Summary:
This pull requests converts `TextInput` to an ES6 class, and in the process removes its usage of `prop-types` and `NativeMethodsMixin`.
The code (and some relevant types) for the native components have been moved to `TextInputNativeComponent.js`.
The rest of the flow proptypes have been moved to `TextInputTypes.js`.
Pull Request resolved: https://github.com/facebook/react-native/pull/21885
Reviewed By: RSNara
Differential Revision: D10515754
Pulled By: TheSavior
fbshipit-source-id: 5cfb25344385904b37a49582008c2a4b46db809d
