I'd really use a Firefox version of this. Wondering how far am I from knowing how to port it myself.
Happy to add something to the readme if anyone can test and confirm.
Navigate to about:debugging, and load the manifest.json as a Temporary Add-on.
It will stay installed until you close the browser. I don't think permanently loading extensions this way will work in the normal Extensions pane until Firefox 48 is in release.
See the "Chrome compatibility" section: https://blog.mozilla.org/addons/2016/04/29/webextensions-in-...