() => {
  const mi = document.querySelector("#menubar-menuitem");
  assert_equals(mi.checked, false, "menuitem in menubar is not checked");
  assert_false(mi.matches(":checked"));
  mi.checked = true;
  assert_equals(mi.checked, false, "menuitem in menubar cannot be checked");
  assert_false(mi.matches(":checked"));
}, "menuitem in menubar is not checkable");

test(() => {
  const nonCheckable =
      document.querySelector("#menulist-menuitem-not-checkable");
  assert_equals(nonCheckable.checked, false,
  