Summary:
Replaces the keywords var with let or const in Libraries/Utilities/deepFreezeAndThrowOnMutationInDev.js
- [x] Check npm run flow
- [x] Check npm run flow-check-ios
- [x] Check npm run flow-check-android
[GENERAL] [ENHANCEMENT] [Libraries/Utilities/deepFreezeAndThrowOnMutationInDev.js] - remove var
Pull Request resolved: https://github.com/facebook/react-native/pull/22126
Differential Revision: D12929758
Pulled By: TheSavior
fbshipit-source-id: bee9dfb463d197458cb218f39274af5a4d16ce1f