Do not export natives to runtime via js builtins object.

src/proxy.js

 // Copyright 2011 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 $proxyDerivedGetTrap;
-var $proxyDerivedHasTrap;
-var $proxyDerivedSetTrap;
-var $proxyEnumerate;
-
 (function(global, utils) {
 
 "use strict";
 
 %CheckIsBootstrapping();
 
 // ----------------------------------------------------------------------------
 // Imports
 
 var GlobalFunction = global.Function;
@@ skipping 172 matching lines @@
 
 //Set up non-enumerable properties of the Proxy object.
 utils.InstallFunctions(Proxy, DONT_ENUM, [
   "create", ProxyCreate,
   "createFunction", ProxyCreateFunction
 ])
 
 // -------------------------------------------------------------------
 // Exports
 
-$proxyDerivedGetTrap = DerivedGetTrap;
-$proxyDerivedHasTrap = DerivedHasTrap;
-$proxyDerivedSetTrap = DerivedSetTrap;
-$proxyEnumerate = ProxyEnumerate;
-
 utils.Export(function(to) {
   to.ProxyDelegateCallAndConstruct = DelegateCallAndConstruct;
   to.ProxyDerivedHasOwnTrap = DerivedHasOwnTrap;
   to.ProxyDerivedKeysTrap = DerivedKeysTrap;
 });
 
+utils.ExportToRuntime(function(to) {
+  to.ProxyDerivedGetTrap = DerivedGetTrap;
+  to.ProxyDerivedHasTrap = DerivedHasTrap;
+  to.ProxyDerivedSetTrap = DerivedSetTrap;
+  to.ProxyEnumerate = ProxyEnumerate;
+});
+
 })