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

src/string-iterator.js

 // Copyright 2014 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();
 
 // -------------------------------------------------------------------
 // Imports
 
 var ArrayIteratorCreateResultObject;
 var GlobalString = global.String;
+var iteratorSymbol = utils.ImportNow("iterator_symbol");
 var stringIteratorIteratedStringSymbol =
-    utils.GetPrivateSymbol("string_iterator_iterated_string_symbol");
+    utils.ImportNow("string_iterator_iterated_string_symbol");
 var stringIteratorNextIndexSymbol =
-    utils.GetPrivateSymbol("string_iterator_next_index_symbol");
+    utils.ImportNow("string_iterator_next_index_symbol");
+var toStringTagSymbol = utils.ImportNow("to_string_tag_symbol");
 
 utils.Import(function(from) {
   ArrayIteratorCreateResultObject = from.ArrayIteratorCreateResultObject;
 });
 
 // -------------------------------------------------------------------
 
 function StringIterator() {}
 
 
@@ skipping 54 matching lines @@
 }
 
 //-------------------------------------------------------------------
 
 %FunctionSetPrototype(StringIterator, {__proto__: $iteratorPrototype});
 %FunctionSetInstanceClassName(StringIterator, 'String Iterator');
 
 utils.InstallFunctions(StringIterator.prototype, DONT_ENUM, [
   'next', StringIteratorNext
 ]);
-%AddNamedProperty(StringIterator.prototype, symbolToStringTag,
+%AddNamedProperty(StringIterator.prototype, toStringTagSymbol,
                   "String Iterator", READ_ONLY | DONT_ENUM);
 
-utils.SetFunctionName(StringPrototypeIterator, symbolIterator);
-%AddNamedProperty(GlobalString.prototype, symbolIterator,
+utils.SetFunctionName(StringPrototypeIterator, iteratorSymbol);
+%AddNamedProperty(GlobalString.prototype, iteratorSymbol,
                   StringPrototypeIterator, DONT_ENUM);
 
 })