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/NavigatorContentDescriptorManager.java
protected final NavigatorContentDescriptor[] getDescriptors(Object anElement) {
			return getDescriptors(anElement, true);
		}
		protected final void setDescriptors(Object anElement, NavigatorContentDescriptor[] theDescriptors) {
			setDescriptors(anElement, theDescriptors, true);
		}
		protected final NavigatorContentDescriptor[] getDescriptors(Object anElement, boolean toComputeOverrides) {
			if (anElement == null)
				return null;
			NavigatorContentDescriptor[] cachedDescriptors = null;
			if (toComputeOverrides) {
				SoftReference cache = (SoftReference) evaluations.get(anElement);
				if (cache != null && (cachedDescriptors = (NavigatorContentDescriptor[]) cache.get()) == null)
					evaluations.remove(anElement);
				return cachedDescriptors;
			}
			SoftReference cache = (SoftReference) evaluationsWithOverrides.get(anElement);
			if (cache != null && (cachedDescriptors = (NavigatorContentDescriptor[]) cache.get()) == null)
				evaluationsWithOverrides.remove(anElement);
			return cachedDescriptors;
		}
		protected final void setDescriptors(Object anElement, NavigatorContentDescriptor[] theDescriptors, boolean toComputeOverrides) {
			if (anElement != null) {
				if (toComputeOverrides)
					evaluations.put(new EvalutationReference(anElement), new SoftReference(theDescriptors));
				else
					evaluationsWithOverrides.put(new EvalutationReference(anElement), new SoftReference(theDescriptors));
			}
		}
		/*