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
* 
	 * @see org.eclipse.ui.internal.navigator.INavigatorContentService#update()
	 */
	public void update() {
		rootContentProviders = null;
		if (structuredViewerManager != null) {
			structuredViewerManager.safeRefresh();
		}
	}
	/*
	 * (non-Javadoc)
	 * 
	 * @see
	 * org.eclipse.ui.internal.navigator.INavigatorContentService#getViewerId()
	 */
	public final String getViewerId() {
		return viewerDescriptor.getViewerId();
	}
	/**
	 * 
	 * @param aDescriptorKey
	 *            A descriptor
	 * @return The cached NavigatorContentExtension from the descriptor
	 */
	public final NavigatorContentExtension getExtension(
			INavigatorContentDescriptor aDescriptorKey) {
		return getExtension(aDescriptorKey, true);
	}
	/**
	 *