[@container] Missing impl check for scroll-state containment test
Without it, implementations without support might still pass the tests.
Change-Id: Ie9fafc526fc6d48333daf73b29e9eb392a007331
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/5984411
Reviewed-by: Daniil Sakhapov sakhapov@chromium.org
Commit-Queue: Daniil Sakhapov sakhapov@chromium.org
Auto-Submit: Rune Lillesveen futhark@chromium.org
Cr-Commit-Position: refs/heads/main@{#1377525}