UserAgent: Mozilla/5.0 (X11; Linux x86_64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/54.0.2810.2 Safari/537.36

Steps to reproduce the problem:
1. given `font-weight: 300` css rule in styles pane
2. highlight 300
3. try to use the increase / decrease value shortcuts 

What is the expected behavior?
value increases or decreases by 1 unit or 10 units as it does with other properties like `margin`

What went wrong?
Work, it does not

- Yoda

Did this work before? No 

Chrome version: 54.0.2810.2  Channel: dev
OS Version: 
Flash Version: Shockwave Flash 22.0 r0

This is a community request: https://twitter.com/jonathanbingram/status/760606705142988802