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

src/array.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();
 
 // -------------------------------------------------------------------
 // Imports
 
 var Delete;
 var GlobalArray = global.Array;
 var InternalArray = utils.InternalArray;
 var InternalPackedArray = utils.InternalPackedArray;
 var MathMin;
 var ObjectHasOwnProperty;
 var ObjectIsFrozen;
 var ObjectIsSealed;
 var ObjectToString;
 var ToNumber;
 var ToString;
+var unscopablesSymbol = utils.ImportNow("unscopables_symbol");
 
 utils.Import(function(from) {
   Delete = from.Delete;
   MathMin = from.MathMin;
   ObjectHasOwnProperty = from.ObjectHasOwnProperty;
   ObjectIsFrozen = from.ObjectIsFrozen;
   ObjectIsSealed = from.ObjectIsSealed;
   ObjectToString = from.ObjectToString;
   ToNumber = from.ToNumber;
   ToString = from.ToString;
@@ skipping 1568 matching lines @@
 var unscopables = {
   __proto__: null,
   copyWithin: true,
   entries: true,
   fill: true,
   find: true,
   findIndex: true,
   keys: true,
 };
 
-%AddNamedProperty(GlobalArray.prototype, symbolUnscopables, unscopables,
+%AddNamedProperty(GlobalArray.prototype, unscopablesSymbol, unscopables,
                   DONT_ENUM | READ_ONLY);
 
 // Set up non-enumerable functions on the Array object.
 utils.InstallFunctions(GlobalArray, DONT_ENUM, [
   "isArray", ArrayIsArray
 ]);
 
 var specialFunctions = %SpecialArrayFunctions();
 
 var getFunction = function(name, jsBuiltin, len) {
@@ skipping 84 matching lines @@
   "array_concat", ArrayConcatJS,
   "array_pop", ArrayPop,
   "array_push", ArrayPush,
   "array_shift", ArrayShift,
   "array_splice", ArraySplice,
   "array_slice", ArraySlice,
   "array_unshift", ArrayUnshift,
 ]);
 
 });