Bug 135790 ClassCastException in RowData.
ClassCastException is thrown in RowData line 81(IBaseExpression expr = ( IBaseExpression ) valueExpressions.get( index - 1 );).
engine/org.eclipse.birt.report.engine/src/org/eclipse/birt/report/engine/executor/GridItemExecutor.java
{
			emitter.startTableBody( body );
		}
		for ( int i = 0; i < gridItem.getRowCount( ); i++ )
		{
			RowDesign row = gridItem.getRow( i );
			if ( row != null )
			{
				executeRow( i, body, row, emitter );
			}
		}
		if ( emitter != null )
		{
			emitter.endTableBody( body );
		}
		finishTOCEntry( );
		context.popContent( );
		if ( emitter != null )
		{
			emitter.endTable( tableObj );
		}
		finishTOCEntry( );
		closeResultSet( );
		context.popContent( );
	}
	/**
	 * execute the row. The execution process is:
	 * <li> create a row content
	 * <li> push it into the context
	 * <li> intialize the content.