Summary:
This PR fixes#6332
The issue is that Android Framework will return the same drawable instance for all requests if they request for the same resource. So the changes on the drawable instance will affect all users(`TextInput` in this case). The solution is very easy, call `mutate()` before change it will get a new drawable instance which make sure the change doesn't affect other users.
Closes https://github.com/facebook/react-native/pull/12493
Differential Revision: D4620034
Pulled By: astreet
fbshipit-source-id: a7b10fbc7447e01132b7ca0e1f78413796493e07