Thanks for the support, Robert!
However, I find this to be rather insufficient. More often than not, I'd like to open a console and poke around a bit to see what API surface is there, and while screenshots can be used for that it's cumbersome enough that I'd rather install VMs myself.
As for running a test from a Chromium code review CL in other browsers before landing, I would love that very, very much. We have a contractor working on something like that for upstream web-platform-tests, and I'm hopeful that it can also be connected directly to Chromium reviews.