LayoutTests/fast/css/first-letter-multicol-crash.html

<style>
  body {
    column-count: 2;
  }
  ::first-letter {
    width: 0;
  }
</style>
<script>
  if (window.testRunner)
    testRunner.dumpAsText();

  onload = () => {
    document.execCommand('SelectAll');
    document.designMode = 'on';
    document.execCommand('Indent');
  };
</script>
This test passes if it doesn't crash.