FF 24 is the latest stable. FF's docs say they added this function in FF 4.0, which was several years ago. So it's a bit more complicated than you make it out to be.

EDIT: I thought FF24 wasn't working, turns out I was confused between my Linux desktop's and Mac laptop's FF versions. Sorry!

It's actually not all that complicated.

Firefox 4 added mozRequestAnimationFrame.

Firefox 23 added the unprefixed version.

It's documented in the browser compatibility table at https://developer.mozilla.org/en-US/docs/Web/API/window.requ... (note that "moz" next to the 4.0).

That must have done the trick, it starts now, thank you for your help.

FF 24.0 ESR on FreeBSD is getting there but still some issues:

http://freebsd.1045724.n5.nabble.com/Problem-with-FireFox-24...