Sanitize inheritance in callers of utils.expose

chrome/renderer/resources/extensions/enterprise_platform_keys/key_pair.js

 // Copyright 2014 The Chromium 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 utils = require('utils');
 var intersect = require('platformKeys.utils').intersect;
 var keyModule = require('platformKeys.Key');
 var Key = keyModule.Key;
 var KeyType = keyModule.KeyType;
 var KeyUsage = keyModule.KeyUsage;
 
 /**
  * Implementation of WebCrypto.KeyPair used in enterprise.platformKeys.
  * @param {ArrayBuffer} publicKeySpki The Subject Public Key Info in DER
  *   encoding.
  * @param {KeyAlgorithm} algorithm The algorithm identifier.
  * @param {KeyUsage[]} usages The allowed key usages.
  * @constructor
  */
-var KeyPairImpl = function(publicKeySpki, algorithm, usages) {
+function KeyPairImpl(publicKeySpki, algorithm, usages) {
   this.publicKey = new Key(KeyType.public,
                            publicKeySpki,
                            algorithm,
                            intersect([KeyUsage.verify], usages),
                            true /* extractable */);
   this.privateKey = new Key(KeyType.private,
                             publicKeySpki,
                             algorithm,
                             intersect([KeyUsage.sign], usages),
                             false /* not extractable */);
-};
+}
+$Object.setPrototypeOf(KeyPairImpl.prototype, null);
 
 function KeyPair() {
   privates(KeyPair).constructPrivate(this, arguments);
 }
 utils.expose(KeyPair, KeyPairImpl, {
   readonly: [
     'publicKey',
     'privateKey',
   ],
 });
 
 exports.$set('KeyPair', KeyPair);