Refactored the abstraction layer to address prerendered pages on Safari caused by leaky abstraction

safari/ext/popup.js

 (function()
 {
   // Safari doesn't adjust the size of the popover automatically to the size
   // of its content, like when the ad counter is expanded/collapsed. So we add
   // event listeners to do so.
   var mayResize = true;
   var resizingScheduled = false;
 
   var updateSize = function()
   {
@@ skipping 45 matching lines @@
   // listener to do so.
   safari.application.addEventListener("activate", function()
   {
     safari.self.hide();
   }, true);
 
 
   // import ext into the javascript context of the popover. This code might fail,
   // when the background page isn't ready yet. So it is important to put it below
   // the reloading code above.
-  var backgroundPage = safari.extension.globalPage.contentWindow;
+  window.ext = {
+    __proto__: safari.extension.globalPage.contentWindow.ext,
 
-  window.ext = {
-    __proto__: backgroundPage.ext,
     closePopup: function()
     {
       safari.self.hide();
     }
   };
-  window.TabMap = backgroundPage.TabMap;
 })();