Bug 189706 Enhance computed column aggregation function handling in UI.
Due to the issue discussed in 189705, current computed column aggregation builder in data set editor has bugs to extend: 1.When new a computed column, the aggregation argument field cannot be correctly set. 2.The argument field cannot be correct grayed out when user select a aggregation function without arguments 3.The available aggregation function list is incomprehensive 4.Some aggregation function cannot be set to model(say, weightedAve).
data/org.eclipse.birt.report.data.adapter/src/org/eclipse/birt/report/data/adapter/api/DataAdapterUtil.java
{
			return "JSResultIteratorObject";
		}
		
		public Object get( String arg0, Scriptable scope )
		{
			try
			{
				if ( this.currentIterator == null )
					return null;
				
				if( "__rownum".equalsIgnoreCase( arg0 )||"0".equalsIgnoreCase( arg0 ))
				{
					return new Integer( this.currentIterator.getRowIndex( ) );
				}
				if( "_outer".equalsIgnoreCase( arg0 ))
				{
					return new JSResultIteratorObject( it.getParent( ));
				}
				return this.currentIterator.getValue( arg0 );
			}
			catch ( BirtException e )
			{
				return null;
			}
		}
		
	}
}