Temporary removal of animations

I am attempting to add web animation support my animation library Artifact:

   https://bitbucket.org/0x0000/artifact

The approach if the library is to have the user only specify how they want
to change the dom. It is then up to the library to compute a animation from
the current dome state to the final state. This is similar in nature to CSS
transitions but more flexible and also supports layout changes.

A requirement of the library is that I can remove the effects of a running
animation, inspect an element's styles, and then restart the animation
where it left off. This has proven difficult with the web animation api as
it is implemented in chrome 39. Do do so I have to save the
player.currentTime, cancel the animation, and restart it and
set currentTime. This is ok but does not work reliably sometimes things
like element.getBoundingClientRect( ) don't reflect the changes due to
canceling the animation. Once this promise API is implemented will that
resolve this issue?

Even if the promises api can solve the issue, what I would really like is
an api to just put the animation on hold and force a recompute style
serially. I would then like to restart the animation. I would like this to
not cause any for the promises for the animation to resolve.

-Jonathan