update SkPathRef bounds validation

  1) print out that there is a problem and
     what that problem is
  2) switch to %g so we can see very small points
  3) return false when the bounds aren't valid

Bug: oss-fuzz:10488
Change-Id: I2a8a5611ba6459f1bd45e29a1f20510401e86f76
Reviewed-on: https://skia-review.googlesource.com/156662
Reviewed-by: Brian Salomon <bsalomon@google.com>
Commit-Queue: Brian Salomon <bsalomon@google.com>
Auto-Submit: Mike Klein <mtklein@google.com>
1 file changed