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

• Set the app theme to dark or black (do not use default/match system theme)
• View toasts

What happens?:
Toasts appear in light mode

What should have happened instead?:
Toats should respect dark and black themes

Software version (on Special:Version page; skip for WMF-hosted wikis like Wikipedia):
Tested on 8.0.1347
Other information (browser name/version, screenshots, etc.):