Since [`Panel`s inherit from `View`](https://github.com/mozilla-b2g/gaia/blob/3f51f302c3a0c57d8bad482ec7ee86b2819389fb/apps/clock/js/panel.js#L16), we don't need to make this selection--[the panel's top-level element is already attached to the instance as `this.element`](https://github.com/mozilla-b2g/gaia/blob/3f51f302c3a0c57d8bad482ec7ee86b2819389fb/apps/clock/js/view.js#L22).