JSON.parse: properly deal with reviver result

test/mjsunit/json.js

Index: test/mjsunit/json.js
diff --git a/test/mjsunit/json.js b/test/mjsunit/json.js
index c72c153688c76312c273e0cfb20e63bc8df89170..061189589f1e96b8816d6289d4c6ffc80ece4882 100644
--- a/test/mjsunit/json.js
+++ b/test/mjsunit/json.js
@@ -140,9 +140,16 @@ var pointJson = '{"x": 1, "y": 2}';
 assertEquals({'x': 1, 'y': 2}, JSON.parse(pointJson));
 assertEquals({'x': 1}, JSON.parse(pointJson, GetFilter('y')));
 assertEquals({'y': 2}, JSON.parse(pointJson, GetFilter('x')));
+
 assertEquals([1, 2, 3], JSON.parse("[1, 2, 3]"));
-assertEquals([1, undefined, 3], JSON.parse("[1, 2, 3]", GetFilter(1)));
-assertEquals([1, 2, undefined], JSON.parse("[1, 2, 3]", GetFilter(2)));
+
+var array1 = JSON.parse("[1, 2, 3]", GetFilter(1));
+assertEquals([1, , 3], array1);
+assertFalse(array1.hasOwnProperty(1));  // assertEquals above is not enough
+
+var array2 = JSON.parse("[1, 2, 3]", GetFilter(2));
+assertEquals([1, 2, ,], array2);
+assertFalse(array2.hasOwnProperty(2));
 
 function DoubleNumbers(key, value) {
   return (typeof value == 'number') ? 2 * value : value;