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
*/
	public SlotHandle getContainerSlotHandle( )
	{
		DesignElementHandle containerHandle = getContainer( );
		if ( containerHandle == null )
			return null;
		int slotID = containerHandle.findContentSlot( this );
		assert slotID != DesignElement.NO_SLOT;
		return containerHandle.getSlot( slotID );
	}
	/**
	 * Returns a handle to the given slot. If this element has no such slot,
	 * <code>null</code> will be returned.
	 * 
	 * @param slotID
	 *            the identifier of the slot for which to obtain a handle
	 * @return the handle for the requested slot
	 */
	public SlotHandle getSlot( int slotID )
	{
		int slotCount = getDefn( ).getSlotCount( );
		if ( slotCount == 0 )
		{
			return null;
		}
		assert 0 <= slotID && slotID < slotCount;
		if ( slotHandles == null )
		{
			slotHandles = new SlotHandle[slotCount];
			for ( int i = 0; i < slotCount; i++ )