How can the omnibox suggestions be styled in Firefox?

I built an extension for Chrome, which I want to use in Firefox. In chrome one can style suggestions using XML-syntax.

Screenshot from Chrome: Example of how the styling looks in chrome

I couldn’t find anything for Firefox and was wondering whether it was possible, and if so, how? If it’s not possible, are there plans to implement this?

I found these three documentation pages and the omnibox extension example.