MD is not WM
Normalize -0 keys to +0 in Map.prototype.set and Set.prototype.add

Per http://esdiscuss.org/topic/samevaluezero-comparator-and-compatibility
Promise.cast is renamed to Promise.resolve (remove old Promise.resolve)

https://github.com/rwaldron/tc39-notes/blob/master/es6/2014-01/jan-30.md