Bug 1835021 [wpt PR 40218] - [scroll-animations] Avoid scroll/view-timeline-attachmen...

Bug 1835021 [wpt PR 40218] - [scroll-animations] Avoid scroll/view-timeline-attachment in WPTs, a=testonly

Automatic update from web-platform-tests
[scroll-animations] Avoid scroll/view-timeline-attachment in WPTs

These properties will be removed from the spec [1]. The new property
timeline-scope offers similar functionality.

This CL is mostly a self-explanatory migration from
*-timeline-attachment to timeline-scope, with a few exceptions:

 - The test id=timeline_ancestor_scroll_timeline_wins_on_same_element
   needed more severe adjustment, because deferred timelines are
   no longer typed (that is, a deferred timeline is not a
   scroll timeline nor a view timeline), so that test had
   to be refactored to avoid using deferred timelines.
 - A few tests in view-timeline-dynamic.html were refactored to avoid
   timeline-scope, as timeline-scope was not essential for those tests.

[1] https://github.com/w3c/csswg-drafts/issues/7759

Bug: 1446702
Change-Id: I205069b065a97928f755993f3c5f301693cc72ae
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/4565315
Reviewed-by: Mustaq Ahmed <mustaq@chromium.org>
Commit-Queue: Anders Hartvoll Ruud <andruud@chromium.org>
Cr-Commit-Position: refs/heads/main@{#1149088}

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wpt-commits: 3b4953ad7022f11d7e756404bd0c34a059431993
wpt-pr: 40218