Fix the reviver function in JSON.parse

src/json.js

Index: src/json.js
diff --git a/src/json.js b/src/json.js
index e405f87bab6b39a6905304adbc66ebd8f421d00d..1901b07a3985e4a75e123336a8c36aeaee11f5f3 100644
--- a/src/json.js
+++ b/src/json.js
@@ -35,7 +35,11 @@ function Revive(holder, name, reviver) {
       var length = val.length;
       for (var i = 0; i < length; i++) {
         var newElement = Revive(val, %_NumberToString(i), reviver);
-        val[i] = newElement;
+        if (IS_UNDEFINED(newElement)) {
+          delete val[i];
+        } else {
+          val[i] = newElement;
+        }
       }
     } else {
       for (var p in val) {