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

lib/ui.js

Index: lib/ui.js
===================================================================
--- a/lib/ui.js
+++ b/lib/ui.js
@@ -32,16 +32,7 @@
 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()).
@@ -412,6 +403,16 @@
     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",
@@ -1034,6 +1035,8 @@
    */
   toggleToolbarIcon: function()
   {
+    if (!CustomizableUI)
+      return;
     if (this.isToolbarIconVisible())
       CustomizableUI.removeWidgetFromArea("abp-toolbarbutton");
     else
@@ -1708,6 +1711,8 @@
    */
   isToolbarIconVisible: function() /**Boolean*/
   {
+    if (!CustomizableUI)
+      return false;
     let placement = CustomizableUI.getPlacementOfWidget("abp-toolbarbutton");
     return !!placement;
   },