Remove support of NeedsManualRebaseline in layout test

Bug: 621126
Change-Id: If111cc2b1f980f79362d5e52d101e915ae7ba6ef
Reviewed-on: https://chromium-review.googlesource.com/1140927
Commit-Queue: Robert Ma <robertma@chromium.org>
Commit-Queue: Ned Nguyen <nednguyen@google.com>
Reviewed-by: Robert Ma <robertma@chromium.org>
Cr-Commit-Position: refs/heads/master@{#576200}
5 files changed