[css-anchor-position] Last successful position option
Persist the last successful position option at resizeObserver time to be
used as the fallback when all position options overflow, instead of
falling back to the style without applying any of the position-try-
options.
The active-style update currently over-invalidates when we add, remove,
or modify @position-try rules as there is currently no diffing between
old and new @position-try rules within a stylesheet.
Bug: 331841274
Change-Id: I9765fb2521cdacab928e43ad235ce8fdacdd0841
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/5515131
Reviewed-by: Anders Hartvoll Ruud andruud@chromium.org
Commit-Queue: Rune Lillesveen futhark@chromium.org
Cr-Commit-Position: refs/heads/main@{#1301965}