emberjs/ember.js — pull request #596 by pangratz (2012-03-17 12:03:48+00:00)
Title: use Array.prototype.slice to prevent instantiating an array

as suggested by @kselden https://github.com/emberjs/ember.js/commit/2326580cda4383ee732e84a28407728fe4231bfb#commitcomment-999882

I stumbled upon this code discussion and it looks like this hasn't been adressed yet.