Bug 1769134 [wpt PR 34048] - Reland "Avoid unnecessary calls to paint invalidation...

Bug 1769134 [wpt PR 34048] - Reland "Avoid unnecessary calls to paint invalidation", a=testonly

Automatic update from web-platform-tests
Reland "Avoid unnecessary calls to paint invalidation"

The original patch was reverted due to a memory size regression
(crbug.com/1323173) and a test flake (crbug.com/1291090).

In the original patch, the size of an ElementAnimations increased due
to the addition of a data member with an enumerated value.  This size
increase was addressed by packing the new enumerated value and the
boolean valued data member into a bitfield.

The test flake was caused by a DCHECK failure, which in turn was the
result of a faulty assumption about when an animation can be composited.
Once a composited animation is downgraded to a main thread animation, it
cannot become a composited animation without a pending animation update.
Thus, it is possible for CheckCanStartAnimationOnCompositor to return
kNoFailure even if the animation will remain running on the main thread.

The revert of the CL, exposed several perf improvements, which showed
up as regressions due to the revert: crbug.com/1323940,
crbug.com/1323977, crbug.com/1324140, and crbug.com/1324224.

Original:
https://chromium-review.googlesource.com/c/chromium/src/+/3542797

Revert:
https://chromium-review.googlesource.com/c/chromium/src/+/3635297

Bug: 1301961
Change-Id: I1702eb5485c62a77cb2a1e740ced04a06c2f25ce
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/3644990
Reviewed-by: Robert Flack <flackr@chromium.org>
Commit-Queue: Kevin Ellis <kevers@chromium.org>
Cr-Commit-Position: refs/heads/main@{#1003894}

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wpt-commits: 244c976ed9c0c59e75fb5d235eff2f34ea665c96
wpt-pr: 34048