[LayoutNG] Update multicol FlagExpectations for LayoutNG

Two multicol tests time out flakily, but if they don't, they pass.

TBR=atotic@chromium.org,kojii@chromium.org

Cq-Include-Trybots: master.tryserver.chromium.linux:linux_layout_tests_layout_ng
Change-Id: I63f2434629f833c6d52f0a4672faa1a3be1fa8a3
Reviewed-on: https://chromium-review.googlesource.com/666619
Reviewed-by: Koji Ishii <kojii@chromium.org>
Reviewed-by: Morten Stenshorne <mstensho@opera.com>
Commit-Queue: Morten Stenshorne <mstensho@opera.com>
Cr-Commit-Position: refs/heads/master@{#501923}
1 file changed