[web-animations-1][web-animations-2] Move iterationComposite to web-animations-2

[stephenmcgruer]

This PR moves the iterationComposite concept from the level 1 spec to the level 2 spec, as motivated in #4300

[stephenmcgruer]

Antoine, Brian - not sure what we should do with WPT tests for iterationComposite - should they be marked tentative, are we somehow else differentiating level-2 tests, or are we just leaving them all and its up to each of us to maintain what we think are the level-1-relevant tests?

[flackr]

I'd suggest marking them tentative for now, although perhaps longterm it would make sense to differentiate spec levels in wpt. I seem to recall ideas around including or referencing the test results from the spec at which point being able to differentiate spec level seems desirable. Thoughts, @foolip ?

[foolip]

If level 2 is published somewhere then they need not be tentative. You can add a link to the spec and if you need to filter based on those links perhaps we can come up with something in wpt.fyi?

[stephenmcgruer]

perhaps we can come up with something in wpt.fyi?

I think this is a great idea! I'm not sure how widespread the use of the <link rel="help" href="spec-link"> tags are, but the ability to search the whole of wpt.fyi by spec would be pretty neat, especially as we look at different levels of the same spec. Though to be fair, I'm not sure if anyone consistently keeps those separate so maybe that would limit impact...

[foolip]

Feature request is at web-platform-tests/wpt.fyi#65.

[birtles]

Looks good to me with the suggested changes.