Respect strict constraint in drawEdgeAAImageSet

Bug: skia:
Change-Id: I840a4d12e9b7b09b64ef6c386714e813f75a86a7
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/201613
Commit-Queue: Michael Ludwig <michaelludwig@google.com>
Commit-Queue: Brian Salomon <bsalomon@google.com>
Auto-Submit: Michael Ludwig <michaelludwig@google.com>
Reviewed-by: Brian Salomon <bsalomon@google.com>