To reproduce:

1. Create a new project in 5.5
2. Add a Cube with a BoxCollider to a scene
3. Save the scene
4. Close Unity
5. Reopen Unity and load the project created in step 1
6. Select the cube in the scene and click the Edit Collider button in the Inspector
7. Collider handles do not appear

Expected behavior: Handle should appear when edit button is pressed

Original steps:

1. Open attached project (repro829182.zip)
2. Open scene
3. Select "hiyoko" game object
4. Try to edit Polygon collider
5. Notice that edit handle doesn't appear

Expected behavior: Handle should appear when edit button is pressed

Reproducible: 5.5.0b2, 5.5.0b3
Regression from 5.4.1f1

Issue reproduced on OSX and Windows 10