[@container] Improve assert_implements for container-types
Use separate assertions for size, scroll-state, and style queries.
Since style queries are not detectable through CSS.supports, use
serialization of for now.
Change-Id: Ia2ebd2b19ae25af3bd7a2ad6b77133e496f0c46e
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/5979992
Reviewed-by: Anders Hartvoll Ruud andruud@chromium.org
Commit-Queue: Rune Lillesveen futhark@chromium.org
Cr-Commit-Position: refs/heads/main@{#1376840}