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
{
		this.parentHelper = helper;
	}
	
	/**
	 * 
	 * @param cx
	 * @param dataSetFilters
	 * @param queryFilters
	 * @param temporaryComputedColumns
	 * @return
	 */
	private List prepareFilters(Context cx, List dataSetFilters, List queryFilters,
			List temporaryComputedColumns) {
		List result = new ArrayList();
		prepareFilter(cx, dataSetFilters, temporaryComputedColumns, result);
		prepareFilter(cx, queryFilters, temporaryComputedColumns, result);
		return result;
	}
	/**
	 * 
	 * @param cx
	 * @param dataSetFilters
	 * @param temporaryComputedColumns
	 * @param result
	 */
	private void prepareFilter(Context cx, List dataSetFilters, List temporaryComputedColumns, List result) {
		if (dataSetFilters != null && !dataSetFilters.isEmpty()) {
			Iterator it = dataSetFilters.iterator();
			for (int i = 0; it.hasNext(); i++) {