Native context: do not put public symbols and flags on the js builtins object.

src/weak-collection.js

 // Copyright 2012 the V8 project authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 (function(global, utils) {
 
 "use strict";
 
 %CheckIsBootstrapping();
 
 var GlobalObject = global.Object;
 var GlobalWeakMap = global.WeakMap;
 var GlobalWeakSet = global.WeakSet;
+var toStringTagSymbol = utils.ImportNow("to_string_tag_symbol");
 
 // -------------------------------------------------------------------
 // Harmony WeakMap
 
 function WeakMapConstructor(iterable) {
   if (!%_IsConstructCall()) {
     throw MakeTypeError(kConstructorNotFunction, "WeakMap");
   }
 
   %WeakCollectionInitialize(this);
@@ skipping 59 matching lines @@
 }
 
 
 // -------------------------------------------------------------------
 
 %SetCode(GlobalWeakMap, WeakMapConstructor);
 %FunctionSetLength(GlobalWeakMap, 0);
 %FunctionSetPrototype(GlobalWeakMap, new GlobalObject());
 %AddNamedProperty(GlobalWeakMap.prototype, "constructor", GlobalWeakMap,
                   DONT_ENUM);
-%AddNamedProperty(GlobalWeakMap.prototype, symbolToStringTag, "WeakMap",
+%AddNamedProperty(GlobalWeakMap.prototype, toStringTagSymbol, "WeakMap",
                   DONT_ENUM | READ_ONLY);
 
 // Set up the non-enumerable functions on the WeakMap prototype object.
 utils.InstallFunctions(GlobalWeakMap.prototype, DONT_ENUM, [
   "get", WeakMapGet,
   "set", WeakMapSet,
   "has", WeakMapHas,
   "delete", WeakMapDelete
 ]);
 
@@ skipping 53 matching lines @@
 }
 
 
 // -------------------------------------------------------------------
 
 %SetCode(GlobalWeakSet, WeakSetConstructor);
 %FunctionSetLength(GlobalWeakSet, 0);
 %FunctionSetPrototype(GlobalWeakSet, new GlobalObject());
 %AddNamedProperty(GlobalWeakSet.prototype, "constructor", GlobalWeakSet,
                  DONT_ENUM);
-%AddNamedProperty(GlobalWeakSet.prototype, symbolToStringTag, "WeakSet",
+%AddNamedProperty(GlobalWeakSet.prototype, toStringTagSymbol, "WeakSet",
                   DONT_ENUM | READ_ONLY);
 
 // Set up the non-enumerable functions on the WeakSet prototype object.
 utils.InstallFunctions(GlobalWeakSet.prototype, DONT_ENUM, [
   "add", WeakSetAdd,
   "has", WeakSetHas,
   "delete", WeakSetDelete
 ]);
 
 })