remove unneeded noemptycheck variants of intersect

The existing intersect logic already fails if either argument is empty,
without performing any extra checks.

Change-Id: I4cc4f1e63af7efbed4e1084284c1607c104ff361
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/237142
Reviewed-by: Mike Reed <reed@google.com>
Auto-Submit: Mike Reed <reed@google.com>
Commit-Queue: Mike Reed <reed@google.com>
10 files changed