<html class="reftest-wait">
<script>
var eventCount = 0;
document.addEventListener("DOMContentLoaded", () => {
  const dialog = document.querySelector("dialog");
  const object = document.createElement("object");
  object.addEventListener("DOMSubtreeModified", () => {
    dialog.show();
    dialog.focus();
    document.execCommand("selectAll");
    dialog.close();
    setTimeout(() => {
      document.execCommand("selectAll");
      document.execCommand("strikeThrough");
      document.execCommand("indent");
      document.execCommand("outdent");
      eventCount--;
      if (!eventCount) {
        document.documentElement.removeAttribute("class");
      }
    });
    eventCount++;
  });
  object.setAttribute("role", "x"); // Run DOMSubtreeModified
  object.setAttribute("role", "y"); // Run DOMSubtreeModified
  document.execCommand("forwardDelete");
  document.execCommand("justifyRight");
})
</script>
<dialog id="a" contenteditable="true">a</dialog>
</html>