title: Using $$rAF in angular app
body: <p>I'm creating a directive that animates a sequence of images (allowing to play, stop, and step). In order to get the best performance, I would like to utilize requestAnimationFrame. I noticed that there is a requestAnimationFrame service in the angular source, prefixed with double dollar signs ($$rAF) which I presume indicates that it's not for public consumption. Why is this and what downsides are there to using this service as opposed to creating one myself? </p>