Summary:
Looking to address a few new `FlowFixMe`s I had to do some minor refactoring of `MessageQueue`. Has the advantage of (IMO) making things clearer by removing a redundant counter and some gratuitous bitwise operations.
Previously `_callbacks` was an array of `?Function`s where even elements were failure callbacks and odd elements were successes. Each new call incremented `_callID` by one and `_callbackID` by two. I've changed this to use two arrays `_successCallbacks` and `_failureCallbacks` indexed by `callID`. That made the `_callbackID` counter unnecessary and reduced the need for computed indices.
Tested with flow and a quick play with UIExplorer.
Closes https://github.com/facebook/react-native/pull/11986
Differential Revision: D4962162
Pulled By: javache
fbshipit-source-id: 17dddfedc0cb5950dbdd9bd06fae6eb6de4c4a7d
0a55e42ef6