In alpha36, a requestAnimationFrame's callback correctly gets the timestamp argument:
http://plnkr.co/edit/6ZkphwlO7hUKpoLrBDJw?p=preview

In alpha37, the rAF callback does not get the timestamp argument:
http://plnkr.co/edit/H9bYRx7gDivc5qxkdVB1?p=preview

This causes javascript animations to fail.