Summary:
The relevant changes in the PR are to Libraries/StyleSheet/EdgeInsetsPropType.js; the rest are just removals of FlowIgnores.
The definition of the relevant types is [here](https://github.com/facebook/flow/blob/master/lib/react.js#L262-L271).
The long and short of it is that for whatever reason, Flow is unable to realize that `ReactPropsChainableTypeChecker` is a subtype of `ReactPropsCheckType` unless we assert it. Once we explicitly hint this to the typechecker, it realizes that `EdgeInsetsPropType` is indeed a valid React PropType, and stops complaining that it isn't.
Closes https://github.com/facebook/react-native/pull/16437
Differential Revision: D6109742
Pulled By: sahrens
fbshipit-source-id: e4e10720b68c912d0372d810409f389b65d7f4b1
833b27483b