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 #findContentExtensionsWithPossibleChild(Object)
	 */
	public NavigatorContentDescriptor getSourceOfContribution(Object element) {
		return (NavigatorContentDescriptor) getContributionMemory()
				.get(element);
	}
	/**
	 * @return Returns the contributionMemory.
	 */
	public Map getContributionMemory() {
		if (contributionMemory != null) {
			return contributionMemory;
		}
		synchronized (this) {
			if (contributionMemory == null) {
				contributionMemory = new WeakHashMap();
			}
		}
		return contributionMemory;
	}
	/**
	 * Search for extensions that declare the given element in their
	 * <b>triggerPoints</b> expression.
	 * 
	 * @param anElement
	 *            The element to use in the query
	 * 
	 * @return The set of {@link INavigatorContentDescriptor}s that are
	 *         <i>visible</i> and <i>active</i> for this content service and
	 *         have a <b>triggerPoints</b> expression that is <i>enabled</i> for