Don`t use references to JsEngine to avoid use-after-free errors,switch to shared_ptr instead

src/WebRequestJsObject.cpp

 #include <map>
-#include <AdblockPlus/JsEngine.h>
 #include <AdblockPlus/JsValue.h>
 #include <AdblockPlus/WebRequest.h>
 #include "WebRequestJsObject.h"
 #include "Thread.h"
 
 namespace
 {
   class WebRequestThread : public AdblockPlus::Thread
   {
   public:
-    WebRequestThread(AdblockPlus::JsEngine& jsEngine, AdblockPlus::JsValueList& arguments)
+    WebRequestThread(AdblockPlus::JsEnginePtr jsEngine, AdblockPlus::JsValueList& arguments)
         : jsEngine(jsEngine), url(arguments[0]->AsString())
     {
       if (!url.length())
         throw std::runtime_error("Invalid string passed as first argument to GET");
 
       {
         AdblockPlus::JsValuePtr headersObj = arguments[1];
         if (!headersObj->IsObject())
           throw std::runtime_error("Second argument to GET must be an object");
 
         std::vector<std::string> properties = headersObj->GetOwnPropertyNames();
         for (std::vector<std::string>::iterator it = properties.begin();
             it != properties.end(); ++it)
         {
           std::string header = *it;
           std::string headerValue = headersObj->GetProperty(header)->AsString();
           if (header.length() && headerValue.length())
             headers.push_back(std::pair<std::string, std::string>(header, headerValue));
         }
       }
 
       callback = arguments[2];
       if (!callback->IsFunction())
         throw std::runtime_error("Third argument to GET must be a function");
     }
 
     void Run()
     {
-      AdblockPlus::ServerResponse result = jsEngine.GetWebRequest()->GET(url, headers);
+      AdblockPlus::ServerResponse result = jsEngine->GetWebRequest()->GET(url, headers);
 
       AdblockPlus::JsEngine::Context context(jsEngine);
 
-      AdblockPlus::JsValuePtr resultObject = jsEngine.NewObject();
+      AdblockPlus::JsValuePtr resultObject = jsEngine->NewObject();
       resultObject->SetProperty("status", result.status);
       resultObject->SetProperty("responseStatus", result.responseStatus);
       resultObject->SetProperty("responseText", result.responseText);
 
-      AdblockPlus::JsValuePtr headersObject = jsEngine.NewObject();
+      AdblockPlus::JsValuePtr headersObject = jsEngine->NewObject();
       for (AdblockPlus::HeaderList::iterator it = result.responseHeaders.begin();
         it != result.responseHeaders.end(); ++it)
       {
         headersObject->SetProperty(it->first, it->second);
       }
       resultObject->SetProperty("responseHeaders", headersObject);
 
       AdblockPlus::JsValueList params;
       params.push_back(resultObject);
       callback->Call(params);
       delete this;
     }
 
   private:
-    AdblockPlus::JsEngine& jsEngine;
+    AdblockPlus::JsEnginePtr jsEngine;
     std::string url;
     AdblockPlus::HeaderList headers;
     AdblockPlus::JsValuePtr callback;
   };
 
   v8::Handle<v8::Value> GETCallback(const v8::Arguments& arguments)
   {
     WebRequestThread* thread;
     try
     {
-      AdblockPlus::JsEngine& jsEngine = AdblockPlus::JsEngine::FromArguments(arguments);
-      AdblockPlus::JsValueList converted = jsEngine.ConvertArguments(arguments);
+      AdblockPlus::JsEnginePtr jsEngine = AdblockPlus::JsEngine::FromArguments(arguments);
+      AdblockPlus::JsValueList converted = jsEngine->ConvertArguments(arguments);
       if (converted.size() != 3u)
         throw std::runtime_error("GET requires exactly 3 arguments");
       thread = new WebRequestThread(jsEngine, converted);
     }
     catch (const std::exception& e)
     {
       return v8::ThrowException(v8::String::New(e.what()));
     }
     thread->Start();
     return v8::Undefined();
   }
 }
 
 AdblockPlus::JsValuePtr AdblockPlus::WebRequestJsObject::Setup(
-    AdblockPlus::JsEngine& jsEngine, AdblockPlus::JsValuePtr obj)
+    AdblockPlus::JsEnginePtr jsEngine, AdblockPlus::JsValuePtr obj)
 {
-  obj->SetProperty("GET", jsEngine.NewCallback(::GETCallback));
+  obj->SetProperty("GET", jsEngine->NewCallback(::GETCallback));
   return obj;
 }