Reproduction steps:
1. Download project "SMALL_Physics2D_ButNo2dUsed.zip" and open in Unity
2. Open scene "Scene"
3. Select Window -> Profiler -> CPU Usage
4. Write "Physics2D" to the search field
4. Enter Play mode

Actual: Physics2D significant cost, although it is not used
Expected: Physics2D costs 0 ms

Reproduced on: 2017.3.0a3; 2017.2.0b6;
Not reproduced on: 2017.1.0p3
Regression introduced on: 2017.2.0b1

Fixed in: 2017.2.0b8