Particle SubEmitters stop playing in preview when the module they are assigned to is deactivated. Any change done to these particles makes them disappear from the preview and the preview needs to be manually restarted to view them.

Repro steps:
1. Open ParticleSubEmitter scene from attached project
2. Select parent Particle System and ensure SubEmitter module is on
3. Preview particle system in scene view - observe how both green and red particles are playing.
4. Select child Red SubEmitter particle and change size while previewing in the scene view. System should update as expected.
5. Select parent Particle System and deactivate SubEmitter module.
6. Select child Red SubEmitter particle again and preview in Scene view (you'd most likely need to stop and play effect again).
7. Tweak any setting of child Red SubEmitter and observe how it disappears from the preview.

Expected outcome: SubEmitters to play as regular nested particle systems when the SubEmitter module they are assigned to is deactivated.

Notes:
- Not a regression (checked in 5.3.1f1)
- Workaround is to temporarily drag the SubEmitter out of the hierarchy or remove it from the parent SubEmitter module assignment.
- Primarily artistic issue when working on the SubEmitter separately