How to reproduce:

1. Open the attached project in Unity 5.3.6 and the only scene in it.
2. Observe GameObject with icon and close Unity.
3. Open same project in Unity 5.4.0 and the only scene in it.
4. Observe that GameObject gizmo icon went lost.

Expected behavior: GameObject gizmo icons are preserved after upgrading Unity.
Actual behavior: GameObject gizmo icons are lost when upgrading Unity.

Reproducible: 5.4.0b20, 5.4.0f3, 5.5.0a5
Not reproducible: 5.2.4f1, 5.3.6p2