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
SlotDefn slotInfo = (SlotDefn) metaData.getSlot( slotID );
		if ( slotInfo == null )
			throw new ContentException( element, slotID,
					ContentException.DESIGN_EXCEPTION_SLOT_NOT_FOUND );
		if ( !slotInfo.canContain( content ) )
			throw new ContentException( element, slotID, content,
					ContentException.DESIGN_EXCEPTION_WRONG_TYPE );
		
		
		if ( element.isVirtualElement( )
				|| element.getExtendsElement( ) != null )
			throw new ContentException(
					element,
					slotID,
					content,
					ContentException.DESIGN_EXCEPTION_STRUCTURE_CHANGE_FORBIDDEN );
		
		if ( element.isContentOf( content ) )
			throw new ContentException( element, slotID, content,
					ContentException.DESIGN_EXCEPTION_RECURSIVE );
		
		if ( !slotInfo.isMultipleCardinality( )
				&& element.getSlot( slotID ).getCount( ) > 0 )
		{
			throw new ContentException( element, slotID,
					ContentException.DESIGN_EXCEPTION_SLOT_IS_FULL );
		}
		if ( slotID == Module.COMPONENT_SLOT )
		{
			if ( StringUtil.isBlank( content.getName( ) ) )