chromium/src/third_party/blink/web_tests/paint/theme/anonymous-element-border-painting.html

<input id="test" type="month">Input</input>
<script>
  if (window.eventSender) {
    testRunner.dumpAsText();
    var testElement = document.getElementById('test');
    document.addEventListener("keydown", function() {
      testElement.webkitRequestFullscreen();
    });
    eventSender.keyDown("Enter");
  }
</script>