chromium/src/third_party/blink/web_tests/fast/events/resources/menu-key-context-menu-position-frame.html

<form>
  <input id="ex1" type="reset" value="Reset">
  <input id="ex2" type="submit" value="Submit">
</form>
<script>
  document.addEventListener('contextmenu', parent.onEventInFrame, true);
</script>