Bug 1751182 [wpt PR 32471] - Legacy fallback - make sure that we walk far enough...

Bug 1751182 [wpt PR 32471] - Legacy fallback - make sure that we walk far enough up the ancestry., a=testonly

Automatic update from web-platform-tests
Legacy fallback - make sure that we walk far enough up the ancestry.

We cannot stop looking for a legacy fallback root, just because we've
found something that was marked earlier. It may be that an ancestor has
become a fragmentation context root since last time.

Add two crash tests. The first one being more true to the original
fuzzer test, while the other one is simplified (note that the DCHECK
failure happens somewhere else for this one).

Bug: 1288769
Change-Id: I979774cd57bb5811d02268f5a073ae44bae2d175
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/3404079
Reviewed-by: Rune Lillesveen <futhark@chromium.org>
Commit-Queue: Morten Stenshorne <mstensho@chromium.org>
Cr-Commit-Position: refs/heads/main@{#961424}

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wpt-commits: 1686461fff6811540703ee89e4ebe167c2f22176
wpt-pr: 32471