WebUI: Undo some usages of ES6 features that break uglify.

chrome/browser/resources/settings/route.js

 // Copyright 2016 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.
 
 cr.define('settings', function() {
   /**
    * Class for navigable routes. May only be instantiated within this file.
    * @constructor
    * @param {string} path
    * @private
@@ skipping 294 matching lines @@
    * Helper function to set the current route and notify all observers.
    * @param {!settings.Route} route
    * @param {!URLSearchParams} queryParameters
    * @param {boolean} isPopstate
    */
   var setCurrentRoute = function(route, queryParameters, isPopstate) {
     var oldRoute = currentRoute_;
     currentRoute_ = route;
     currentQueryParameters_ = queryParameters;
     lastRouteChangeWasPopstate_ = isPopstate;
-    for (var observer of routeObservers_)
+    routeObservers_.forEach(function(observer) {
       observer.currentRouteChanged(currentRoute_, oldRoute);
+    });
   };
 
   /** @return {!settings.Route} */
   var getCurrentRoute = function() { return currentRoute_; };
 
   /** @return {!URLSearchParams} */
   var getQueryParameters = function() {
     return new URLSearchParams(currentQueryParameters_);  // Defensive copy.
   };
 
@@ skipping 57 matching lines @@
     RouteObserverBehavior: RouteObserverBehavior,
     getRouteForPath: getRouteForPath,
     initializeRouteFromUrl: initializeRouteFromUrl,
     getCurrentRoute: getCurrentRoute,
     getQueryParameters: getQueryParameters,
     lastRouteChangeWasPopstate: lastRouteChangeWasPopstate,
     navigateTo: navigateTo,
     navigateToPreviousRoute: navigateToPreviousRoute,
   };
 });