Reproduction Steps:
1. Open the attached project (in Unity 5.3.X or later)
2. Open Scene1
3. Select Particle System in Hierarchy
4. Open Animation Window
5. Notice the "Particle System.Inital Module.start Size.scalar (Missing!)"

Expected Behavior: Updating Unity from 5.2.X to 5.3.X should not change Particle System.

Actual Behavior: After updating Unity from 5.2.X to 5.3.X Particle System Animation property name changed to missing.

Reproduced on: 5.3.0f4, 5.3.2p2, 5.4.0b3

Not Reproduced on: 5.2.4f1