MD Settings: fix a couple errors

chrome/browser/resources/settings/settings_menu/settings_menu.js

 // Copyright 2015 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.
 
 /**
  * @fileoverview
  * 'settings-menu' shows a menu with a hardcoded set of pages and subpages.
  */
 Polymer({
   is: 'settings-menu',
 
   properties: {
     /** @private */
     advancedOpened_: Boolean,
 
     /**
      * The current active route.
      * @type {!settings.Route}
      */
     currentRoute: {
       type: Object,
       notify: true,
-      observer: 'currentRouteChanged_',
     },
 
     /**
      * Dictionary defining page visibility.
      * @type {!GuestModePageVisibility}
      */
     pageVisibility: {
       type: Object,
     },
   },
@@ skipping 46 matching lines @@
 
   /**
    * @param {boolean} opened Whether the menu is expanded.
    * @return {string} Which icon to use.
    * @private
    * */
   arrowState_: function(opened) {
     return opened ? 'settings:arrow-drop-up' : 'cr:arrow-drop-down';
   },
 });