$stickyState can't access root state if no states are defined.

[christopherthielen]

Per the comments in stickyState.js:94, we need access to the internal representation of the root state. Since the mechanism used to access the root state is to decorate the .parent() state function, at least one state must be defined at config time.

I have figured out an easier way to access the root state. In $provide.decorate, the internal representation of the root state is accessible as $state.$current.