GitLab

- Reworks tests to use PerformanceTestRunner to run code with timeline.
- Performs tests in iframe, and uses postMessage to coordinate.

Bug: chromium:1018029
Change-Id: Ie315516ddd90abe7538b485fd395d993a7a3e980
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1924712
Commit-Queue: Bill Budge <bbudge@chromium.org>
Reviewed-by: Andreas Haas <ahaas@chromium.org>
Cr-Commit-Position: refs/heads/master@{#719312}