Summary:
Issue Fix: #13485
Yet another race condition that was found by XCode's Thread Sanitizer.
Happens because wasBatchActive is read/write from multiple threads at the same time
- opened UIExplorer and see it works
- npm run test pass
- tested on own project as well
Signed CLA
Closes https://github.com/facebook/react-native/pull/13505
Differential Revision: D4906096
Pulled By: javache
fbshipit-source-id: 5d4329aafcfe9491ce0188fa1e2dd71e09b31031