Issue 3823 - Adapt message names used by "Block element" feature for consistency

block.js

 /*
  * This file is part of Adblock Plus <https://adblockplus.org/>,
  * Copyright (C) 2006-2016 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 37 matching lines @@
 }
 
 function closeDialog(success)
 {
   ext.backgroundPage.sendMessage(
   {
     type: "forward",
     targetPageId: targetPageId,
     payload:
     {
-      type: "blockelement-finished",
+      type: "composer.content.finished",
       remove: (typeof success == "boolean" ? success : false)
     }
   });
   window.close();
 }
 
 function init()
 {
   // Attach event listeners
   window.addEventListener("keydown", onKeyDown, false);
 
   document.getElementById("addButton").addEventListener("click", addFilters);
   document.getElementById("cancelButton").addEventListener(
     "click", closeDialog.bind(null, false)
   );
 
   // Apply jQuery UI styles
   $("button").button();
 
   document.getElementById("filters").focus();
 
   ext.onMessage.addListener(function(msg, sender, sendResponse)
   {
     switch (msg.type)
     {
-      case "blockelement-popup-init":
+      case "composer.dialog.init":
         targetPageId = msg.sender;
         document.getElementById("filters").value = msg.filters.join("\n");
         break;
-      case "blockelement-close-popup":
+      case "composer.dialog.close":
         window.close();
         break;
     }
   });
 
   window.removeEventListener("load", init);
 }
 window.addEventListener("load", init, false);