Issue #3593, #1197- fix isolate management

test/Prefs.cpp

 /*
  * This file is part of Adblock Plus <https://adblockplus.org/>,
  * Copyright (C) 2006-2015 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 63 matching lines @@
     {
       fileSystem = new TestFileSystem();
       fileSystemPtr.reset(fileSystem);
 
       Reset();
     }
 
     void Reset(const AdblockPlus::FilterEngine::Prefs& preconfiguredPrefs =
                AdblockPlus::FilterEngine::Prefs())
     {
-      jsEngine = AdblockPlus::JsEngine::New();
+      jsEngine = createJsEngine();
       jsEngine->SetLogSystem(AdblockPlus::LogSystemPtr(new LazyLogSystem));
       jsEngine->SetFileSystem(fileSystemPtr);
       jsEngine->SetWebRequest(AdblockPlus::WebRequestPtr(new LazyWebRequest));
 
       filterEngine.reset(
         new AdblockPlus::FilterEngine(jsEngine, preconfiguredPrefs));
     }
   };
 }
 
@@ skipping 100 matching lines @@
 
   AdblockPlus::Sleep(100);
 
   ASSERT_FALSE(fileSystem->prefsContents.empty());
 
   Reset(preconfiguredPrefs);
 
   ASSERT_TRUE(filterEngine->GetPref("suppress_first_run_page")->IsBool());
   ASSERT_FALSE(filterEngine->GetPref("suppress_first_run_page")->AsBool());
 }