testHighlightFirstOnOpen_withEnterOrSpaceSetAndFirstDisabled() {
    const node = dom.getElement('demoMenuButton');
    menuButton.decorate(node);
    menuButton.setSelectFirstOnEnterOrSpace(true);
    const menu = menuButton.getMenu();
    menu.getItemAt(0).setEnabled(false);

    menuButton.handleKeyEvent(new MyFakeEvent(KeyCodes.ENTER));
    assertEquals(
        'The first enabled item should be highlighted when opened ' +
            'with enter after setting selectFirstOnEnterOrSpace',
        'menuItem2', menuButton.getMenu().getHighlighted().getElement().id);
  }
Check that the appropriate item is selected when a menu is opened with the
keyboard, setSelectFirstOnEnterOrSpace is true, and the first menu item is
disabled.
@suppress {checkTypes} suppression added to enable type checking