Issue 4223 - Adapt filter storage read/write tests to work in adblockpluscore repository

test/filterStorage_readwrite.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 42 matching lines @@
   {
     if (error)
       reject(error);
     else
       resolve(data);
   });
 });
 
 function loadFilters(file)
 {
-  return Promise.resolve().then(() =>
-  {
-    FilterStorage.loadFromDisk(file);
-    return FilterNotifier.once("load");
-  });
+  FilterStorage.loadFromDisk(file);
+  return FilterNotifier.once("load");
 }
 
 function saveFilters(file)
 {
-  return Promise.resolve().then(() =>
-  {
-    FilterStorage.saveToDisk(file);
-    return FilterNotifier.once("save");
-  });
+  FilterStorage.saveToDisk(file);
+  return FilterNotifier.once("save");
 }
 
 function testReadWrite(test, withExternal)
 {
   let tempFile = IO.resolveFilePath("temp_patterns1.ini");
   let tempFile2 = IO.resolveFilePath("temp_patterns2.ini");
 
   function canonize(data)
   {
     let curSection = null;
@@ skipping 201 matching lines @@
     backupFile.lastModifiedTime -= 25*60*60*1000;
     oldModifiedTime = backupFile2.lastModifiedTime;
     return saveFilters(null);
   }).then(() =>
   {
     test.notEqual(backupFile2.lastModifiedTime, oldModifiedTime, "Second backup overwritten if first one is 25 hours old");
 
     test.ok(!backupFile3.exists(), "Third backup not created with patternsbackups = 2");
   }).catch(unexpectedError.bind(test)).then(() => test.done());
 };