No SkDebugf for approximate intersection

TBR=mtklein@google.com

BUG=skia:

GOLD_TRYBOT_URL= https://gold.skia.org/search?issue=4911

Change-Id: I23bc298186f93c1a97a15d00b34f65cd72f964e7
Reviewed-on: https://skia-review.googlesource.com/4911
Reviewed-by: Yuqian Li <liyuqian@google.com>
Reviewed-by: Mike Klein <mtklein@chromium.org>
Commit-Queue: Yuqian Li <liyuqian@google.com>
Commit-Queue: Mike Klein <mtklein@chromium.org>