Bug 121864 Report element can't be deleted
Description: Report element can't be deleted Steps to reproduce: 1.Open the attached design file 2.Delete the table/parameters/dataset/datasource Expected result: The element can be deleted Actual result: They can't be deleted
model/org.eclipse.birt.report.model/src/org/eclipse/birt/report/model/command/ContentCommand.java
* @param slotID
	 *            the slot from which to replace the old element
	 * @param unresolveReference
	 *            status whether to un-resolve the references or set the
	 *            reference to null
	 * @throws SemanticException
	 *             if the old element cannot be replaced by the new element into
	 *             this container.
	 */
	private void doReplace( DesignElement oldElement, DesignElement newElement,
			int slotID, boolean unresolveReference ) throws SemanticException
	{
		assert newElement.getContainer( ) == null;
		
		ElementDefn metaData = (ElementDefn) element.getDefn( );
		if ( !metaData.isContainer( ) )
			throw new ContentException( element, slotID,
					ContentException.DESIGN_EXCEPTION_NOT_CONTAINER );
		SlotDefn slotInfo = (SlotDefn) metaData.getSlot( slotID );
		if ( slotInfo == null )
			throw new ContentException( element, slotID,
					ContentException.DESIGN_EXCEPTION_SLOT_NOT_FOUND );
		if ( !slotInfo.canContain( newElement ) )
			throw new ContentException( element, slotID, newElement,
					ContentException.DESIGN_EXCEPTION_WRONG_TYPE );
		
		if ( element.isContentOf( newElement ) )
			throw new ContentException( element, slotID, newElement,
					ContentException.DESIGN_EXCEPTION_RECURSIVE );
		if ( slotID == Module.COMPONENT_SLOT )