fix(common.js): Error if parents[i] is undefined

[AlexJuarez]

hasOwnProperty still would throw an error if parents[i] was undefined.

[eddiemonge]

What case would parents[i] be undefined since var i in parents?

[AlexJuarez]

The parents array can be populated with undefined, right now I'm working on a app that im switching from ember router to angular ui router, and the ember router pushes undefined into the array.

[eddiemonge]

That sounds like a bug that needs to be fixed there but having the check here isn't bad. The check itself could be improved though. I think it should be something like parents[i] && !parents[i].params.

[AlexJuarez]

Changing this line allows both routers to co-exist

[AlexJuarez]

What about typeof parents[i] === 'undefined' || !parents[i].params

[AlexJuarez]

I would still like to get this fix in, even though its low priority.

[christopherthielen]

I'm ok with merging this in if we get a unit test, but ...

Changing this line allows both routers to co-exist

...is obviously not a goal of this project

[christopherthielen]

Whoops, looks like #2478 was an exact dupe of this one.