Cast received values to <v8::Object> once type confirmed

src/sass_types/factory.cpp

@@ -60,10 +60,10 @@ namespace SassTypes
 
   Value* Factory::unwrap(v8::Local<v8::Value> obj) {
     // Todo: non-SassValue objects could easily fall under that condition, need to be more specific.
-    if (!obj->IsObject() || obj->ToObject()->InternalFieldCount() != 1) {
+    if (!obj->IsObject() || obj.As<v8::Object>()->InternalFieldCount() != 1) {
       throw std::invalid_argument("A SassValue object was expected.");
     }
 
-    return static_cast<Value*>(Nan::GetInternalFieldPointer(obj->ToObject(), 0));
+    return static_cast<Value*>(Nan::GetInternalFieldPointer(obj.As<v8::Object>(), 0));
   }
 }