Issue 4085 - Fallback to XMLHttpRequest if Fetch API is not supported in Edge

lib/polyfills/fetch.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 47 matching lines @@
 
   // While the Fetch API is natively supported since Chrome 42, before
   // Chrome 47 it failed to fetch files from within the extension bundle.
   // https://code.google.com/p/chromium/issues/detail?id=466876
   var builtinFetch = global.fetch;
   if (builtinFetch)
     global.fetch = function(url, init)
     {
       return builtinFetch(url, init).catch(function(reason)
       {
-        if (new URL(url, document.URL).protocol == "chrome-extension:")
+        var protocol = new URL(url, document.URL).protocol;
+        if ((protocol == "chrome-extension:") || (protocol == "ms-browser-extension:"))

[kzar, 2016/08/22 15:47:20]

Nit: Mind wrapping this at the || to avoid the line being too long?

if ((protocol == "chrome-extension:") ||
    (protocol == "ms-browser-extension:"))
  ...
...

[kzar, 2016/08/22 15:47:20]

Not sure what Sebastian thinks but maybe we should rather check if protocol ends
with "-extension:"? Then we could avoid doing two checks and the protocol
variable.

           return fetch(url);
         throw reason;
       });
     };
   else
     global.fetch = fetch;
 })(this);