It doesn't use any Chrome specific features and it will work on FF, but it needs to be optimized to get buttery smooth 60fps animations. As you know, the logic for when the various browsers do layout, create layers, upload them to the GPU, etc is different, and that causes divergence rendering performance. It was hard enough to do this on Chrome, it just takes time.

We also ran into a recent difference in the way sparse JS arrays as handled. We use sparse JS arrays for some data structures, but array.splice(0) on Chrome runs much faster than FF when using this to clone a sparse array.

There's no intent to exclude Firefox, engineers are staying late in the office working on it.