Summary:
A small numerical fix for IoU for 3D boxes, fixes GH #992
* Adds a check for boxes with zero side areas (invalid boxes)
* Fixes numerical issue when two boxes have coplanar sides
Reviewed By: nikhilaravi
Differential Revision: D33195691
fbshipit-source-id: 8a34b4d1f1e5ec2edb6d54143930da44bdde0906