Fix styling of shortcuts modal

## What does this MR do?

Fixes some weird height issue in the shortcuts modal.

## Screenshots (if relevant)

### Before

![Screen_Shot_2016-09-07_at_15.13.09](/uploads/5c4d7716e355794c8aa9764e0fa53f4e/Screen_Shot_2016-09-07_at_15.13.09.png)

### After

![Screen_Shot_2016-09-07_at_15.12.57](/uploads/6f5c145963b4b89910be44b6b254e117/Screen_Shot_2016-09-07_at_15.12.57.png)

See merge request !6244