wpt-import: TBR current ecosystem infra sheriff

Bug: 755753
Change-Id: I12829ec0a83608219225a799d54609e3b1007d6c
Reviewed-on: https://chromium-review.googlesource.com/729639
Reviewed-by: Robert Ma <robertma@chromium.org>
Commit-Queue: Quinten Yearsley <qyearsley@chromium.org>
Cr-Commit-Position: refs/heads/master@{#510955}