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
while (changed) {
			changed = false;
			for (int i = 0, len = list.size(); i < len; i++) {
				NavigatorContentDescriptor desc = (NavigatorContentDescriptor) list.get(i);
				if (desc.getAppearsBeforeId() != null) {
					int beforeInd = findId(list, desc.getAppearsBeforeId());
					if (beforeInd < i) {
						list.add(beforeInd, desc);
						list.remove(i + 1);
						changed = true;
					}
				}
			}
		}
		
		for (int i = 0, len = list.size(); i < len; i++) {
			NavigatorContentDescriptor desc = (NavigatorContentDescriptor) list.get(i);
			desc.setSequenceNumber(i);
			if (Policy.DEBUG_EXTENSION_SETUP) {
				System.out.println("Descriptors by sequence: " + desc); 
			}
		}
	}
	private ImageRegistry getImageRegistry() {
		if (imageRegistry == null) {
			imageRegistry = new ImageRegistry();
		}
		return imageRegistry;
	}
	private class NavigatorContentDescriptorRegistry extends