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
.next();
				overriddenDescriptor = (NavigatorContentDescriptor) allDescriptors
						.get(descriptor.getSuppressedExtensionId());
				if (overriddenDescriptor != null) {
					if (Policy.DEBUG_EXTENSION_SETUP) {
						System.out.println(descriptor + " overrides: " + overriddenDescriptor); 
					}
					/*
					 * add the descriptor as an overriding extension for its
					 * suppressed extension
					 */
					overriddenDescriptor.getOverriddingExtensions().add(
							descriptor);
					descriptor.setOverriddenDescriptor(overriddenDescriptor);
					/*
					 * the always policy implies this is also a top-level
					 * extension
					 */
					if (descriptor.getOverridePolicy() == OverridePolicy.InvokeAlwaysRegardlessOfSuppressedExt) {
						if (Policy.DEBUG_EXTENSION_SETUP) {
							System.out.println(descriptor + " is first class"); 
						}
						firstClassDescriptorsMap.put(descriptor.getId(),
								descriptor);
						firstClassDescriptorsSet.add(descriptor);
					}
				} else {
					String message = 
							"Invalid suppressedExtensionId \"" 
									+ descriptor.getSuppressedExtensionId()