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

chrome/browser/resources/settings/site_settings/cookie_tree_node.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.
 
 /**
  * @typedef {{title: string,
  *            id: string,
  *            data: CookieDetails}}
  */
 var CookieDataItem;
@@ skipping 116 matching lines @@
       var node = id == null ? this : this.fetchNodeById(id, true);
       node.children_.splice(firstChild, count);
     },
 
     /**
      * Returns an array of cookies from the current node within the cookie tree.
      * @return {!Array<!CookieDataItem>} The Cookie List.
      */
     getCookieList: function() {
       var list = [];
-      for (var child of this.children_) {
-        for (var cookie of child.children_) {
+      for (var i = 0; i < this.children_.length; i++) {
+        var child = this.children_[i];
+        for (var j = 0; j < child.children_.length; j++) {
+          var cookie = child.children_[j];
           list.push({title: cookie.data.title,
                      id: cookie.data.id,
                      data: cookie.data});
         }
       }
 
       return list;
     },
 
     /**
@@ skipping 75 matching lines @@
           return this.children_[i];
       }
       return null;
     },
   };
 
   return {
     CookieTreeNode: CookieTreeNode,
   };
 });