Issue 5450 - don't expose std::shared_ptr<JsEngine>

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 282 matching lines @@
      * @param parameters optional creation parameters.
      */
     static void CreateAsync(const JsEnginePtr& jsEngine,
       const OnCreatedCallback& onCreated,
       const CreationParameters& parameters = CreationParameters());
 
     /**
      * Retrieves the `JsEngine` instance associated with this `FilterEngine`
      * instance.
      */
-    JsEnginePtr GetJsEngine() const { return jsEngine; }
+    JsEngine& GetJsEngine() const { return *jsEngine; }
 
     /**
      * Checks if this is the first run of the application.
      * @return `true` if the application is running for the first time.
      */
     bool IsFirstRun() const;
 
     /**
      * Retrieves a filter object from its text representation.
      * @param text Text representation of the filter,
@@ skipping 252 matching lines @@
     void FilterChanged(const FilterChangeCallback& callback, 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