[proxies] Support proxies in JSON.parse and JSON.stringify.

src/js/json.js

Index: src/js/json.js
diff --git a/src/js/json.js b/src/js/json.js
index d42b8c794a77887d4991b7a2686bd4d246f3adac..b2f5b4acec6df494165b504978d1de418af9c44b 100644
--- a/src/js/json.js
+++ b/src/js/json.js
@@ -12,6 +12,7 @@
 // Imports
 
 var GlobalJSON = global.JSON;
+var GlobalSet = global.Set;
 var InternalArray = utils.InternalArray;
 var MakeTypeError;
 var MaxSimple;
@@ -30,27 +31,33 @@ utils.Import(function(from) {
 
 // -------------------------------------------------------------------
 
+function CreateDataProperty(o, p, v) {
+  var desc = {value: v, enumerable: true, writable: true, configurable: true};
+  return %reflect_define_property(o, p, desc);
+}
+
+
 function InternalizeJSONProperty(holder, name, reviver) {
   var val = holder[name];
-  if (IS_OBJECT(val) && val !== null) {
-    if (IS_ARRAY(val)) {
-      var length = val.length;
+  if (IS_SPEC_OBJECT(val)) {
+    if (%is_arraylike(val)) {
+      var length = TO_LENGTH(val.length);
       for (var i = 0; i < length; i++) {
         var newElement =
             InternalizeJSONProperty(val, %_NumberToString(i), reviver);
         if (IS_UNDEFINED(newElement)) {
-          delete val[i];
+          %reflect_delete_property(val, i);
         } else {
-          val[i] = newElement;
+          CreateDataProperty(val, i, newElement);
         }
       }
     } else {
       for (var p of ObjectKeys(val)) {
         var newElement = InternalizeJSONProperty(val, p, reviver);
         if (IS_UNDEFINED(newElement)) {
-          delete val[p];
+          %reflect_delete_property(val, p);
         } else {
-          val[p] = newElement;
+          CreateDataProperty(val, p, newElement);
         }
       }
     }
@@ -74,7 +81,7 @@ function SerializeArray(value, replacer, stack, indent, gap) {
   var stepback = indent;
   indent += gap;
   var partial = new InternalArray();
-  var len = value.length;
+  var len = TO_LENGTH(value.length);
   for (var i = 0; i < len; i++) {
     var strP = JSONSerialize(%_NumberToString(i), value, replacer, stack,
                              indent, gap);
@@ -106,27 +113,23 @@ function SerializeObject(value, replacer, stack, indent, gap) {
   if (IS_ARRAY(replacer)) {
     var length = replacer.length;
     for (var i = 0; i < length; i++) {
-      if (HAS_OWN_PROPERTY(replacer, i)) {
-        var p = replacer[i];
-        var strP = JSONSerialize(p, value, replacer, stack, indent, gap);
-        if (!IS_UNDEFINED(strP)) {
-          var member = %QuoteJSONString(p) + ":";
-          if (gap != "") member += " ";
-          member += strP;
-          partial.push(member);
-        }
+      var p = replacer[i];
+      var strP = JSONSerialize(p, value, replacer, stack, indent, gap);
+      if (!IS_UNDEFINED(strP)) {
+        var member = %QuoteJSONString(p) + ":";
+        if (gap != "") member += " ";
+        member += strP;
+        partial.push(member);
       }
     }
   } else {
-    for (var p in value) {
-      if (HAS_OWN_PROPERTY(value, p)) {
-        var strP = JSONSerialize(p, value, replacer, stack, indent, gap);
-        if (!IS_UNDEFINED(strP)) {
-          var member = %QuoteJSONString(p) + ":";
-          if (gap != "") member += " ";
-          member += strP;
-          partial.push(member);
-        }
+    for (var p of ObjectKeys(value)) {
+      var strP = JSONSerialize(p, value, replacer, stack, indent, gap);
+      if (!IS_UNDEFINED(strP)) {
+        var member = %QuoteJSONString(p) + ":";
+        if (gap != "") member += " ";
+        member += strP;
+        partial.push(member);
       }
     }
   }
@@ -166,7 +169,7 @@ function JSONSerialize(key, holder, replacer, stack, indent, gap) {
     return "null";
   } else if (IS_SPEC_OBJECT(value) && !IS_CALLABLE(value)) {
     // Non-callable object. If it's a primitive wrapper, it must be unwrapped.
-    if (IS_ARRAY(value)) {
+    if (%is_arraylike(value)) {
       return SerializeArray(value, replacer, stack, indent, gap);
     } else if (IS_NUMBER_WRAPPER(value)) {
       value = TO_NUMBER(value);
@@ -185,14 +188,13 @@ function JSONSerialize(key, holder, replacer, stack, indent, gap) {
 
 
 function JSONStringify(value, replacer, space) {
-  if (%_ArgumentsLength() == 1) {
+  if (%_ArgumentsLength() == 1 && !%_IsJSProxy(value)) {
     return %BasicJSONStringify(value);
   }
-  if (IS_ARRAY(replacer)) {
-    // Deduplicate replacer array items.
+  if (!IS_CALLABLE(replacer) && %is_arraylike(replacer)) {
     var property_list = new InternalArray();
-    var seen_properties = { __proto__: null };
-    var length = replacer.length;
+    var seen_properties = new GlobalSet();
+    var length = TO_LENGTH(replacer.length);
     for (var i = 0; i < length; i++) {
       var v = replacer[i];
       var item;
@@ -205,9 +207,9 @@ function JSONStringify(value, replacer, space) {
       } else {
         continue;
       }
-      if (!seen_properties[item]) {
+      if (!seen_properties.has(item)) {
         property_list.push(item);
-        seen_properties[item] = true;
+        seen_properties.add(item);
       }
     }
     replacer = property_list;