Support invalidation of attr()
This CL does not include attr() invalidation on pseudo elements, to be
done separately.
Bug: 40320391
Change-Id: I5d0e98d61541f9ea9186684eeb2a4637b47fde46
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/5672119
Reviewed-by: Anders Hartvoll Ruud andruud@chromium.org
Commit-Queue: Munira Tursunova moonira@google.com
Cr-Commit-Position: refs/heads/main@{#1323798}