[IMGUI] Wind Quality dropdown text gets clipped when "Fastest" option is selected

The Wind Quality dropdown option in SpeedTree material Inspector settings gets clipped when the "Fastest" option is selected.

Steps to Reproduce:
1. Create a new Project
2. Project > Right-Click > Create > Material
3. Inspector > Shader > Nature > SpeedTree or Billboard > Wind Quality > Fastest

Actual Result:
Wind Quality value gets clipped.

Expected Result:
Wind Quality value shouldn't get clipped.

Reproducible on:
2020.1.0a8, 2019.3.0b7, 2019.3.0a3

Working Fine on:
2019.3.0a2, 2019.2.0f1

Environment :
Windows 10 and Mac 10.14.5