NewInstance memory leak #894

Nan::HandleScope scope;
Local FunctionTemplate tp = Nan::New(New);
tp->SetClassName(Nan::New(ClassName).ToLocalChecked());
tp->InstanceTemplate()->SetInternalFieldCount(1);
Local Function cons = tp->GetFunction();
Local Object js;
js= Nan::NewInstance(cons, argc, argv).ToLocalChecked();
args.GetReturnValue().Set(js);

Using this method, two are generated（ name is ClassName）
Causing a memory leak