Add back in min/max check on fuzzer range

BUG=skia:

GOLD_TRYBOT_URL= https://gold.skia.org/search?issue=4798

Change-Id: Ia93b4eeea82dd04f0c6bd287f61d26086a0aa740
Reviewed-on: https://skia-review.googlesource.com/4798
Reviewed-by: Kevin Lubick <kjlubick@google.com>
Commit-Queue: Kevin Lubick <kjlubick@google.com>