Bug 123726 "Top n", "Bottom n" in highlight dialog doesn't work.
Description: "Top n", "Bottom n" in highlight dialog doesn't work. Steps to reproduce: 1. Add a highlight for a table. 2. Set highlight rule: "account_id", "top n", "3", let its font color red. 3. Preview the report, it doesn't work. Attached is design file.
data/org.eclipse.birt.data/src/org/eclipse/birt/data/engine/impl/PreparedQuery.java
* @param cx
	 * @param expr
	 * @return
	 */
	private ColumnInfo getColInfoFromJSExpr( Context cx, String expr )
	{
		int colIndex = -1;
		String colName = null;
		ExpressionCompiler compiler = engine.getExpressionCompiler( );
		CompiledExpression ce = compiler.compile( expr, null, cx );
		if ( ce instanceof ColumnReferenceExpression )
		{
			ColumnReferenceExpression cre = ( (ColumnReferenceExpression) ce );
			colIndex = cre.getColumnindex( );
			colName = cre.getColumnName( );
		}
		return new ColumnInfo( colIndex, colName );
	}
	
	/**
	 * @param trans
	 * @param groupLevel
	 * @param cx
	 * @throws DataException
	 */
	private void prepareGroup( IBaseTransform trans, int groupLevel, Context cx )
		throws DataException
	{
		
		prepareExpressions( trans.getAfterExpressions(), groupLevel, true, cx );