Screencast: https://www.youtube.com/watch?v=IBzrCmGVDkA
Browser.html: an experimental Desktop browser, based on Firefox Desktop and Firefox OS. UI is built in HTML.
Setup
Serve code via a HTTP server:
python -m SimpleHTTPServer 8000
Use a recent B2G build:
b2g --start-manifest http://localhost:8000/manifest.webapp
I recommend to use this branch for now: https://github.com/paulrouget/gecko-dev/compare/htmlrunner
Using WebIDE
The easiest way to use developer tools with Browser.html is to select the "Remote Runtime" option in WebIDE. By default you should be able to connect to the running browser at: localhost:6000.