Changing the "Update Mode" property of an Animator component does not mark the scene as modified and is not saved when using File > Save Scene.

Steps to reproduce:
1. Download attached project and open scene "Scene".
2. Select "Cube" game object and change it's animator's Update Mode.
3. Save scene and reopen it.
4. Update Mode value's change was not saved.

Workarounds - if it is not the only change in the scene the change is saved.

Reproduced with - 5.4.0b1 (3137382c8e08), 5.3.1p1, 5.2.3p2