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/NavigatorContentDescriptor.java
public String getId() {
		return id;
	}
	/*
	 * (non-Javadoc)
	 * 
	 * @see org.eclipse.ui.internal.navigator.extensions.INavigatorContentDescriptor#getName()
	 */
	public String getName() {
		return name;
	}
	/*
	 * (non-Javadoc)
	 * 
	 * @see org.eclipse.ui.internal.navigator.extensions.INavigatorContentDescriptor#getPriority()
	 */
	public int getPriority() {
		return priority;
	}
	/**
	 * @return the sequence number
	 */
	public int getSequenceNumber() {
		return sequenceNumber;
	}
	void setSequenceNumber(int num) {
		sequenceNumber = num;
	}
	
	/**