multicol-rule-style-foo were covering exactly the same thing that
multicol-rule-foo did.

Bug: 788337
Change-Id: I4102a21194a6f99e595930054655f7aaeace432e
Reviewed-on: https://chromium-review.googlesource.com/811164
Reviewed-by: Christian Biesinger <[email protected]>
Reviewed-by: Emil A Eklund <[email protected]>
Commit-Queue: Morten Stenshorne <[email protected]>
Cr-Commit-Position: refs/heads/master@{#522123}