Bug 211703 Support muti-view on report item.
As title described.
xtab/org.eclipse.birt.report.item.crosstab.core/src/org/eclipse/birt/report/item/crosstab/core/de/internal/CrosstabReportItemTask.java
throw new PropertyValueException( crosstab.getModelHandle( )
						.getElement( ), crosstab.getModelHandle( )
						.getPropertyDefn( MULTI_VIEWS_PROP ), null,
						PropertyValueException.DESIGN_EXCEPTION_ITEM_NOT_FOUND );
			}
			
			if ( viewElement.getContainer( ) == null )
				multiView.addView( viewElement );
			
			int newIndex = MultiViewsHandle.HOST;
			if ( viewElement != crosstab.getModelHandle( ) )
			{
				ContainerContext context = new ContainerContext( multiView
						.getElement( ), MultiViewsHandle.VIEWS_PROP );
				newIndex = context.indexOf( viewElement.getElement( ) );
				
				
				assert newIndex != -1;
			}
			multiView.setIntProperty( MultiViewsHandle.INDEX_PROP, newIndex );
		}
		catch ( SemanticException e )
		{
			stack.rollback( );
			throw e;
		}
		stack.commit( );
	}
}