Bug 1754605 [wpt PR 32788] - Reland "[LayoutNG] Add PropagateChildBreakValues flag...

Bug 1754605 [wpt PR 32788] - Reland "[LayoutNG] Add PropagateChildBreakValues flag to the ConstraintSpace", a=testonly

Automatic update from web-platform-tests
Reland "[LayoutNG] Add PropagateChildBreakValues flag to the ConstraintSpace"

This is a reland of 9ef53870dd7989885aceb015576bb7e7eb086422

The original change was reverted due to propagate_child_break_values
being uninitialized. To fix this, add an initialization to the
RareData ctr.

Original change's description:
> [LayoutNG] Add PropagateChildBreakValues flag to the ConstraintSpace
>
> This CL adds a new flag to the ConstraintSpace to propagate child break
> values (initial-break-before and previous-break-after).
>
> The flag is currently set when setting up the constraint space for
> fragmentation. However, it will also be used in future changes outside
> of the normal fragmentation pass to determine the initial-break-before
> and final-break-after for rows.
>
> The code that performs child break value propagation in
> MovePastBreakpoint() was moved to the builder, and it is run
> whenever the new flag is set to true.
>
> This fixed a bug where we failed to propagate up the break values of
> a child if there was no BFC block-offset. The reason was that we
> never called BreakBeforeChildIfNeeded() in that case. By moving the
> propagation to the builder, instead, we can ensure the break values
> are correctly propagated in this case, as well.
>
> Bug: 829028,1293291
> Change-Id: I2afd288cad99d11a1c414aca5844d7a77afef46f
> Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/3433832
> Reviewed-by: Ian Kilpatrick <ikilpatrick@chromium.org>
> Reviewed-by: Morten Stenshorne <mstensho@chromium.org>
> Commit-Queue: Alison Maher <almaher@microsoft.com>
> Cr-Commit-Position: refs/heads/main@{#969018}

Bug: 829028,1293291
Change-Id: I8f98930d65b0e9fd46e29d67c530ce72f204e2bb
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/3451309
Reviewed-by: Ian Kilpatrick <ikilpatrick@chromium.org>
Commit-Queue: Alison Maher <almaher@microsoft.com>
Cr-Commit-Position: refs/heads/main@{#969278}

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wpt-commits: cf5a0748e2733a758cf59ea01d655fb1a41d778e
wpt-pr: 32788