Reset Functionality doesn't work for Following Properties under Custom Font Asset
1) Default Material
2) Character Spacing
3) Character Padding

Steps to repro:
1. Create a new project
2. Project > Create > Custom Font
3. Project > Custom Font > Inspector > change Font Properties > Reset

Actual Result:
Reset Functionality doesn't work for Custom Font Asset.

Expected Result:
Properties of Custom Font Asset get reset.

Occurring on:
2020.2.0a20, 2020.1.1f1, 2019.4.0f1, 2018.4.23f1, 2017.4.40f1

Environment:
Windows10 and macOS 10.14