Reproduction steps:
1. Create new project
2. Create script with: void Update () { Debug.Log(System.Environment.TickCount); }
3. Run on mac editor
4. Look at console
5. Change machine time
6. Notice that tick changes together with time

7. Try again with Windows machine
8. Notice that tick doesn't change when time is changed

Expected behaviour: When device/machine/software/os time is changed - tickcount should not change.
Actual result: On iOS devices or Mac machines tickcount changes when time is changed.

Reproduced on versions: Unity 5.3.7f1, 5.3.8f2, 5.4.5p2, 5.5.3p4, 5.6.1p1, 2017.1.0b7, 2017.2.0a1

Reproduced on iMac and iPad Mini 2 iOS 10.3.1
Did not reproduce on Windows machine