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
String propName = (String) iter.next( );
			setProperty( propName, properties.get( propName ) );
		}
	}
	/**
	 * Clears all the content within the given slot. If this operation should be
	 * treated as a whole, execution should be in a transaction.
	 * 
	 * @param slotId
	 *            id of the slot to be cleared.
	 * @throws SemanticException
	 */
	public void clearContents( int slotId ) throws SemanticException
	{
		SlotHandle slotHandle = getSlot( slotId );
		if ( slotHandle == null )
			return;
		for ( int i = slotHandle.getCount( ) - 1; i >= 0; i-- )
		{
			slotHandle.dropAndClear( i );
		}
	}
	/**
	 * Removes an existing user property definition from the element. This
	 * method will remove all existing values for the property, in both this
	 * element and all its derived elements.
	 * 
	 * @param propName
	 *            the name of the user property to remove
	 * @throws UserPropertyException