Cleaup subframes used in wpt/html/user-activation/*.html.

Change-Id: I4a7dae4534339ec2f203efa3860d5b8a9e5e9ba4
TBR: lanwei@chromium.org
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1677127
Commit-Queue: Mustaq Ahmed <mustaq@chromium.org>
Reviewed-by: Mustaq Ahmed <mustaq@chromium.org>
Cr-Commit-Position: refs/heads/master@{#672262}
8 files changed