Bug 1066045 - [v2.2][v2.1] Rapidly tapping record after switching from p...

...icture to camera mode will take photo instead of video
I removed this line as part of [bug 1061996](https://bugzilla.mozilla.org/show_bug.cgi?id=1061996) as it can leave the controls permanently disabled. This is because in some edge cases the mode doesn't get changed and the 'ready' event never fires. We need to rely on the 'ready' and 'busy' events only.

I'm guessing the root of the problem here is that in the mode change flow, camera is firing 'ready' too early, before the the entire process has finished. I think we need to be more careful where we fire 'ready' in `camera.js`.