1 files changed, 27 insertions, 0 deletions
diff --git a/testing/web-platform/tests/dom/events/Event-timestamp-cross-realm-getter.html b/testing/web-platform/tests/dom/events/Event-timestamp-cross-realm-getter.html
new file mode 100644
index 0000000000..45823de26b
--- /dev/null
+++ b/testing/web-platform/tests/dom/events/Event-timestamp-cross-realm-getter.html
@@ -0,0 +1,27 @@
+<!doctype html>
+<meta charset="utf-8">
+<title>event.timeStamp is initialized using event's relevant global object</title>
+<link rel="help" href="https://dom.spec.whatwg.org/#ref-for-dom-event-timestamp%E2%91%A1">
+<script src="/resources/testharness.js"></script>
+<script src="/resources/testharnessreport.js"></script>
+
+<body>
+<script>
+const t = async_test();
+t.step_timeout(() => {
+  const iframeDelayed = document.createElement("iframe");
+  iframeDelayed.onload = t.step_func_done(() => {
+    // Use eval() to eliminate false-positive test result for WebKit builds before r280256,
+    // which invoked WebIDL accessors in context of lexical (caller) global object.
+    const timeStampExpected = iframeDelayed.contentWindow.eval(`new Event("foo").timeStamp`);
+    const eventDelayed = new iframeDelayed.contentWindow.Event("foo");
+
+    const {get} = Object.getOwnPropertyDescriptor(Event.prototype, "timeStamp");
+    assert_approx_equals(get.call(eventDelayed), timeStampExpected, 5, "via Object.getOwnPropertyDescriptor");
+
+    Object.setPrototypeOf(eventDelayed, Event.prototype);
+    assert_approx_equals(eventDelayed.timeStamp, timeStampExpected, 5, "via Object.setPrototypeOf");
+  });
+  document.body.append(iframeDelayed);
+}, 1000);
+</script>