facebook/javelin — pull request #17 by lifeinafolder (2012-06-12 06:17:35+00:00)
Title: Optimizing JX.Keys with native Object.Keys if available

Defaulting to Object.Keys for JX.Keys if its available.

https://developer.mozilla.org/en/JavaScript/Reference/Global_Objects/Object/keys

Also, JX.Keys should typically only return enumerable keys. Currently, usage of for-in causes it to enumerate prototype chain properties too.