Summary:
Changelog: Fix possible race condition inside `KeyboardAvoidingView`
Fabric has different order of events
In Fabric, `keyboardWillChangeFrame` event is fired before `onLayout`, but in Paper it is the other way around.
`KeyboardAvoidingView` depends on the order of events to function properly. Inside `_relativeKeyboardHeight` 0 is returned if `this._frame` is null.
To fix this, `bottom` margin is recalculated whenever `keyboardWillChangeFrame` or `onLayout` is triggered.
Reviewed By: shergin
Differential Revision: D22764192
fbshipit-source-id: 591ac59af4395a4d43c4e78e4fbc0ff118b292f8