Bug 139986 [CommonNavigator] Convert catch(Error/Throwable) to SafeRunner
In several places the CN framework uses catch(Error/Throwable) to ensure that code does not bring the framework down. Change these to use SafeRunner.
bundles/org.eclipse.ui.navigator/src/org/eclipse/ui/internal/navigator/extensions/LinkHelperDescriptor.java
if (expressions[0].getChildren() != null
					&& expressions[0].getChildren().length > 0) {
				selectionEnablement = new CustomAndExpression(expressions[0]);
			}
		}
	}
	/**
	 * @return Returns the id.
	 */
	public String getId() {
		return id;
	}
	/**
	 * Create a link helper instance from this descriptors class attribute.
	 * 
	 * @return An instance of the helper that is defined by the extension, or a
	 *         Skeleton Link Helper.
	 */
	public ILinkHelper createLinkHelper() {
		if (hasLinkHelperFailedCreation)
			return SkeletonLinkHelper.INSTANCE;
		try {
			return (ILinkHelper) configElement
					.createExecutableExtension(ATT_CLASS);
		} catch (Throwable t) {
			hasLinkHelperFailedCreation = true;
			NavigatorPlugin.logError(0, t.getMessage(), t);
		}
		return SkeletonLinkHelper.INSTANCE;