Promises proposal for ES6

According to Rick Waldron (TC39 member) on twitter[1][2], this has just been elevated to a harmony proposal[3][4].

[1] https://twitter.com/rwaldron/status/380725837038759936

[2] https://twitter.com/rwaldron/status/380742382594953216

[3] http://wiki.ecmascript.org/doku.php?id=harmony:proposals

[4] https://mail.mozilla.org/pipermail/es-discuss/2008-August/00...