- Add a browser test case that uses real (not mocked) CertVerifier.
- Re-generate test certificates removing the critical flag of
  CanSignHttpExchangesDraft extension, since the extension is not known to
  the OS cert verifiers.

Bug: 851778
Change-Id: Ic43319229feddcbaa0349a4f81c995011e63bc7b
Reviewed-on: https://chromium-review.googlesource.com/1116406Reviewed-by: Ryan Sleevi <rsleevi@chromium.org>
Reviewed-by: Kinuko Yasuda <kinuko@chromium.org>
Commit-Queue: Kunihiko Sakamoto <ksakamoto@chromium.org>
Cr-Commit-Position: refs/heads/master@{#571770}