Spec code coverage

Partial work on https://github.com/marionettejs/backbone.marionette/issues/1865

This covers another line: https://github.com/marionettejs/backbone.marionette/pull/2085

Remaining specs needed are related to: https://github.com/marionettejs/backbone.marionette/blob/minor/src/item-view.js#L30

And https://github.com/marionettejs/backbone.marionette/commit/9605abe52dec1cb1f99917952e3f7c941334e854