If Time.captureFrameRate is set to > 0 in GenLockSync class, the actual frame time is as fast as possible, ignoring the targetFrameRate value set

To reproduce:

1. Download project "TargetFrameRate_2018.2.12f1.zip" and open in Unity
2. Open "SampleScene" scene
3. Build & Run on Standalone
4. Observe results

Expected Result:

Capture Rate : 50, Target Frame Rate 50
System delta, expected: 20.000ms, actual [~20ms +- 0.2]
Unity delta, expected: 20.000ms, actual 20.000ms

Actual Result:

Capture Rate : 50, Target Frame Rate 50
System delta, expected: 20.000ms, actual [00.500 - 04.000 ms, depending on machine]
Unity delta, expected: 20.000ms, actual 20.000ms

Notes:
- This issue appears only on Windows
- This issue does not reproduce on macOS

Reproduced on Unity 2018.2.0a1, 2018.2.16f1, 2018.3.0b10 and 2019.1.0a9
Not reproduced on Unity 2018.1.9f2
Regression on Unity 2018.2.0a1