check for overflow in maxedgecount

Bug: 848521
Change-Id: I5d5f28bc2ceef6e7a90b87f5e8c064473c6f67a3
Reviewed-on: https://skia-review.googlesource.com/146880
Auto-Submit: Mike Reed <reed@google.com>
Commit-Queue: Herb Derby <herb@google.com>
Reviewed-by: Herb Derby <herb@google.com>
1 file changed