refs #2896 fixed Expression to use Object.keys instead of Object.getOwnPropertyNames due to inconsistencies in ordering

lib/pipeline/expressions/Expression.js

@@ -221,7 +221,7 @@ klass.parseObject = function parseObject(obj, ctx){
 		expr, // the result
 		exprObj; // the alt result
 	if (obj === undefined) return new ObjectExpression();
-	var fieldNames = Object.getOwnPropertyNames(obj);
+	var fieldNames = Object.keys(obj);
 	for (var fc = 0, n = fieldNames.length; fc < n; ++fc) {
 		var fn = fieldNames[fc];
 		if (fn[0] === "$") {