Bug 189490 [CommonNavigator] Go To->Resource won't enable
I0524 1. Open the Project Explorer in the Resource perspective 2. Create a vanilla project P 3. Create a folder F 4. Create a file resource R Open the Navigate->Go To file. "Resource..." will remain disabled.
bundles/org.eclipse.ui.navigator/src/org/eclipse/ui/navigator/CommonNavigator.java
* </p>
	 *  
	 * @return The (already created) instance of Common Viewer.
	 */
	public CommonViewer getCommonViewer() {
		return commonViewer;
	}
	/**
	 * @return The Navigator Content Service which populates this instance of
	 *         Common Navigator
	 */
	public INavigatorContentService getNavigatorContentService() {
		return getCommonViewer().getNavigatorContentService();
	}
	/**
	 * Returns an object which is an instance of the given class
	 * associated with this object. Returns <code>null</code> if
	 * no such object can be found.
	 *
	 * @param adapter the adapter class to look up
	 * @return a object castable to the given class, 
	 *    or <code>null</code> if this object does not
	 *    have an adapter for the given class
	 */
	public Object getAdapter(Class adapter) {
		if (adapter == COMMON_VIEWER_CLASS) {
			return getCommonViewer();
		} else if (adapter == INAVIGATOR_CONTENT_SERVICE) {
			return getCommonViewer().getNavigatorContentService();
		} else if (adapter == ISHOW_IN_TARGET_CLASS) {