Tweak shadow sample for demos.

BUG=skia:6119

Change-Id: I5b5d4298ee21bdcc2cc9ce1fae0826cd56752c2f
Reviewed-on: https://skia-review.googlesource.com/8081
Reviewed-by: Robert Phillips <robertphillips@google.com>
Commit-Queue: Jim Van Verth <jvanverth@google.com>
1 file changed