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

src/JsValue.cpp

Index: src/JsValue.cpp
===================================================================
--- a/src/JsValue.cpp
+++ b/src/JsValue.cpp
@@ -12,26 +12,26 @@ namespace
   }
 
   v8::Local<v8::String> toV8String(const std::string& str)
   {
     return v8::String::New(str.c_str(), str.length());
   }
 }
 
-AdblockPlus::JsValue::JsValue(AdblockPlus::JsEngine& jsEngine,
+AdblockPlus::JsValue::JsValue(AdblockPlus::JsEnginePtr jsEngine,
       v8::Handle<v8::Value> value)
     : jsEngine(jsEngine),
-      value(v8::Persistent<v8::Value>::New(jsEngine.isolate, value))
+      value(v8::Persistent<v8::Value>::New(jsEngine->isolate, value))
 {
 }
 
 AdblockPlus::JsValue::~JsValue()
 {
-  value.Dispose(jsEngine.isolate);
+  value.Dispose(jsEngine->isolate);
 }
 
 bool AdblockPlus::JsValue::IsUndefined() const
 {
   const JsEngine::Context context(jsEngine);
   return value->IsUndefined();
 }
 
@@ -187,17 +187,17 @@ AdblockPlus::JsValuePtr AdblockPlus::JsV
     AdblockPlus::JsValuePtr thisPtr) const
 {
   if (!IsFunction())
     throw new std::runtime_error("Attempting to call a non-function");
 
   const JsEngine::Context context(jsEngine);
 
   if (!thisPtr)
-    thisPtr = JsValuePtr(new JsValue(jsEngine, jsEngine.context->Global()));
+    thisPtr = JsValuePtr(new JsValue(jsEngine, jsEngine->context->Global()));
   if (!thisPtr->IsObject())
     throw new std::runtime_error("`this` pointer has to be an object");
   v8::Persistent<v8::Object> thisObj = v8::Persistent<v8::Object>::Cast(thisPtr->value);
 
   size_t argc = params.size();
   v8::Handle<v8::Value>* argv = new v8::Handle<v8::Value>[argc];
   for (size_t i = 0; i < argc; ++i)
     argv[i] = params[i]->value;