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
if ( parentAndProtoScope == null )
			parentAndProtoScope = sharedScope;
		
		Context cx = Context.enter( );
		try
		{
			Scriptable scope = cx.newObject( parentAndProtoScope );
			scope.setParentScope( parentAndProtoScope );
			scope.setPrototype( parentAndProtoScope );
			return scope;
		}
		finally
		{
			Context.exit( );
		}
	}
	
	/*
	 * @see org.eclipse.birt.data.engine.impl.IQueryExecutor#getNestedLevel()
	 */
	public int getNestedLevel( )
	{
		return this.nestedLevel;
	}
	/*
	 * @see org.eclipse.birt.data.engine.impl.IQueryExecutor#getDataSourceInstanceHandle()
	 */
	public IDataSourceInstanceHandle getDataSourceInstanceHandle( )
	{
		return this.dataSource;