Bug 136241 [regression]Preview template in web viewer and pdf didn't get correct effect.
Description: Preview template items in web viewer and pdf didn't get correct effect. Steps to reproduce: 1. Create template items. 2. Preview in Web Viewer and pdf. Expected result: Same effect as in html. Actual result: In web viewer, see only blank box. In pdf, blank page.
model/org.eclipse.birt.report.model/src/org/eclipse/birt/report/model/command/ContentCommand.java
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( ) ) )
				throw new ContentException( element, slotID, content,
						ContentException.DESIGN_EXCEPTION_CONTENT_NAME_REQUIRED );
		}
		if ( !element.canContain( module, slotID, content ) )
			throw new ContentException(
					element,
					slotID,
					content,
					ContentException.DESIGN_EXCEPTION_INVALID_CONTEXT_CONTAINMENT );
		
		TemplateCommand cmd = new TemplateCommand( module, element );