Reproduction steps:
1. Create a new project;
2. Create an Empty GameObject;
3. Add the component 'Particle System';

Actual result: Particle System material is not set to 'Default-Particle'. Instead of the default material, it shows pink squares.
Expected result: Particle System material should be set to 'Default-Particle', when Particle System is created.

Workaround: When Particle System is created like GameObject, the material is set to default. If Particle System is added like a component, the material is not set to default.

Reproduced with: 5.5.0a1, 5.5.0f3, 5.6.0a6
Not reproducible: 5.2.5f1, 5.3.6p4, 5.4.3f1
Regression introduced in 5.5.0a1