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/NavigatorContentService.java
/*
	 * (non-Javadoc)
	 * 
	 * @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();
	}
	/**
	 * Returns the remembered data (the NavigatorContentDescriptor) associated with
	 * an object in the viewer. This can be used to test an object's presence in the viewer.
	 * @param element
	 * @return the object stored as data in the viewer
	 */
	public Object getViewerElementData(Object element) {
		if (structuredViewerManager != null) {
			return structuredViewerManager.getData(element);
		}