<style>
  html {
    -webkit-user-modify: read-write-plaintext-only;
  }
  * {
    float: right;
    border-image: url();
    max-inline-size: 0;
  }
  :first-child {
    content: url();
  }
  :nth-child(3)::first-letter {
    background: grey;
  }
  div {
    overflow-x: scroll;
  }
  div::-webkit-scrollbar {
    background: grey;
  }
</style>
<script>
if (window.testRunner)
    testRunner.dumpAsText();
onload = () => {
    document.body.appendChild(document.createElement('div'));
    document.body.appendChild(document.createElement('div'));
    document.body.appendChild(document.createElement('div'));
    document.execCommand('SelectAll');
    document.execCommand('InsertText', false, "This test passes if it doesn't crash");
};
</script>