached');
+
+  var j = 0;
+  onmessage = function(e) {
+    switch (j) {
+      case 0: test_undefined.step(function() { assert_equals(e.data, undefined); this.done(); }); break;
+      case 1: test_null.step(function() { assert_equals(e.data, null); this.done(); }); break;
+      case 2: test_false.step(function() { assert_false(e.data); this.done(); }); break;
+      case 3: test_true.step(function() { assert_true(e.data); this.done(); }); break;
+      case 4: test_1.step(function() { assert_equals(e.data, 1); this.done(); }); break;
+      case 5: test_NaN.step(function() { assert_equals(e.data, NaN); this.done(); }); break;
+      case 6: test_Infinity.step(function() { assert_equals(e.data, Infinity); this.done(); }); break;
+      case 7: test_string.step(function() { assert_equals(e.data, 'foo'); this.done(); }); break;
+      case 8: test_date.step(function() { assert_true(sameDate(e.data, date)); this.done(); }); break;
+      case 9: test_regex.step(function() { assert_equals('' + e.data, '/foo/'); assert_equals(e.data instanceof RegExp, true, 'e.data instanceof RegExp'); this.done(); }); break;
+      // not testing it any more, as cloning host objects will now raise exceptions. TODO: add (exceptional) tests for these.
+      case 10: test_self.step(function() { assert_equals(e.data, null); this.done(); }); break;
+      case 11: test_array.step(function() { assert_array_equals_(e.data, cloned_array, 'array'); this.done(); }); break;
+      case 12: test_object.step(function() { assert_object_equals_(e.data, cloned_object, 'object'); this.done(); }); break;
+      case 13:
+        test_error.step(function() { assert_equals(e.data, null, 'new Error()'); this.done(); });
+        setTimeout(test_unreached.step_func(function() { assert_equals(j, 14); this.done(); }), 50);
+        break;
+      default: test_unreached.step(function() { assert_unreached('got an unexpected message event ('+j+')'); });
+    };
+    j++;
+  }
+
+</script>
diff --git a/testing/web-platform/tests/webmessaging/without-ports/011.html b/testing/web-platform/tests/webmessaging/without-ports/011.html
new file mode 100644
index 0000000000..cac2990c49
--- /dev/null
+++ b/testing/web-platform/tests/webmessaging/without-ports/011.html
@@ -0,0 +1,29 @@
+<!doctype html>
+<title>posting an imagedata (from a cloned canvas) in an array</title>
+<script src="/resources/testharness.js"></script>
+<script src="/resources/testharnessreport.js"></script>
+<div id="log"></div>
+<script>
+async_test(function() {
+
+  var canvas = document.createElement('canvas');
+  var clone = canvas.cloneNode(true);
+  var ctx = clone.getContext('2d');
+  var imagedata = ctx.getImageData(0, 0, 300, 150);
+  postMessage([imagedata], '*');
+
+  onmessage = this.step_func(function(e) {
+    function processPixels(imagedata) {
+      var pixeldata = imagedata.data;
+      for (var i = 0; i < pixeldata.length; i = i+4) {
+        pixeldata[i] = 128;
+        assert_equals(pixeldata[i], 128);
+      }
+    }
+    processPixels(e.data[0]);
+    this.done();
+  });
+
+});
+</script>
+
diff --git a/testing/web-platform/tests/webmessaging/without-ports/012.html b/testing/web-platform/tests/webmessaging/without-ports/012.html
new file mode 100644
index 0000000000..8eb46539b7
--- /dev/null
+++ b/testing/web-platform/tests/webmessaging/without-ports/012.html
@@ -0,0 +1,16 @@
+<!doctype html>
+<title>loop in array in structured clone</title>
+<script src="/resources/testharness.js"></script>
+<script src="/resources/testharnessreport.js"></script>
+<div id=log></div>
+<script>
+async_test(function() {
+  var x = [];
+  x[0] = x;
+  postMessage(x, '*');
+  onmessage = this.step_func(function(e) {
+    assert_equals(e.data, e.data[0]);
+    this.done();
+  });
+});
+</script>
diff --git a/testing/web-platform/tests/webmessaging/without-ports/013.html b/testing/web-platform/tests/webmessaging/without-ports/013.html
new file mode 100644
index 0000000000..34ba76221a
--- /dev/null
+++ b/testing/web-platform/tests/webmessaging/without-ports/013.html
@@ -0,0 +1,17 @@
+<!doctype html>
+<title>loop in object in structured clone</title>
+<script src="/resources/testharness.js"></script>
+<script src="/resources/testharnessreport.js"></script>
+<div id="log"></div>
+<script>
+async_test(function() {
+  var x = {};
+  x.foo = x;
+  postMessage(x, '*');
+  onmessage = this.step_func(function(e) {
+    assert_equals(e.data, e.data.foo);
+    this.done();
+  });
+});
+</script>
+
diff --git a/testing/web-platform/tests/webmessaging/without-ports/014.html b/testing/web-platform/tests/webmessaging/without-ports/014.html
new file mode 100644
index 0000000000..f200aa4673
--- /dev/null
+++ b/testing/web-platform/tests/webmessaging/without-ports/014.html
@@ -0,0 +1,17 @@
+<!doctype html>
+<title>structured clone vs reference</title>
+<script src="/resources/testharness.js"></script>
+<script src="/resources/testharnessreport.js"></script>
+<div id="log"></div>
+<script>
+async_test(function(t) {
+  var x = [];
+  y = [x,x];
+  postMessage(y, '*');
+  onmessage = t.step_func(function(e) {
+    assert_equals(e.data[0], e.data[1], 'e.data[0] === e.data[1]');
+    assert_not_equals(e.data[0], x, 'e.data[0] !== x');
+    t.done();
+  });
+});
+</script>
diff --git a/testing/web-platform/tests/webmessaging/without-ports/015.html b/testing/web-platform/tests/webmessaging/without-ports/015.html
new file mode 100644
index 0000000000..a17c97be19
--- /dev/null
+++ b/testing/web-platform/tests/webmessaging/without-ports/015.html
@@ -0,0 +1,15 @@
+<!doctype html>
+<title>different origin</title>
+<script src="/resources/testharness.js"></script>
+<script src="/resources/testharnessreport.js"></script>
+<div id=log></div>
+<script>
+async_test(function() {
+  postMessage('', 'http://example.org', []);
+  onmessage = this.step_func(function(e) {
+    assert_unreached();
+  });
+  setTimeout(this.step_func(function(){ this.done(); }), 50);
+});
+</script>
+
diff --git a/testing/web-platform/tests/webmessaging/without-ports/016.html b/testing/web-platform/tests/webmessaging/without-ports/016.html
new file mode 100644
index 0000000000..51cadec7c1
--- /dev/null
+++ b/testing/web-platform/tests/webmessaging/without-ports/016.html
@@ -0,0 +1,23 @@
+<!doctype html>
+<title>origin of the script that invoked the method, data:</title>
+<script src="/resources/testharness.js"></script>
+<script src="/resources/testharnessreport.js"></script>
+<iframe src="data:text/html,<script>onmessage = function(e) { parent.postMessage(e.origin, '*'); }; parent.postMessage('loaded', '*');</script>"></iframe>
+<div id=log></div>
+<script>
+async_test(function() {
+  onmessage = this.step_func(function(e) {
+    if (e.data === 'loaded') {
+      window[0].postMessage('', '*');
+      return;
+    }
+
+    assert_equals(e.data, location.protocol + '//' + location.host);
+    assert_equals(e.origin, 'null');
+    assert_array_equals(e.ports, []);
+    this.done();
+  });
+});
+</script>
+
+
diff --git a/testing/web-platform/tests/webmessaging/without-ports/017.html b/testing/web-platform/tests/webmessaging/without-ports/017.html
new file mode 100644
index 0000000000..a4a0483624
--- /dev/null
+++ b/testing/web-platform/tests/webmessaging/without-ports/017.html
@@ -0,0 +1,18 @@
+<!doctype html>
+<title>origin of the script that invoked the method, about:blank</title>
+<script src="/resources/testharness.js"></script>
+<script src="/resources/testharnessreport.js"></script>
+<iframe src="about:blank"></iframe>
+<div id=log></div>
+<script>
+async_test(function() {
+  window[0].postMessage('', '*');
+  window[0].onmessage = this.step_func(function(e) {
+    assert_equals(e.origin, location.protocol + '//' + location.host);
+    assert_array_equals(e.ports, []);
+    this.done();
+  });
+});
+</script>
+
+
diff --git a/testing/web-platform/tests/webmessaging/without-ports/018.html b/testing/web-platform/tests/webmessaging/without-ports/018.html
new file mode 100644
index 0000000000..207ae36ed8
--- /dev/null
+++ b/testing/web-platform/tests/webmessaging/without-ports/018.html
@@ -0,0 +1,17 @@
+<!doctype html>
+<title>origin of the script that invoked the method, javascript:</title>
+<script src="/resources/testharness.js"></script>
+<script src="/resources/testharnessreport.js"></script>
+<iframe src="javascript:''"></iframe>
+<div id=log></div>
+<script>
+async_test(function() {
+  window[0].postMessage('', '*');
+  window[0].onmessage = this.step_func(function(e) {
+    assert_equals(e.origin, location.protocol + '//' + location.host);
+    this.done();
+  });
+});
+</script>
+
+
diff --git a/testing/web-platform/tests/webmessaging/without-ports/019-1.html b/testing/web-platform/tests/webmessaging/without-ports/019-1.html
new file mode 100644
index 0000000000..513123ee6d
--- /dev/null
+++ b/testing/web-platform/tests/webmessaging/without-ports/019-1.html
@@ -0,0 +1 @@
+<!-- blank -->
\ No newline at end of file
diff --git a/testing/web-platform/tests/webmessaging/without-ports/019.html b/testing/web-platform/tests/webmessaging/without-ports/019.html
new file mode 100644
index 0000000000..38e7ca230e
--- /dev/null
+++ b/testing/web-platform/tests/webmessaging/without-ports/019.html
@@ -0,0 +1,20 @@
+<!doctype html>
+<title>origin of the script that invoked the method, scheme/host/port</title>
+<script src="/resources/testharness.js"></script>
+<script src="/resources/testharnessreport.js"></script>
+<iframe src="../without-ports/019-1.html"></iframe>
+<div id=log></div>
+<script>
+async_test(function(test) {
+  onload = test.step_func(function() {
+    window[0].postMessage('', location.protocol.toUpperCase() + '//' + location.host.toUpperCase() + '/');
+    window[0].onmessage = test.step_func(function(e) {
+      assert_equals(e.origin, location.protocol + '//' + location.host);
+      assert_array_equals(e.ports, []);
+      test.done();
+    });
+  });
+});
+</script>
+
+
diff --git a/testing/web-platform/tests/webmessaging/without-ports/020-1.html b/testing/web-platform/tests/webmessaging/without-ports/020-1.html
new file mode 100644
index 0000000000..225bd7a41e
--- /dev/null
+++ b/testing/web-platform/tests/webmessaging/without-ports/020-1.html
@@ -0,0 +1,5 @@
+<script>
+onmessage = function(e) {
+  parent.postMessage([e.data, e.origin], '*');
+}
+</script>
\ No newline at end of file
diff --git a/testing/web-platform/tests/webmessaging/without-ports/020.html b/testing/web-platform/tests/webmessaging/without-ports/020.html
new file mode 100644
index 0000000000..61bfddb901
--- /dev/null
+++ b/testing/web-platform/tests/webmessaging/without-ports/020.html
@@ -0,0 +1,32 @@
+<!doctype html>
+<title>cross-origin test</title>
+<script src="/resources/testharness.js"></script>
+<script src="/resources/testharnessreport.js"></script>
+<iframe src="../without-ports/020-1.html"></iframe>
+<div id="log"></div>
+<script>
+setup({ single_test: true });
+
+var iframe = document.createElement('iframe');
+var url_prefix = location.href.replace('://', '://www1.').replace(/\/with(out)?-ports\/[^\/]+$/, '');
+var url = url_prefix + '/without-ports/020-1.html';
+iframe.src = url;
+document.body.appendChild(iframe);
+</script>
+<div id=log></div>
+<script>
+onload = function() {
+  window[0].postMessage(1, location.href);
+  window[1].postMessage(2, url);
+  var i = 0;
+  onmessage = function(e) {
+    i++;
+    assert_equals(e.data[0], i);
+    assert_equals(e.data[1], location.protocol + '//' + location.host);
+    if (i == 2) {
+      done();
+    }
+  };
+};
+</script>
+
diff --git a/testing/web-platform/tests/webmessaging/without-ports/021.html b/testing/web-platform/tests/webmessaging/without-ports/021.html
new file mode 100644
index 0000000000..5072508d9c
--- /dev/null
+++ b/testing/web-platform/tests/webmessaging/without-ports/021.html
@@ -0,0 +1,32 @@
+<!doctype html>
+<title>cross-origin test</title>
+<script src="/resources/testharness.js"></script>
+<script src="/resources/testharnessreport.js"></script>
+<iframe src="../without-ports/020-1.html"></iframe>
+<div id="log"></div>
+<script>
+setup({ single_test: true });
+
+var iframe = document.createElement('iframe');
+var url_prefix = location.href.replace('://', '://www1.').replace(/\/with(out)?-ports\/[^\/]+$/, '');
+var url = url_prefix + '/without-ports/020-1.html';
+iframe.src = url;
+document.body.appendChild(iframe);
+</script>
+<div id=log></div>
+<script>
+onload = function() {
+  window[0].postMessage(1, '*');
+  window[1].postMessage(2, '*');
+  var i = 0;
+  onmessage = function(e) {
+    i++;
+    assert_equals(e.data[0], i);
+    assert_equals(e.data[1], location.protocol + '//' + location.host);
+    if (i === 2) {
+      done();
+    }
+  };
+};
+</script>
+
diff --git a/testing/web-platform/tests/webmessaging/without-ports/023.html b/testing/web-platform/tests/webmessaging/without-ports/023.html
new file mode 100644
index 0000000000..1e12ac4a55
--- /dev/null
+++ b/testing/web-platform/tests/webmessaging/without-ports/023.html
@@ -0,0 +1,29 @@
+<!doctype html>
+<title>Object cloning: own properties only, don't follow prototype</title>
+<script src="/resources/testharness.js"></script>
+<script src="/resources/testharnessreport.js"></script>
+<div id="log"></div>
+<script>
+var Parent = function(){
+  this.c = "xyz";
+};
+
+var Child = function(a, b) {
+  this.a = a;
+  this.b = b;
+};
+Child.prototype = new Parent;
+
+async_test(function() {
+  var obj = new Child(1, 2);
+  var ch = new MessageChannel();
+  ch.port1.onmessage = this.step_func(function(e) {
+    for (var i in e.data.obj)
+      assert_not_equals(i, 'c');
+    this.done();
+   });
+  ch.port2.start();
+  ch.port2.postMessage({obj: obj});
+});
+
+</script>
diff --git a/testing/web-platform/tests/webmessaging/without-ports/024.html b/testing/web-platform/tests/webmessaging/without-ports/024.html
new file mode 100644
index 0000000000..0e4651593a
--- /dev/null
+++ b/testing/web-platform/tests/webmessaging/without-ports/024.html
@@ -0,0 +1,14 @@
+<!doctype html>
+<title>Object cloning: throw an exception if function values encountered</title>
+<script src="/resources/testharness.js"></script>
+<script src="/resources/testharnessreport.js"></script>
+<div id=log></div>
+<script>
+test(function() {
+  var obj = { f : function(){}};
+  var ch = new MessageChannel();
+  ch.port1.onmessage = function(){};
+  ch.port2.start();
+  assert_throws_dom('DATA_CLONE_ERR', function() { ch.port2.postMessage({obj: obj}); });
+});
+</script>
diff --git a/testing/web-platform/tests/webmessaging/without-ports/025-1.js b/testing/web-platform/tests/webmessaging/without-ports/025-1.js
new file mode 100644
index 0000000000..bd1d778d9b
--- /dev/null
+++ b/testing/web-platform/tests/webmessaging/without-ports/025-1.js
@@ -0,0 +1,15 @@
+importScripts("/resources/testharness.js");
+
+test(function() {
+  var ch = new MessageChannel();
+  assert_true(ch.port1 instanceof MessagePort,
+              "Worker MessageChannel's port not an instance of MessagePort");
+}, "Worker MessageChannel's port should be an instance of MessagePort");
+
+test(function() {
+  assert_throws_js(TypeError, function() {
+    new MessagePort()
+  }, "MessagePort is [[Callable]]");
+}, "Worker MessagePort should not be [[Callable]]");
+
+done();
diff --git a/testing/web-platform/tests/webmessaging/without-ports/025.html b/testing/web-platform/tests/webmessaging/without-ports/025.html
new file mode 100644
index 0000000000..4686febe94
--- /dev/null
+++ b/testing/web-platform/tests/webmessaging/without-ports/025.html
@@ -0,0 +1,13 @@
+<!doctype html>
+<title>MessagePort constructor properties</title>
+<script src="/resources/testharness.js"></script>
+<script src="/resources/testharnessreport.js"></script>
+<div id=log></div>
+<script>
+test(function() {
+   var ch = new MessageChannel();
+   assert_true(ch.port1 instanceof MessagePort, "MessageChannel's port not an instance of MessagePort");
+   assert_throws_js(TypeError, function () { var p = new MessagePort();}, "MessagePort is [[Callable]]");
+});
+fetch_tests_from_worker(new Worker("025-1.js"));
+</script>
diff --git a/testing/web-platform/tests/webmessaging/without-ports/026.html b/testing/web-platform/tests/webmessaging/without-ports/026.html
new file mode 100644
index 0000000000..546da8a91b
--- /dev/null
+++ b/testing/web-platform/tests/webmessaging/without-ports/026.html
@@ -0,0 +1,17 @@
+<!doctype html>
+<title>Cloning objects with getter properties</title>
+<script src="/resources/testharness.js"></script>
+<script src="/resources/testharnessreport.js"></script>
+<div id=log></div>
+<script>
+async_test(function() {
+   var obj = {};
+   var err = new Error("getter_should_propagate_exceptions");
+   obj.__defineGetter__( "field", function(){ throw err });
+
+   assert_throws_exactly(err, function() {
+     postMessage(obj, '*');
+  });
+  this.done();
+});
+</script>
diff --git a/testing/web-platform/tests/webmessaging/without-ports/027.html b/testing/web-platform/tests/webmessaging/without-ports/027.html
new file mode 100644
index 0000000000..36aa9446a5
--- /dev/null
+++ b/testing/web-platform/tests/webmessaging/without-ports/027.html
@@ -0,0 +1,19 @@
+<!doctype html>
+<title>Cloning objects, preserving sharing</title>
+<script src="/resources/testharness.js"></script>
+<script src="/resources/testharnessreport.js"></script>
+<div id=log></div>
+<script>
+async_test(function() {
+  var obj1 = {o: 1};
+  var obj2 = {d: obj1};
+  var obj3 = {d: obj1};
+  var obj_dag = {b: obj2, c: obj3};
+
+  postMessage(obj_dag, '*');
+  onmessage = this.step_func(function(e) {
+    assert_equals(e.data.b.d, e.data.c.d);
+    this.done();
+  });
+});
+</script>
diff --git a/testing/web-platform/tests/webmessaging/without-ports/028.html b/testing/web-platform/tests/webmessaging/without-ports/028.html
new file mode 100644
index 0000000000..d51ad7d3b6
--- /dev/null
+++ b/testing/web-platform/tests/webmessaging/without-ports/028.html
@@ -0,0 +1,19 @@
+<!doctype html>
+<title>Cloning objects, preserving sharing #2</title>
+<script src="/resources/testharness.js"></script>
+<script src="/resources/testharnessreport.js"></script>
+<canvas id="a" width=30 height=30></canvas>
+<div id=log></div>
+<script>
+async_test(function() {
+  var canvas = document.getElementsByTagName("canvas")[0];
+  var context = canvas.getContext("2d");
+  var img_data = context.getImageData(0, 0, 30, 30);
+  var obj = {a: img_data, b: {c: img_data, d: 3}};
+  postMessage(obj, '*');
+  onmessage = this.step_func(function(e) {
+    assert_equals(e.data.a, e.data.b.c);
+    this.done();
+  });
+});
+</script>
diff --git a/testing/web-platform/tests/webmessaging/without-ports/029.html b/testing/web-platform/tests/webmessaging/without-ports/029.html
new file mode 100644
index 0000000000..4b1b38f741
--- /dev/null
+++ b/testing/web-platform/tests/webmessaging/without-ports/029.html
@@ -0,0 +1,20 @@
+<!doctype html>
+<title>Check that getters don't linger after deletion wrt cloning</title>
+<script src="/resources/testharness.js"></script>
+<script src="/resources/testharnessreport.js"></script>
+<div id=log></div>
+<script>
+async_test(function() {
+   var obj = {};
+   obj.__defineGetter__( "a", function(){ return 2; } );
+   obj.__defineSetter__( "a", function(v){ return; } );
+   delete obj.a;
+   obj.a = 2;
+
+   postMessage(obj, '*');
+   onmessage = this.step_func(function(e) {
+     assert_equals(e.data.a, 2);
+     this.done();
+  });
+});
+</script>
diff --git a/testing/web-platform/tests/webmessaging/worker_postMessage_user_activation.js b/testing/web-platform/tests/webmessaging/worker_postMessage_user_activation.js
new file mode 100644
index 0000000000..e4c7eec2b7
--- /dev/null
+++ b/testing/web-platform/tests/webmessaging/worker_postMessage_user_activation.js
@@ -0,0 +1,3 @@
+"use strict";
+
+onmessage = e => postMessage(e.userActivation !== null);
diff --git a/testing/web-platform/tests/webmessaging/worker_postMessage_user_activation.tentative.html b/testing/web-platform/tests/webmessaging/worker_postMessage_user_activation.tentative.html
new file mode 100644
index 0000000000..203bb14985
--- /dev/null
+++ b/testing/web-platform/tests/webmessaging/worker_postMessage_user_activation.tentative.html
@@ -0,0 +1,19 @@
+<!DOCTYPE html>
+<title>postMessage with user activtion to a worker</title>
+<script src="/resources/testharness.js"></script>
+<script src="/resources/testharnessreport.js"></script>
+
+<script>
+"use strict";
+
+promise_test(async t => {
+  var worker = new Worker("worker_postMessage_user_activation.js");
+  let workerReply = () => new Promise((resolve, reject) => {
+    worker.addEventListener('message', e => resolve(e.data), {once: true});
+  });
+  worker.postMessage(null, {includeUserActivation: true});
+  assert_equals(await workerReply(), true);
+  worker.postMessage(null, {includeUserActivation: false});
+  assert_equals(await workerReply(), false);
+}, "Post Message from a worker");
+</script>