Support Firefox for Android

[1ec5]

Once #9 is complete, we should be most of the way towards Firefox for Android support. The UI would have to be ported to the NativeWindow and BrowserApp APIs (still in JavaScript, thankfully), but otherwise integration with the browser should be very straightforward.

This would be AVIM “lite”: NativeWindow provides no interface to manipulate input in the application chrome, but there isn’t much application chrome other than the URL/search bar. AVIM would still be able to provide proper support for undo/redo, WYSIWYG editors, and custom editor surfaces.

Unlike Fennec (#86), Firefox for Android doesn’t seem to expose such a complex Electrolysis interface.