In PhysicsDebug window, when setting Terrain Tiles Max to 0, it behaves as if it's set to infinity

To reproduce:
1. Open Attached project
2. Open 1.unity scene
3. Open Physics Debug window
4. Enable Collision Geometry
5. Set Terrain Tiles max to 0
Expected result: No terrain tiles get debug information
Actual result: All of them do

Reproduced on:
Version 5.3.3p3 (44bf5dc38517)
Wed, 16 Mar 2016 06:55:32 GMT
Branch: 5.3/physics/editor-debug