Fix memory leak with Animated API

[staszekscp]

Summary

While working with @react-navigation package I noticed a leak that was leaving multiple Detached <div> instances in the memory while using Animated API on web. They were never garbage collected.

After a week-long investigation I finally found the root cause for the problem. It turned out that _animatedView instance was never set to null, even after detaching the element. It turned out that this problem has already been solved in the react-native repository. But since react-native-web uses an older version of React Native it was not reflected in the vendor directory.

My suggestion is to cherry-pick this solution also to some other versions of react-native-web (to v19 and v20), since I noticed it there, too.

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[necolas]

Yeah patching this is a good idea. I don't know of a good way to keep Animated up to date given the effort to make the RN Animated available as an installable package has stalled.

[necolas]

Out in 0.21.1

[staszekscp]

Thanks for the quick reaction!