Issue 5013 - Make parameter const ref when applicable.

include/AdblockPlus/FilterEngine.h

 /*
  * 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 188 matching lines @@
      */
     typedef std::function<void(const std::string&)> UpdateCheckDoneCallback;
 
     /**
      * Callback type invoked when the filters change.
      * The first parameter is the action event code (see
      * [FilterNotifier.triggerListeners](https://adblockplus.org/jsdoc/adblockpluscore/FilterNotifier.html#.triggerListeners)
      * for the full list).
      * The second parameter is the filter/subscription object affected, if any.
      */
-    typedef std::function<void(const std::string&, const JsValuePtr&)> FilterChangeCallback;
+    typedef std::function<void(const std::string&, const JsValue&)> FilterChangeCallback;
 
     /**
      * Container of name-value pairs representing a set of preferences.
      */
     typedef std::map<std::string, AdblockPlus::JsValuePtr> Prefs;
 
     /**
      * Callback type invoked when a new notification should be shown.
      * The parameter is the Notification object to be shown.
      */
@@ skipping 322 matching lines @@
       const JsValueList& params) const;
     FilterPtr GetWhitelistingFilter(const std::string& url,
       ContentTypeMask contentTypeMask, const std::string& documentUrl) const;
     FilterPtr GetWhitelistingFilter(const std::string& url,
       ContentTypeMask contentTypeMask,
       const std::vector<std::string>& documentUrls) const;
   };
 }
 
 #endif