RE: [css3-animations] Ability to have "adjacent" keyframes / "instantaneous" interpolations

[Tab Atkins Jr.:]
 
> The reason I call it hacky is not its lack of discoverability (though
> that's a problem), but because it relies on the author guessing at an
> appropriate epsilon to add to the keyframe time.  If they guess too large,
> it might be detectable in some cases as a small lag before the property
> starts animating again.  If they guess too small, they'll run into impl
> precision limits and might accidentally collapse it into the same time,
> which has a bad effect.  (That is, "50%" and "50.000001%"
> might be the same time, depending on impl limits.)
> 
> We generally try to avoid doing things like this, where rounding behavior
> is potentially exposed to authors.
> 
Yes, we would still want a keyword that indicates the next keyframe rule
defines, well, the next frame in the animation.

Somehow allowing multiple keyframe rules with the same selector would not
be backward-compatible and I think it should really be an explicit selector
value or function.

May not make this level but I'll add it to the bug list.