Version:  56.0.2901.0 canary (64-bit)
OS: OSX

What steps will reproduce the problem?
Entering text in a textarea?
Alas, no clear repro steps. It was very obvious when editing bug # (see attached video), but I can't make it happen again.

What is the expected output?
Scrollbars don't keep appearing and reappearing.

What do you see instead?
Scrollbars appear and reappear as you type, leading to very distracting layout changes.

 

Deleted: Weird layout changes.mov 265 KB

Weird layout changes.mov 265 KB Download