MD Settings: allow subpages not wrapped in templates

chrome/browser/resources/settings/settings_page/settings_animated_pages.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-animated-pages' is a container for a page and animated subpages.
  * It provides a set of common behaviors and animations.
  *
  * Example:
@@ skipping 109 matching lines @@
 
   /**
    * Ensures that the template enclosing the subpage is stamped.
    * @private
    */
   ensureSubpageInstance_: function() {
     var id = this.currentRoute.subpage.slice(-1)[0];
     var template = Polymer.dom(this).querySelector(
         'template[name="' + id + '"]');
 
-    // Do nothing if the subpage is already stamped.
-    if (template.if)
+    // Nothing to do if the subpage isn't wrapped in a <template> or the
+    // template is already stamped.
+    if (!template || template.if)
       return;
 
     // Set the subpage's id for use by neon-animated-pages.
     var subpage = /** @type {{_content: DocumentFragment}} */(template)._content
         .querySelector('settings-subpage');
     if (!subpage.id)
       subpage.id = id;
 
     // Render synchronously so neon-animated-pages can select the subpage.
     template.if = true;
     template.render();
   },
 
   /**
    * Buttons in this pageset should use this method to transition to subpages.
    */
   setSubpageChain: function(subpage) {
     this.currentRoute = {
       page: this.currentRoute.page,
       section: subpage.length > 0 ? this.section : '',
       subpage: subpage,
     };
   },
 });