testRenderMenuAsSibling() {
    menuButton.setRenderMenuAsSibling(true);
    menuButton.addItem(new MenuItem('Menu item 1'));
    menuButton.addItem(new MenuItem('Menu item 2'));
    // By default the menu is rendered into the top level dom and the button
    // is rendered into whatever parent we provide.  If we don't provide a
    // parent then we aren't really testing anything, since both would be, by
    // default, rendered into the top level dom, and therefore siblings.
    menuButton.render(dom.getElement('siblingTest'));
    menuButton.setOpen(true);
    assertEquals(
        menuButton.getElement().parentNode,
        menuButton.getMenu().getElement().parentNode);
  }
Try rendering the menu as a sibling rather than as a child of the dom. This
tests the case when the button is rendered, rather than decorated.