Do not export natives to runtime via js builtins object.

src/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.
 
 var $getHash;
 var $getExistingHash;
-var $mapSet;
-var $mapHas;
-var $mapDelete;
-var $setAdd;
-var $setHas;
-var $setDelete;
-var $mapFromArray;
-var $setFromArray;
 
 (function(global, utils) {
 "use strict";
 
 %CheckIsBootstrapping();
 
 // -------------------------------------------------------------------
 // Imports
 
 var GlobalMap = global.Map;
@@ skipping 455 matching lines @@
   "set", MapSet,
   "has", MapHas,
   "delete", MapDelete,
   "clear", MapClearJS,
   "forEach", MapForEach
 ]);
 
 // Expose to the global scope.
 $getHash = GetHash;
 $getExistingHash = GetExistingHash;
-$mapGet = MapGet;
-$mapSet = MapSet;
-$mapHas = MapHas;
-$mapDelete = MapDelete;
-$setAdd = SetAdd;
-$setHas = SetHas;
-$setDelete = SetDelete;
 
-$mapFromArray = function(array) {
+function MapFromArray(array) {
   var map = new GlobalMap;
   var length = array.length;
   for (var i = 0; i < length; i += 2) {
     var key = array[i];
     var value = array[i + 1];
     %_CallFunction(map, key, value, MapSet);
   }
   return map;
 };
 
-$setFromArray = function(array) {
+function SetFromArray(array) {
   var set = new GlobalSet;
   var length = array.length;
   for (var i = 0; i < length; ++i) {
     %_CallFunction(set, array[i], SetAdd);
   }
   return set;
 };
 
+// -----------------------------------------------------------------------
+// Exports
+
+utils.ExportToRuntime(function(to) {
+  to.MapGet = MapGet;
+  to.MapSet = MapSet;
+  to.MapHas = MapHas;
+  to.MapDelete = MapDelete;
+  to.SetAdd = SetAdd;
+  to.SetHas = SetHas;
+  to.SetDelete = SetDelete;
+  to.MapFromArray = MapFromArray;
+  to.SetFromArray = SetFromArray;
+});
+
 })