use nothingToDraw more often

Bug: skia:
Change-Id: Ifafd8d90649f5aeb020335f46496a828dffac98e
Reviewed-on: https://skia-review.googlesource.com/149481
Auto-Submit: Mike Reed <reed@google.com>
Commit-Queue: Brian Salomon <bsalomon@google.com>
Reviewed-by: Brian Salomon <bsalomon@google.com>
1 file changed