Firefox 24 implements Map, but misses forEach on the prototype

[crfroehlich]

Despite loading the ES6 shim, FF's Map prototype is not aligned with the shim's Map prototype--at the very least, it's missing forEach.

es6 shim's defineProperties method looks correct to me, but I have not had time to properly debug it or even determine if that is the actual problem.

[ljharb]

We've already got https://github.com/paulmillr/es6-shim/blob/master/es6-shim.js#L835-L849 to patch Firefox < 23, so we'll use a similar technique to patch in forEach as well. Thanks!

Please open issues for all inconsistencies you find :-)