Expanding "Timeline" then "Outline" dropdowns multiple times increases "Outline" drop down size even when empty.

[asabryy]

Browser bug:

A minor annoyance, every time expanding then collapsing timeline, and outline drop-downs, the outline section gets bigger and bigger and then needs to be resized

Steps to recreate (while working in a git repo):

1. Click on the "Timeline" drop-down to expand
2. Click on the "Outline" drop-down to expand
3. Click on "Timeline" to collapse drop-down
4. Click on "Outline" to collapse drop-down
5. Repeat first 4 steps

[sbatten]

duplicate #126523