Bug 121498 When datasource/dataset deleted, the datasource/dataset property binding element haven't been deleted
When deleted the datasource/dataset, the datasource/dataset property binding element haven't been deleted. Expected result: This operation must be a transaction.
model/org.eclipse.birt.report.model/src/org/eclipse/birt/report/model/api/DesignElementHandle.java
* 
	 * @param obj
	 *            the listener to register
	 */
	public void addListener( Listener obj )
	{
		getElement( ).addListener( obj );
	}
	/**
	 * Removes a given listener. If the listener registered, then the request is
	 * silently ignored.
	 * 
	 * @param obj
	 *            the listener to de-register
	 */
	public void removeListener( Listener obj )
	{
		getElement( ).removeListener( obj );
	}
	/**
	 * Returns an iterator over the elements that derive from this one.
	 * 
	 * @return an iterator over the elements that derive from this one. Each
	 *         item returned by the iterator's <code>getNext( )</code> method
	 *         is of type {@link DesignElementHandle}.
	 */
	public Iterator derivedIterator( )
	{
		return new DerivedElementIterator( module, this );
	}