Well then, they have already arrived here in Pale Moon.
Material Moon is fork of PMChrome. I would like to say thanks to Lootyhoof for providing the assets from his unfinished material theme.
It also includes dark private browsing mode:
Source code is available here:
You can also download a packaged XPI here:
If you previously installed an older version of this theme, you need to uninstall it first before installing this one.