[web-animations-1] Added phase to Animation Timeline #4325

[JTensai]

Adding phase to Animation Timeline requires changes to multiple spec's let me know if they can be done at once in the same PR or if they need to be split into individual PR's.

I'm sure there are some places I missed that need to reference the new timeline phase. If you can think of any please comment and let me know so I can adjust the spec as needed.

[birtles]

Looking good but needs a few more tweaks.

It's fine to edit multiple specs in one PR but you might find issues linking to the phase concept from the scroll-animations-1 spec until the changes to web-animations-1 changes have landed and shepherd has been updated.

I assume this builds without link errors though, right?

[ogerchikov]

Should hold_time concept be update to include hold_phase? What if an animation is paused at timeline.currentTime of zero and 'before' phase?

[JTensai]

Should hold_time concept be update to include hold_phase? What if an animation is paused at timeline.currentTime of zero and 'before' phase?

Good catch, I will add the concept of hold_phase in the next commit.

[JTensai]

Added concept of hold phase. Ready for review again.

[birtles]

Thanks for working on this. I'm afraid I think it still needs some clarification however.

[JTensai]

I messed some things up trying to do a rebase onto a more recent master. I ended up losing the commit history of this PR, but it shouldn't matter much. Feedback has been addressed and is ready for review again :)

[birtles]

Thanks! Looks good!