[ReferenceTarget] Ensure setting property does invalidation, add tests
Add tree dump tests for ARIA attributes affected by reference
target that can't yet be tested in WPT.
Add WPT validating that ARIA label updates upon DOM mutations and
reference target changes.
Note that aria-owns coverage is omitted since we plan to exclude
it from reference target.
AX-Relnotes: n/a.
Bug: 346835896,353748711
Change-Id: I89f9e0c81d808ac9f1d20035660963d1d09a00aa
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/5739315
Commit-Queue: Dan Clark daniec@microsoft.com
Reviewed-by: Joey Arhar jarhar@chromium.org
Reviewed-by: Aaron Leventhal aleventhal@chromium.org
Cr-Commit-Position: refs/heads/main@{#1358498}