Summary:
Refactors `KeyboardAvoidingView` by using class syntax and fixing all Flow errors.
Note that there's still a bunch of sketchy stuff going on in this component with mutated instance variables (that are used in `render`!) and unsafe lifecycle methods. But at least now it's a little bit less painful on the eyes.
Reviewed By: TheSavior
Differential Revision: D7987443
fbshipit-source-id: f5c27a9dd383c430d9a5a9dc0b6e10e2c4fe8dd9
c017dcb0f2