LayoutTests/http/tests/media/resources/media-element-frame-destroyed-crash-subframe.html

<script>
  onload = async () => {
    if (window.testRunner)
      testRunner.dumpAsText();
    let embed0 = document.createElement('embed');
    embed0.src = 'empty.ts';
    document.body.appendChild(embed0);
    await new Blob().text();
    try {
      await new FontFace('a', 'url(data:)').load();
    } catch {}
    document.designMode = 'on';
    document.execCommand('SelectAll');
    document.execCommand('Bold');
    parent.postMessage('done');
  };
</script>