ParticleSystem with the emission module disabled or an emission rate of 0 still spends time updating particles and any associated point lights.
Steps to reproduce:
1. Open attached project
2. Open "TestScene" Scene
3. Press play
4. Toggle EmissionModule active state and rate over time value with 'E' and 'R'
-Inspect "Update Lights" calls in profiler

Expected result: ParticleSystems should use very little (if any) time to update lights in the profiler when they have no active particles.
Actual result: "Update Lights" are still called constantly even when there are no active particles (emission module is disabled or emission rate is set to 0)

Note: ParticleSystems are spending time updating their particles and lights unless Stop is called

Reproduced on: 2018.1.4f1, 2018.2.1f1, 2018.3.0a6