LayoutTests/fast/editing/paste-and-indent-microtask-crash.html

<script>
  if (window.testRunner)
    testRunner.dumpAsText();
  console.log("This test passes if it does not crash.")
  onload = () => {
    let h1 = document.createElement('h1');
    document.body.appendChild(h1);
    h1.appendChild(document.createElement('input'));
    h1.appendChild(document.createElement('div'));
    let h2 = document.createElement('h2');
    document.body.appendChild(h2);
    let h3 = document.createElement('h3');
    h2.appendChild(h3);
    document.execCommand('SelectAll');
    h3.appendChild(document.createElement('iframe'));
    queueMicrotask(() => {
      document.execCommand('Indent');
    });
    document.designMode = 'on';
    document.execCommand('Copy');
    document.execCommand('Paste');
  };
</script>