Issue 3200 - Delay initialization for prerendered documents

composer.postload.js

 /*
  * This file is part of Adblock Plus <https://adblockplus.org/>,
  * Copyright (C) 2006-present 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 564 matching lines @@
             {
               type: "composer.content.finished"
             }
           });
         }
         break;
     }
   });
 
   if (window == window.top)
-    ext.backgroundPage.sendMessage({type: "composer.ready"});
+  {
+    whenDocumentVisible(() =>
+    {
+      ext.backgroundPage.sendMessage({type: "composer.ready"});
+    });
+  }
 }