Summary:
Refines `StyleSheet.compose` so that subtypes of `DangerouslyImpreciseStyleProp` can flow through the function call without losing their type.
This makes it so that if you supply two `ViewStyleProp` types, you will get a `ViewStyleProp` type out of it.
Reviewed By: TheSavior
Differential Revision: D8851699
fbshipit-source-id: e38e572e363a71fddf63d6b6bf5a96b3cdae5915