First run page and subscription on install fix (FF for android)

lib/ui.js

 /*
  * This file is part of Adblock Plus <http://adblockplus.org/>,
  * Copyright (C) 2006-2014 Eyeo GmbH
  *
  * Adblock Plus is free software: you can redistribute it and/or modify
  * it under the terms of the GNU General Public License version 3 as
  * published by the Free Software Foundation.
  *
  * Adblock Plus is distributed in the hope that it will be useful,
  * but WITHOUT ANY WARRANTY; without even the implied warranty of
@@ skipping 14 matching lines @@
 let {FilterStorage} = require("filterStorage");
 let {FilterNotifier} = require("filterNotifier");
 let {RequestNotifier} = require("requestNotifier");
 let {Filter} = require("filterClasses");
 let {Subscription, SpecialSubscription, DownloadableSubscription} = require("subscriptionClasses");
 let {Synchronizer} = require("synchronizer");
 let {KeySelector} = require("keySelector");
 let {Notification} = require("notification");
 let {initAntiAdblockNotification} = require("antiadblockInit");
 
-let CustomizableUI;
-try
-{
-  ({CustomizableUI}) = Cu.import("resource:///modules/CustomizableUI.jsm", null);
-}
-catch (e)
-{
-  // No built-in CustomizableUI API, use our own implementation.
-  ({CustomizableUI}) = require("customizableUI");
-}
+let CustomizableUI = null;
 
 /**
  * Filter corresponding with "disable on site" menu item (set in fillIconMent()).
  * @type Filter
  */
 let siteWhitelist = null;
 /**
  * Filter corresponding with "disable on site" menu item (set in fillIconMenu()).
  * @type Filter
  */
@@ skipping 350 matching lines @@
    */
   initDone: function()
   {
     let {WindowObserver} = require("windowObserver");
     new WindowObserver(this);
 
     // Add toolbar icon
     let {defaultToolbarPosition} = require("appSupport");
     if ("abp-toolbarbutton" in this.overlay && defaultToolbarPosition)
     {
+      try
+      {
+        ({CustomizableUI}) = Cu.import("resource:///modules/CustomizableUI.jsm", null);
+      }
+      catch (e)
+      {
+        // No built-in CustomizableUI API, use our own implementation.
+        ({CustomizableUI}) = require("customizableUI");
+      }
+      
       CustomizableUI.createWidget({
         id: "abp-toolbarbutton",
         type: "custom",
         positionAttribute: "abp-iconposition",        // For emulation only
         defaultArea: defaultToolbarPosition.parent,
         defaultBefore: defaultToolbarPosition.before, // For emulation only
         defaultAfter: defaultToolbarPosition.after,   // For emulation only
         removable: true,
         onBuild: function(document)
         {
@@ skipping 602 matching lines @@
     }
 
     return [parent, before];
   },
 
   /**
    * Toggles visibility state of the toolbar icon.
    */
   toggleToolbarIcon: function()
   {
+    if (!CustomizableUI)
+      return;
     if (this.isToolbarIconVisible())
       CustomizableUI.removeWidgetFromArea("abp-toolbarbutton");
     else
     {
       let {defaultToolbarPosition} = require("appSupport");
       CustomizableUI.addWidgetToArea("abp-toolbarbutton", defaultToolbarPosition.parent);
     }
   },
 
   /**
@@ skipping 654 matching lines @@
           command.doCommand();
       }
     }
   },
 
   /**
    * Checks whether the toolbar icon is currently displayed.
    */
   isToolbarIconVisible: function() /**Boolean*/
   {
+    if (!CustomizableUI)
+      return false;
     let placement = CustomizableUI.getPlacementOfWidget("abp-toolbarbutton");
     return !!placement;
   },
 
   /**
    * Stores the selected hotkeys, initialized when the user presses a key.
    */
   hotkeys: null,
 
   /**
@@ skipping 191 matching lines @@
   ["abp-command-contribute", "command", UI.openContributePage.bind(UI)],
   ["abp-command-contribute-hide", "command", UI.hideContributeButton.bind(UI)]
 ];
 
 onShutdown.add(function()
 {
   for (let window in UI.applicationWindows)
     if (UI.isBottombarOpen(window))
       UI.toggleBottombar(window);
 });