Curves don't show by default the negative axis.

Repro steps:
1. Open ParticleCurves scene from attached project
2. Select Particle System
3. Enable Velocity over lifetime module and switch the input to curves
4. Observe how the curves don't show negative values
5. Deselect and select the Particle System again.
6. Notice how the curves show negative values.

Expected outcome: to always see negative curve values when it's possible to enter negative values.

Notes: Regression, works in 5.3.1f1