[FastBorderRadius] Move FastBorderRadius to status=experimental

TBR=nasko@chromium.org
Bug: 947715,966488

Change-Id: Ic2a11f998a315ee5dc111168db20423b5a6f17d6
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1620365
Reviewed-by: Chris Harrelson <chrishtr@chromium.org>
Reviewed-by: Mason Freed <masonfreed@chromium.org>
Commit-Queue: Chris Harrelson <chrishtr@chromium.org>
Cr-Commit-Position: refs/heads/master@{#663082}
53 files changed