UserAgent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10_12_4) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/60.0.3072.0 Safari/537.36

Steps to reproduce the problem:
1. switch to `Sources` tab within DevTools
2. select `Filesystem`
3. add files and edit
4. highlight the active line in the Codemirror editor

What is the expected behavior?
the active line witch the cursor locates should be highlighted with a different background color

What went wrong?
current line not highlighted

Did this work before? No 

Chrome version: 60.0.3072.0  Channel: canary
OS Version: OS X 10.12.4
Flash Version: Shockwave Flash 25.0 r0

here's the active line demo of Codemirror https://codemirror.net/demo/activeline.html