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/script/internal/instance/CellInstance.java
ICellInstance
{
	private CellContent cell;
	private IRowData data;
	private boolean fromGrid;
	public CellInstance( CellContent cell, IRowData data,
			ExecutionContext context, boolean fromGrid )
	{
		super( cell, context );
		this.data = data;
		this.cell = ( CellContent ) content;
		this.fromGrid = fromGrid;
	}
	/*
	 * (non-Javadoc)
	 * 
	 * @see org.eclipse.birt.report.engine.api.script.instance.ICellInstance#getColSpan()