fullscreen/api/element-request-fullscreen-dialog.html

<!DOCTYPE html>
<title>Element#requestFullscreen() for dialog element</title>
<script src="/resources/testharness.js"></script>
<script src="/resources/testharnessreport.js"></script>
<script src="/resources/testdriver.js"></script>
<script src="/resources/testdriver-vendor.js"></script>
<div id="log"></div>
<dialog></dialog>
<script>
async_test(t => {
  var dialog = document.querySelector("dialog");
  assert_true(dialog instanceof HTMLDialogElement);
  document.onfullscreenchange = t.unreached_func("fullscreenchange event");
  document.onfullscreenerror = t.step_func_done();

  test_driver.bless("Initiate fullscreen", () => dialog.requestFullscreen().catch(() => {}));
});
</script>