Now that we are writing more complex code in the effect control
linearizer, it can be helpful to stop in certain cases during
development / debugging.

Bug: 
Change-Id: Ibeafe807c43e092534509d4d9c3f84f9c20525a5
Reviewed-on: https://chromium-review.googlesource.com/584749Reviewed-by: Jaroslav Sevcik <jarin@chromium.org>
Commit-Queue: Michael Stanton <mvstanton@chromium.org>
Cr-Commit-Position: refs/heads/master@{#46869}