[spijdar]

Unless GP's objection to chromium OS is entirely because it's chromium, I don't think Firefox OS would be any better as it's essentially the same thing, Firefox running on Linux (not on bare metal)

Without writing the entire browser from scratch, I don't personally think there's much point to this. I suspect if you traced down the library/runtime requirements for Firefox and reimplemented them in a bare metal runtime, you'd end up with something remarkably complex and not much simpler than Linux + runtime in the end.

This is assuming you want a full browser capable of everything Firefox and Chromium are, which includes things like WebGL. If you cut out components, you can definitely reach a point where a bare metal browser is sensible, the question is how much are you willing to sacrifice from "web standards" and how much work are you willing to do reimplementing a kernel, TCP/IP stack, device drivers, etc...

[nine_k]

I can imagine a unikernel running a browser.

I cannot imagine a unikernel with all the drivers ready for a reasonable variety of PC hardware, unless it's able to reuse Linux or at least FreeBSD as a source of drivers.