Issue 4721 - Use IndexedDB for storage in Edge

lib/io.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
  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  * GNU General Public License for more details.
  *
  * You should have received a copy of the GNU General Public License
  * along with Adblock Plus.  If not, see <http://www.gnu.org/licenses/>.
  */
 
 const keyPrefix = "file:";
 
 function fileToKey(file)
 {
   return keyPrefix + (file instanceof FakeFile ? file.path : file.spec);
 }
 
 function loadFile(file, successCallback, errorCallback)
 {
   let key = fileToKey(file);
+
   // Make sure we do not have subscriptions in localStorage from older
   // versions first
   let entry = localStorage.getItem(key);
   if (typeof entry == "string")
   {
     try
     {
       entry = JSON.parse(entry);
     }
     catch(err) 
@@ skipping 11 matching lines @@
       errorCallback(new Error("File doesn't exist"));
     else
       successCallback(value);
   });
 }
 
 function saveFile(file, data, callback)
 {
   var key = fileToKey(file);
   var entry = {
-    lastModified: Date.now(),

[kzar, 2016/12/20 11:09:01]

Nit: Mind putting these keys lastModified and content in the order they used to
be? (content first, then lastModified)

[Oleksandr, 2016/12/20 14:36:50]

Done.

-    content: Array.from(data)
+    content: Array.from(data),
+    lastModified: Date.now()
   };
 
   localStorage.removeItem(key);
   localforage.setItem(key, entry, callback);
 }
+
 exports.IO =
 {
   resolveFilePath: function(path)
   {
     return new FakeFile(path);
   },
 
   readFromFile: function(file, listener, callback)
   {
     function onLoaded(entry)
@@ skipping 49 matching lines @@
     {
       callback(null, {
         exists: true,
         lastModified: entry.lastModified
       });
     }
 
     loadFile(file, onLoaded, callback);
   }
 };