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/command/ContentCommand.java
ContentRecord dropRecord = new ContentRecord( module, element, slotID,
				content, false );
		ActivityStack stack = getActivityStack( );
		stack.startFilterEventTrans( dropRecord.getLabel( ) );
		try
		{
			
			removeContents( content );
			
			dropUserProperties( content );
			if ( content.hasReferences( ) )
				adjustReferenceClients( (ReferenceableElement) content,
						unresolveReference );
			adjustReferredClients( content );
			adjustDerived( content );
			
			if ( content.getStyle( module ) != null )
			{
				StyleCommand styleCmd = new StyleCommand( module, content );
				styleCmd.setStyle( null );
			}
			
			if ( content.getExtendsElement( ) != null )
			{
				ExtendsCommand extendsCmd = new ExtendsCommand( module, content );
				extendsCmd.setExtendsName( null );
			}
			
			if ( content.getName( ) != null )
			{