This CL moves third_party/WebKit/LayoutTests to
third_party/blink/web_tests.

NOTRY=true
NOAUTOREVERT=true
NOPRESUBMIT=true
NOTREECHECKS=true
TBR=robertma@chromium.org

Bug: 843412
Change-Id: Ibb588b93d1579bcd1cb68df0a50efd8653f8724f
Reviewed-on: https://chromium-review.googlesource.com/c/1328627Reviewed-by: Kent Tamura <tkent@chromium.org>
Commit-Queue: Kent Tamura <tkent@chromium.org>
Cr-Commit-Position: refs/heads/master@{#610740}