always clear the looper when we're unrolling it, to not confused devices

Discovered by https://skia-review.googlesource.com/c/skia/+/119570

Bug: skia:
Change-Id: I18c13052c5eb410a46ab16e2f1015861948678af
Reviewed-on: https://skia-review.googlesource.com/121062
Reviewed-by: Florin Malita <fmalita@chromium.org>
Commit-Queue: Mike Reed <reed@google.com>
1 file changed