TransformPositionArea() incorrectly assumed two-value input
Crashed when input was not a pair, but assumed it would be.
For logical values like position-area:start, we can store the value as
a single keyword, but the flip-block version of it needs to be two
separate values.
position-area might be represented as a single keyword depending on
which it is, but it's irrelevant whether the non-flipped value was a
single keyword or two keywords. For simplicity keep identical values.
Bug: 380321441
Change-Id: I29b91e7cc6dd7bea286f11475382117afb872377
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/6063638
Reviewed-by: Anders Hartvoll Ruud andruud@chromium.org
Commit-Queue: Rune Lillesveen futhark@chromium.org
Cr-Commit-Position: refs/heads/main@{#1390298}