JSON.parse: properly deal with reviver result

test/mjsunit/json.js

 // Copyright 2009 the V8 project authors. All rights reserved.
 // Redistribution and use in source and binary forms, with or without
 // modification, are permitted provided that the following conditions are
 // met:
 //
 //     * Redistributions of source code must retain the above copyright
 //       notice, this list of conditions and the following disclaimer.
 //     * Redistributions in binary form must reproduce the above
 //       copyright notice, this list of conditions and the following
 //       disclaimer in the documentation and/or other materials provided
@@ skipping 122 matching lines @@
   function Filter(key, value) {
     return (key == name) ? undefined : value;
   }
   return Filter;
 }
 
 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;
 }
 
 var deepObject = '{"a": {"b": 1, "c": 2}, "d": {"e": {"f": 3}}}';
 assertEquals({"a": {"b": 1, "c": 2}, "d": {"e": {"f": 3}}},
              JSON.parse(deepObject));
 assertEquals({"a": {"b": 2, "c": 4}, "d": {"e": {"f": 6}}},
              JSON.parse(deepObject, DoubleNumbers));
@@ skipping 319 matching lines @@
 var o2 = JSON.parse('{"__proto__":5}');
 assertEquals(5, o2.__proto__);
 assertEquals(["__proto__"], Object.keys(o2));
 assertEquals(5, Object.getOwnPropertyDescriptor(o2, "__proto__").value);
 assertEquals(["__proto__"], Object.getOwnPropertyNames(o2));
 assertTrue(o2.hasOwnProperty("__proto__"));
 assertTrue(Object.prototype.isPrototypeOf(o2));
 
 var json = '{"stuff before slash\\\\stuff after slash":"whatever"}';
 TestStringify(json, JSON.parse(json));