Repro steps:
1. Create a new particle system
2. Enable the Size over Lifetime module
3. Select curve
4. Observe that no curve is initialized (image attached)
5. Click on one of the curve presets
6. Curve appears

Expected outcome:
A default straight-line curve to appear in every module using a curve.

Notes:
- Regression introduced in 2017.1.0b3 (caused by the memory-saving PR)