Cover frontend with js unit and/or behat tests

[PhMemmel]

Once moodle has implemented a framework for js unit testing, the frontend should be covered by js unit tests, because this activity heavily relies on js frontend.

Especially the different buttons and options in the menus depend heavily on configuration and capabilities, so they should be covered by automated tests.

Also behat tests would be possible, but might require pretty big effort to implement, because probably one would have to create a lot of custom behat steps.