[web-animations] feedback

As an old-school actionscript animator this is really exciting to me!  This
is great work so far!  I see at least one missing piece that I thought I'd
share.

I've only been playing for 15 minutes or so but right away I wonder why all
the most common easings <http://easings.net/> are missing?  I suppose I
could manually copy the values into a cubic-bezier function but that
doesn't handle bounce or functions with overshoot like elastic and back
animations.  These are critical to getting a real-world feel to the
motion.  Am I just missing something?  Is this doable with the current
spec/polyfill?

I know this is a spec, not a high-level API but why not include the things
that will make it easy for developers to adopt?  Make it so easy to use
that people can't prefer anything else?  I'd love to build a timeline GUI
that utilizes this spec.  :)

Thanks for the consideration!
Peace!

-
Mark