[css-properties-values-api] Test var()-references w.r.t. registered lists.

R=futhark@chromium.org

Bug: 641877
Change-Id: Ia249aedc2abe7f249c28ab57732edfaf6c552f2e
Reviewed-on: https://chromium-review.googlesource.com/1172295
Reviewed-by: Rune Lillesveen <futhark@chromium.org>
Commit-Queue: Anders Ruud <andruud@chromium.org>
Cr-Commit-Position: refs/heads/master@{#582557}
1 file changed