[Feature Request] Standalone developer tools instance

[Arteneko]

Currently, we can debug a page on the Servo project using Firefox, after tweaking a bit the dev tools to connect to a remote host.

Connecting to servo's exposed dev server from Firefox opens a developer tools window.

It'd be nice, just like we start servo using command line arguments, to be able to run a standalone dev tools instance, directly wired to said servo instance, through command line arguments, without having to pass through Firefox at all.