Fixes 4331, 4332 - WebSocket.length and instanceof WebSocket

include.preload.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 380 matching lines @@
         callback(event.detail);
         removeEventListener(incomingEventName, listener);
       }
       addEventListener(incomingEventName, listener);
 
       dispatchEvent(new CustomEvent(eventName, {
         detail: {url: url}
       }));
     }
 
     function WrappedWebSocket(url)

[kzar, 2016/08/15 19:29:00]

For some reason if I did this in one step I no longer had the WrappedWebSocket
reference outside of the function! Don't ask me why...

     {
       // Throw correct exceptions if the constructor is used improperly.
       if (!(this instanceof WrappedWebSocket)) return RealWebSocket();
       if (arguments.length < 1) return new RealWebSocket();
 
       var websocket;
       if (arguments.length == 1)
         websocket = new RealWebSocket(url);
       else
         websocket = new RealWebSocket(url, arguments[1]);
 
       checkRequest(websocket.url, function(blocked)
       {
         if (blocked)
           closeWebSocket(websocket);
       });
 
       return websocket;
     }
-    Object.defineProperty(WrappedWebSocket, "prototype",
-                          {value: RealWebSocket.prototype});

[kzar, 2016/08/15 19:29:00]

We have to define the prototype here so that `... instanceof WebSocket` works.

[Wladimir Palant, 2016/08/15 20:20:35]

Since the website cannot access WrappedWebSocket, just setting
WrappedWebSocket.prototype will do - no need to define a non-configurable
property.

[kzar, 2016/08/15 20:36:21]

Done.

+    WrappedWebSocket.prototype = RealWebSocket.prototype;
     WebSocket = WrappedWebSocket.bind();
     Object.defineProperties(WebSocket, {
       CONNECTING: {value: RealWebSocket.CONNECTING, enumerable: true},
       OPEN: {value: RealWebSocket.OPEN, enumerable: true},
       CLOSING: {value: RealWebSocket.CLOSING, enumerable: true},
       CLOSED: {value: RealWebSocket.CLOSED, enumerable: true},
       prototype: {value: RealWebSocket.prototype}

[kzar, 2016/08/15 19:29:00]

We have to define the prototype here so that
`WebSocket.hasOwnProperty("prototype")` is true.

     });
 
     RealWebSocket.prototype.constructor = WebSocket;
   }, eventName);
 }
 
 function init(document)
 {
   var shadow = null;
   var style = null;
@@ skipping 172 matching lines @@
   }, true);
 
   return updateStylesheet;
 }
 
 if (document instanceof HTMLDocument)
 {
   checkSitekey();
   window.updateStylesheet = init(document);
 }