Steps to reproduce:

1. Open the attached project.
2. Go to 'Build settings' and set it to iOS platform.
3. In the 'Hierarchy' window, select 'Directional Light'.
4. In the 'Inspector' window, modify shadow strength from 1 to 0.
5. Pay attention to the shadow's in the 'Scene' window.

Adjusting the shadow strength on a realtime light causes lightmapped object to be darken. This issue is only reproducible on iOS platform, on standalone platform everything work's fine.

Reproduced on: 5.4.0f3, 5.4.0f2, 5.4.0f1, 5.4.0b25.

Didn't reproduce on: 5.3.6f1, 5.3.5f1