Fix spec violations in JSON.stringify wrt replacer array.

src/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 192 matching lines @@
     gap = %_SubString("          ", 0, space);
   } else if (IS_STRING(space)) {
     if (space.length > 10) {
       gap = %_SubString(space, 0, 10);
     } else {
       gap = space;
     }
   } else {
     gap = "";
   }
+  if (IS_ARRAY(replacer)) {
+    // Deduplicate replacer array items.
+    var property_list = new InternalArray();
+    var seen_properties = {};
+    var length = replacer.length;
+    for (var i = 0; i < length; i++) {
+      var item = replacer[i];
+      if (IS_NUMBER(item)) item = %_NumberToString(item);
+      if (IS_STRING(item) && !(item in seen_properties)) {

[arv (Not doing code reviews), 2014/03/04 19:54:54]

Is this correct? What about the overlapping properties from Object.prototype?
Like toString, __proto__ and others.

[arv (Not doing code reviews), 2014/03/04 20:04:23]

We are not handling IS_OBJECT correctly here.

http://people.mozilla.org/~jorendorff/es6-draft.html#sec-json.stringify

4. Else if Type(v) is Object then,
  a. If v has a [[StringData]] or [[NumberData]] internal slot, then let item be
ToString(v).

+        property_list.push(item);
+        seen_properties[item] = true;
+      }
+    }
+    replacer = property_list;
+  }
   return JSONSerialize('', {'': value}, replacer, new InternalArray(), "", gap);
 }
 
 
 // -------------------------------------------------------------------
 
 function SetUpJSON() {
   %CheckIsBootstrapping();
 
   // Set up non-enumerable properties of the JSON object.
   InstallFunctions($JSON, DONT_ENUM, $Array(
     "parse", JSONParse,
     "stringify", JSONStringify
   ));
 }
 
 SetUpJSON();
 
 
 // -------------------------------------------------------------------
 // JSON Builtins
 
 function JSONSerializeAdapter(key, object) {
   var holder = {};
   holder[key] = object;
   // No need to pass the actual holder since there is no replacer function.
   return JSONSerialize(key, holder, UNDEFINED, new InternalArray(), "", "");
 }