chromium/third_party/blink/web_tests/external/wpt/element-timing/element-only-when-fully-active.html

<!DOCTYPE HTML>
<meta charset=utf-8>
<title>ElementTiming: element is only exposed for fully active documents.</title>
<body>
<script src="/resources/testharness.js"></script>
<script src="/resources/testharnessreport.js"></script>
<iframe src="resources/iframe-stores-entry.html" id="ifr"></iframe>
<script>
  let t = async_test('Only expose element attribute for fully active documents');
  t.step(() => {
    assert_implements(window.PerformanceElementTiming, "PerformanceElementTiming is not implemented");
  });
  window.triggerTest = t.step_func_done(elementEntry => {
    assert_not_equals(elementEntry.element, null);
    const iframe = document.getElementById('ifr');
    iframe.remove();
    assert_equals(elementEntry.element, null);
  });
</script>
</body>