check for no blur and exit early

Bug: skia:
Change-Id: I98c07c5fd77ec67398dd4df12fb6a24aa4ca7731
Reviewed-on: https://skia-review.googlesource.com/25567
Commit-Queue: Mike Reed <reed@google.com>
Reviewed-by: Mike Klein <mtklein@chromium.org>
Reviewed-by: Florin Malita <fmalita@chromium.org>
3 files changed