How to reproduce:
1. Download project "ParticlesIssue.zip" and open in Unity
2. Enter "bug" scene
3. Select Particle System and set Start Rotation to 999999999999
-- Particle system disappears from the scene

Expected result: Degrees of rotation should be from 0 to 360 and when setting a high number, particles shouldn't disappear
Actual result: Particle system disappear from the scene

Regression first introduced in: 5.6.0b1
Reproducible with: 5.6.4p4, 2017.1.2p3, 2017.2.1p1, 2017.3.0f3, 2018.1.0b1
Not reproducible with: 5.5.6f1

RichardK note: in 5.5, the UI value is allowed to be really high, but the particles don't disappear. They act like fmod(rotation, 2*pi).