Freshen v0 polyfill

Author: javan

polyfills/vendor/CustomElements.js

@@ -7,7 +7,7 @@
  * Code distributed by Google as part of the polymer project is also
  * subject to an additional IP rights grant found at http://polymer.github.io/PATENTS.txt
  */
-// @version 0.7.22
+// @version 0.7.24
 if (typeof WeakMap === "undefined") {
   (function() {
     var defineProperty = Object.defineProperty;
@@ -351,7 +351,7 @@ if (typeof WeakMap === "undefined") {
 
 (function(scope) {
   "use strict";
-  if (!window.performance) {
+  if (!(window.performance && window.performance.now)) {
     var start = Date.now();
     window.performance = {
       now: function() {