com.gootle.gwt.user.client.Element is deprecated.
Note from Javadoc:

• As of GWT 2.6, users should use {@link com.google.gwt.dom.client.Element}
• instead. As an exception, some methods still return a <code>Element</code>
• object for backwards compatibility (though this will change in a future
• release), so overriding them will require returning an <code>Element</code>
• object too.