Fix a memory leak in Flutter (#148291) | Building Flutter

We fix a memory leak in the Flutter framework. This work was brought to you by my GitHub sponsors. Please consider becoming a monthly sponsor, too! https://github.com/sponsors/matthew-carroll ✪ Start a bounty 👉 https://flutterbountyhunters.com ✪ Say, Hi 👉 https://twitter.com/FlutterBounties