[BUGFIX canary] AutoLocation test refactor to prevent #9956/#9958 from happening again

Usually, testing that some object has a reference to another object on definition is super overkill, but since we have to mock `window.location`/`window.history` in every single test, it makes it non-obvious if they go missing or aren't what we expect them to be. This refactors things so that [we can be slightly more confident](https://github.com/jayphelps/ember.js/compare/emberjs:master...jayphelps:autolocation-regress-prevent?expand=1#diff-2d3c7c1d89f938904ace33848006d6b9R392) that these #9956/#9958 won't happen again.

Might still be overkill.. If so, feel free to close.