Steps to replicate the issue (include links if applicable):

• Visit a diff for which a visual diff can't be shown. Example: https://no.wikipedia.org/w/index.php?title=MediaWiki:Mainpage-title-loggedin&oldid=prev&diff=24375901
• Observe the icons

What happens?:

• The buttons have no icons:
  

What should have happened instead?:

• The buttons should have their normal icons.

Software version (skip for WMF-hosted wikis like Wikipedia):

Other information (browser name/version, screenshots, etc.):