Samle::mouse: fix wrong assert

Change-Id: Ifa17d524f4505514ed02716214e408fdda3ac3e8
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/227641
Reviewed-by: Hal Canary <halcanary@google.com>
Reviewed-by: Ben Wagner <bungeman@google.com>
Commit-Queue: Hal Canary <halcanary@google.com>
1 file changed