Dark syntax highlighting doesn't work with diff comments

I use Monokai for my syntax highlighting theme, and the diff comments are a bit broken right now on dark themes.

Where'd my name go?

I can't see the text I'm typing!

Spooky!

What it should look like:

Example: https://gitlab.com/gitlab-com/www-gitlab-com/merge_requests/1958/diffs#note_4947471