Didn't Firefox OS actually bring various new APIs to Firefox browser itself?
That's what I understood from their postmortem post:
"Engineering — Have a clear separation between “chrome” and web content rather than try to force the web to do things it isn’t suited to. Create device APIs using REST & WebSockets on the server side of the web stack rather than privileged JavaScript DOM APIs on the client side. Create a community curated directory of web apps on the web rather than an app store of submitted packaged apps."
https://medium.com/@bfrancis/the-story-of-firefox-os-cb5bf79...