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/actions/CommonActionProviderDescriptor.java
* @return True if and only if the extension is enabled for each element in
	 *         the selection.
	 */
	public boolean isEnabledFor(IStructuredSelection aStructuredSelection) {
		if (enablement == null) {
			return false;
		}
		
		if(aStructuredSelection.isEmpty()) {
			IEvaluationContext context = null; 
			context = NavigatorPlugin.getEmptyEvalContext();
			if (NavigatorPlugin.safeEvaluate(enablement, context) != EvaluationResult.TRUE) {
				return false;
			}
		} else {
			IEvaluationContext context = null;
			IEvaluationContext parentContext = NavigatorPlugin.getApplicationContext();
			Iterator elements = aStructuredSelection.iterator();
			while (elements.hasNext()) {
				context = new EvaluationContext(parentContext, elements.next());
				context.setAllowPluginActivation(true);
				if (NavigatorPlugin.safeEvaluate(enablement, context) != EvaluationResult.TRUE) {
					return false;
				}
			}
		}
		return true;
	}
	/**
	 * Determine if this content extension is enabled for the given element.