Turing on SwiftShader for Layout Tests on Windows.
Added expectations for tests which will require rebaselining.

Bug: 726075
Change-Id: Ibbd12a6c45a103d97d0804f61000bbb19c2d7b02
Cq-Include-Trybots: master.tryserver.chromium.android:android_optional_gpu_tests_rel;master.tryserver.chromium.linux:linux_optional_gpu_tests_rel;master.tryserver.chromium.mac:mac_optional_gpu_tests_rel;master.tryserver.chromium.win:win_optional_gpu_tests_rel
Reviewed-on: https://chromium-review.googlesource.com/593847


Commit-Queue: Alexis Hétu <sugoi@chromium.org>
Reviewed-by: Kenneth Russell <kbr@chromium.org>
Cr-Commit-Position: refs/heads/master@{#494320}