Typecheck chrome://help using CompilerPass.java, everything except dependency to options

chrome/browser/resources/help/help_base_page.js

Index: chrome/browser/resources/help/help_base_page.js
diff --git a/chrome/browser/resources/help/help_base_page.js b/chrome/browser/resources/help/help_base_page.js
index 578e260a5e40b731a6a96592644e6c9fb55913db..ff6203f93cbd43f0c1408aae70cdf44db5543b27 100644
--- a/chrome/browser/resources/help/help_base_page.js
+++ b/chrome/browser/resources/help/help_base_page.js
@@ -11,6 +11,10 @@
 //
 // TODO (ygorshenin@): crbug.com/313244.
 cr.define('help', function() {
+  /**
+   * @constructor
+   * @extends {HTMLDivElement}
+   */
   function HelpBasePage() {
   }
 
@@ -150,7 +154,7 @@ cr.define('help', function() {
 
     /**
      * Registers overlay.
-     * @param {HelpBasePage} overlay Overlay that should be registered.
+     * @param {help.HelpBasePage} overlay Overlay that should be registered.
      */
     registerOverlay: function(overlay) {
       this.registeredOverlays[overlay.name] = overlay;
@@ -197,7 +201,7 @@ cr.define('help', function() {
      */
     get container() {
       assert(this.isOverlay);
-      return this.pageDiv.parentNode;
+      return /** @type {HTMLDivElement} */(this.pageDiv.parentNode);

[Dan Beam, 2014/08/05 18:49:27]

why don't you make this HTMLElement instead?  Div is pretty specific and offers
no benefits, afaik.

[Vitaly Pavlenko, 2014/08/05 23:00:54]

Done.

     },
 
     /**