Bug 1567542 [wpt PR 17938] - [OT-PW] Animation integration with new CC impl, a=testonly

Bug 1567542 [wpt PR 17938] - [OT-PW] Animation integration with new CC impl, a=testonly

Automatic update from web-platform-tests
[OT-PW] Animation integration with new CC impl

This CL is for Off-thread PaintWorklet animation
integration described in this design doc:
https://docs.google.com/document/d/1a7gO6cBxsJhn53akuJuieUiXvB74vvEmFDyKww8NKdw/edit#

Right now this CL handles composited custom property animations
only, handling native properties should be simpler. Also,
right now we only support custom properties that represent
numerical values.

Here is a summary of the main changes:
A new class AnimatedPaintWorkletTracker is created and LTHI
keeps an instance of it. The new class maintains a hashmap
such that when CC animation ticks, LTHI is able to update the
custom property values for corresponding PaintWorkletInput. And
also that when LTHI needs to dispatch paint job to the worklet
thread, it is able to identify which paint worklets are dirty.

Other changes are mostly plumbing needs associated with the
above changes.

Bug: 956650
Change-Id: If27d6d21cf8fab31e0a2719d81b61cae3d4f3268
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1614120
Commit-Queue: Xida Chen <xidachen@chromium.org>
Reviewed-by: Robert Flack <flackr@chromium.org>
Reviewed-by: Emil A Eklund <eae@chromium.org>
Reviewed-by: Khushal <khushalsagar@chromium.org>
Reviewed-by: Anders Hartvoll Ruud <andruud@chromium.org>
Cr-Commit-Position: refs/heads/master@{#687049}

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wpt-commits: 31d0510ee0d8995a294a4e4365a8307607dfa474
wpt-pr: 17938