Prerequisites:
You'll need to have Unit Editor with either Android or iOS players support installed.

Steps to repro:

1. Open attached project and 'TestScene' scene;
2. Go to Build Settings (File > Build Settings);
3. Select either Android or iOS and click Switch Platform button;
4. Observe terrain mesh rendering in Game view.

Actual result:
Massive artifacts appear on terrain's surface.See attached actual.png screnshot.
Regression introduced in Unity 2017.2.0.

Expected result:
Terrain should be rendered smoothly and consistent with Standalone platform. See attached expected.png screenshot.

Notes:
- Reproducible in 2017.3.0a5, 2017.2.0b8, 2017.2.0b7;
- Not reproducible in 2017.1.0p3, 2017.2.0b6;
- Regression since 2017.2.0b7;
- Reproducible on both Windows 10 and OSX 10.12.6;
- Reproducible fon both Android and iOS support;
- Also reproducible in Android and iOS players on devices;
- Deleting Library folder, rebaking GI or Reimporting or changing shaders on material doesn't fix artifacts.