Issue 5013 - Make parameter const ref when applicable.

src/FileSystemJsObject.cpp

 /*
  * This file is part of Adblock Plus <https://adblockplus.org/>,
  * Copyright (C) 2006-2017 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 331 matching lines @@
         "_fileSystem.resolve requires 1 parameter"));
 
     std::string resolved = jsEngine->GetFileSystem()->Resolve(converted[0]->AsString());
 
     return Utils::ToV8String(isolate, resolved);
   }
 
 }
 
 
-JsValuePtr FileSystemJsObject::Setup(JsEnginePtr jsEngine, JsValuePtr obj)
+JsValuePtr FileSystemJsObject::Setup(const JsEnginePtr& jsEngine, const JsValuePtr& obj)
 {
   obj->SetProperty("read", jsEngine->NewCallback(::ReadCallback));
   obj->SetProperty("write", jsEngine->NewCallback(::WriteCallback));
   obj->SetProperty("move", jsEngine->NewCallback(::MoveCallback));
   obj->SetProperty("remove", jsEngine->NewCallback(::RemoveCallback));
   obj->SetProperty("stat", jsEngine->NewCallback(::StatCallback));
   obj->SetProperty("resolve", jsEngine->NewCallback(::ResolveCallback));
   return obj;
 }