FLEDGE WPT: teach subordinate-frame to integrate with testdriver
Previously https://chromium-review.googlesource.com/c/chromium/src/+/5895659
fixed a few tests to do it by hand, but I want to do use testdriver in
a lot more tests (e.g. to do attestation), so it makes more sense to
have subordinate-frame set things up for it correctly just like it does
for our own messages.
Change-Id: I48604d1c99678fcfedf41e446ef7e16546a4c3b6
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/5905379
Reviewed-by: mmenke mmenke@chromium.org
Commit-Queue: Maks Orlovich morlovich@chromium.org
Cr-Commit-Position: refs/heads/main@{#1363240}