Bug 139346 Using isTopN in table inside list group header doesn't work.
Description: Using isTopN in table inside list group header doesn't work. Steps to reproduce: 1.Insert a list with a group 2.Insert a table to list group header 3.Using Total.isTopN(row[],2,null,0) as filter expression in table item. 4.Preview Result: Only the first group displayed top 2 records, other groups kept display all records.
data/org.eclipse.birt.data/src/org/eclipse/birt/data/engine/impl/QueryExecutor.java
Context.exit();
		}
	}
	/**
	 * @param src
	 * @return
	 */
	private String getGroupKeyExpression( IGroupDefinition src )
	{
		String expr = src.getKeyColumn();
		if( expr == null )
		{
			expr = src.getKeyExpression();
		}else
		{
			expr = getColumnRefExpression(expr);
		}
		return expr;
	}
	/**
	 * 
	 * @param expr
	 * @return
	 */
	private String getColumnRefExpression(String expr) 
	{
		return "row[\""+ JavascriptEvalUtil.transformToJsConstants( expr )+ "\"]";
	}
	
	void setParentExecutorHelper( IExecutorHelper helper )