Guard @@isConcatSpreadable behind a flag

src/harmony-array.js

 // Copyright 2013 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();
 
@@ skipping 269 matching lines @@
   var array = %IsConstructor(constructor) ? new constructor(length) : [];
   for (var i = 0; i < length; i++) {
     AddArrayElement(constructor, array, i, %_Arguments(i));
   }
   array.length = length;
   return array;
 }
 
 // -------------------------------------------------------------------
 
-utils.InstallConstants(GlobalSymbol, [
-  // TODO(dslomov, caitp): Move to symbol.js when shipping
-  "isConcatSpreadable", symbolIsConcatSpreadable
-]);
-
 %FunctionSetLength(ArrayCopyWithin, 2);
 %FunctionSetLength(ArrayFrom, 1);
 %FunctionSetLength(ArrayFill, 1);
 %FunctionSetLength(ArrayFind, 1);
 %FunctionSetLength(ArrayFindIndex, 1);
 
 // Set up non-enumerable functions on the Array object.
 utils.InstallFunctions(GlobalArray, DONT_ENUM, [
   "from", ArrayFrom,
   "of", ArrayOf
@@ skipping 12 matching lines @@
 
 utils.Export(function(to) {
   to.ArrayFrom = ArrayFrom;
   to.InnerArrayCopyWithin = InnerArrayCopyWithin;
   to.InnerArrayFill = InnerArrayFill;
   to.InnerArrayFind = InnerArrayFind;
   to.InnerArrayFindIndex = InnerArrayFindIndex;
 });
 
 })