Fyrd/caniuse — pull request #423 by jakub-g (2014-01-20 12:17:05+00:00)
Title: Promises are available in Firefox 27+

Firefox 27 (now beta) supports Promises by default. Fx 24-26 provide experimental support (behind the flag in about:config)

https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Promise