[LayoutNG] Remove useless optional.

This was a mistake when I was initially writing this code.

Bug: 635619
Cq-Include-Trybots: master.tryserver.chromium.linux:linux_layout_tests_layout_ng
Change-Id: Ic67f0dd0364c9a03724c626b61c56632c8fa6605
Reviewed-on: https://chromium-review.googlesource.com/600310
Reviewed-by: Koji Ishii <kojii@chromium.org>
Commit-Queue: Ian Kilpatrick <ikilpatrick@chromium.org>
Cr-Commit-Position: refs/heads/master@{#491996}
2 files changed