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/internal/navigator/NavigatorContentService.java
* 
	 * @param anElement
	 *            An element from the tree (generally from a setSelection()
	 *            method).
	 * @return The set of content providers that may be able to provide a
	 *         parent.
	 */
	public ITreeContentProvider[] findParentContentProviders(Object anElement) {
		return extractContentProviders(findContentExtensionsWithPossibleChild(anElement));
	}
	/**
	 * <p>
	 * Return all of the content providers that are relevant for the viewer. The
	 * viewer is determined by the ID used to create the
	 * INavigatorContentService ({@link #getViewerId() }). See
	 * {@link #createCommonContentProvider() } for more information about how
	 * content providers are located for the root of the viewer. The root
	 * content providers are calculated once. If a new element is supplied, a
	 * client must call {@link #update() } prior in order to reset the calculated
	 * root providers.
	 * </p>
	 * 
	 * @param anElement
	 *            An element from the tree (generally the input of the viewer)
	 * @return The set of content providers that can provide root elements for a
	 *         viewer.
	 */
	public ITreeContentProvider[] findRootContentProviders(Object anElement) {
		if (rootContentProviders != null) {
			return rootContentProviders;