update-dom-during-undoing-in-textarea.html

<!doctype html>
<html>
<head>
<meta charset="utf-8">
<title>Test for updating the DOM tree while execCommand("undo") is running in the textarea</title>
<script>
"use strict";

let count = 0;
addEventListener("load", () => {
  document.execCommand("insertText", false, "F");
  document.execCommand("undo");
});

function onInputOfTextarea() {
  if (count) {
    document.querySelector("base").appendChild(
      document.querySelector("content")
    );
  }
  count++;
}
</script>
</head>
<body>
<iframe></iframe>
<textarea autofocus oninput="onInputOfTextarea()">a</textarea>
<base></base>
<content>
<menu>
</body>
</html>

chromium/third_party/blink/web_tests/external/wpt/editing/crashtests/update-dom-during-undoing-in-textarea.html