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
}
		return navigatorExtensionStateService;
	}
	/**
	 * Non-API method to return a shell.
	 * 
	 * @return A shell associated with the current viewer (if any) or
	 *         <b>null</b>.
	 */
	public Shell getShell() {
		if (structuredViewerManager != null
				&& structuredViewerManager.getViewer() != null) {
			return structuredViewerManager.getViewer().getControl().getShell();
		}
		return null;
	}
	protected boolean isRootExtension(String anExtensionId) {
		return assistant.isRootExtension(anExtensionId);
	}
	/*
	 * (non-Javadoc)
	 * 
	 * @see
	 * org.eclipse.ui.internal.navigator.INavigatorContentService#removeListener
	 * (
	 * org.eclipse.ui.internal.navigator.extensions.INavigatorContentServiceListener
	 * )
	 */
	public void removeListener(INavigatorContentServiceListener aListener) {
		listeners.remove(aListener);