Typecheck some of ui/webui/resources/js/ with Closure compiler.

ui/webui/resources/js/chromeos/ui_account_tweaks.js

 // Copyright (c) 2012 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 This file contains methods that allow to tweak
  * internal page UI based on the status of current user (owner/user/guest).
  * It is assumed that required data is passed via i18n strings
  * (using loadTimeData dictionary) that are filled with call to
  * AddAccountUITweaksLocalizedValues in ui_account_tweaks.cc.
@@ skipping 91 matching lines @@
       return;
     UIAccountTweaks.applySessionTypeVisibility_(document, SESSION_TYPE_PUBLIC);
   }
 
   /**
    * Disables and marks page elements for specified session type.
    * Adds #-disabled css class to all elements within given subtree,
    * disables interactive elements (input/select/button), and removes href
    * attribute from <a> elements.
    *
-   * @param {Element} element Root element of DOM subtree that should be
+   * @param {!Element} element Root element of DOM subtree that should be
    *     disabled.
    * @param {string} sessionType session type specificator.
    */
   UIAccountTweaks.disableElementsForSessionType = function(element,
                                                            sessionType) {
     UIAccountTweaks.disableElementForSessionType_(element, sessionType);
 
     // Walk the tree, searching each ELEMENT node.
     var walker = document.createTreeWalker(element,
                                            NodeFilter.SHOW_ELEMENT,
                                            null,
                                            false);
 
     var node = walker.nextNode();
     while (node) {
-      UIAccountTweaks.disableElementForSessionType_(node, sessionType);
+      if (!(node instanceof Element)) {

[arv (Not doing code reviews), 2014/07/25 18:27:13]

this is always false

[Dan Beam, 2014/07/25 21:58:18]

whoops, removed and changed back to cast

+        UIAccountTweaks.disableElementForSessionType_(
+            /** @type {!Element} */(node), sessionType);
+      }
       node = walker.nextNode();
     }
   };
 
   /**
    * Disables single element for given session type.
    * Adds *sessionType*-disabled css class, adds disabled attribute for
    * appropriate elements (input/select/button), and removes href attribute from
    * <a> element.
    *
    * @private
-   * @param {Element} element Element that should be disabled.
+   * @param {!Element} element Element that should be disabled.
    * @param {string} sessionType account session Type specificator.
    */
   UIAccountTweaks.disableElementForSessionType_ = function(element,
                                                            sessionType) {
     element.classList.add(sessionType + '-disabled');
     if (element.nodeName == 'INPUT' ||
         element.nodeName == 'SELECT' ||
-        element.nodeName == 'BUTTON')
+        element.nodeName == 'BUTTON') {
       element.disabled = true;
-    if (element.nodeName == 'A') {
+    } else if (element.nodeName == 'A') {
       element.onclick = function() {
         return false;
       };
     }
   };
 
   // Export
   return {
     UIAccountTweaks: UIAccountTweaks
   };
 
 });