Also attempt to exit early when iterating b's keys in shallowEqual

[jcready]

Prior conversation

[jimbolla]

Can you run some perf benchmarks just to be sure it's faster? You know that old saying about what happens when you ASSUME.

[appden]

I'm more concerned of the correctness of shallowEqual in react-redux. There are a few subtle ways it could fail right now. I think it would be best to copy shallowEqual from fbjs.

[jcready]

I agree with @appden here. For instance shallowEqual in react-redux doesn't account for NaN. If an object contained any NaN value then shallowEqual would always return false.

[timdorr]

I'm going to close this out and we can switch over to the fbjs version. It seems to cover more edge cases and might even be faster in common cases for react-redux.