[scroll-animations-1][web-animations-2]: Move web-animations-2 to draft spec

[kevers-google]

The scroll-animation-1 spec has dependencies on web-animations-2, which is presently an unofficial proposal draft.

We should consider splitting web-animations-2 and moving essential pieces into a full draft spec.

The required pieces are:
* Timelines
* Animations (normalization process when using a progress-based timeline)
* Setting the timeline of an animation
* Validating a CSSNumberish time
* Setting the current time of an animation
* Setting the start time of an animation
* Playing an animation
* Pausing an animation
* Canceling an animation
* Animation effect phases and states (partial: rule for when to have an inclusive endpoint).
* Iteration intervals (partial: Intrinsic iteration duration & duration: 'auto')

At present, sections specific to group effects could be split out into web-animations-3.

[birtles]

If it's only group effects that wouldn't be included. Can we just make the whole thing a FPWD?

We really need to get level 1 to CR too.

[kevers-google]

Moving all of web-animations-2 to FPWD sounds good too.