Bug 121687 Exception throws when export data in table which inside a grid cell.
Description: Exception throws when export data in table which inside a grid cell. Steps to reproduce: 1. insert a grid. 2. insert one table to one grid cell. 3. insert another table to the other grid cell. 4. export data in two tables. Expected result: Data are exported. Actual result: Exception in: ReportEngineService.getMetaData( )
engine/org.eclipse.birt.report.engine/src/org/eclipse/birt/report/engine/parser/EngineIRVisitor.java
labelItem.setHelpText( handle.getHelpTextKey( ), handle.getHelpText( ) );
		currentElement = labelItem;
	}
	public void visitDataItem( DataItemHandle handle )
	{
		
		DataItemDesign data = new DataItemDesign( );
		setupReportItem( data, handle );
		
		String expr = handle.getValueExpr( );
		data.setValue( createExpression( expr ) );
		
		ActionHandle action = handle.getActionHandle( );
		if ( action != null )
		{
			data.setAction( createAction( action ) );
		}
		
		data.setHelpText( handle.getHelpTextKey( ), handle.getHelpText( ) );
		setHighlight( data, expr );
		setMap( data, expr );
		currentElement = data;
	}
	public void visitGrid( GridHandle handle )
	{
		
		GridItemDesign grid = new GridItemDesign( );
		setupReportItem( grid, handle );