[BUGFIX beta] Fix `Maximum call stack size exceeded` error when injecting un-lookup'd controller on controllers 

Prior to this commit, while trying to inject an un-lookup'd controller on other controllers causes redundant cycles during [buildInjections](https://github.com/emberjs/ember.js/blob/master/packages_es6/container/lib/container.js#L657) thereby resulting in `Maximum call stack size exceeded` error. 
[JS Fiddle Demonstrating the issue](http://jsfiddle.net/selvaG/bt6Gg/2/)

The case is valid for all similar type injections i.e., injecting [unresolved]controller on controlers || [unresolved]route on routes.

This PR fixes the issue.

/cc @stefanpenner