* Fixes problem with IE8 throwing exception in commonAncestor.

[pherrymason]

Complementary fix to #3.
Previous

 for( var i in parents ) 
    parents[i] = parents[i].slice(parents[i].length - minlen);
 }

Does not iterate through elements but array methods aswell.

[Arwid]

Thanks Raúl. If you'd like, comment on http://stackoverflow.com/questions/3217147/jquery-first-parent-containing-all-children#answer-3217279 so that it's fixed there as well.

[pherrymason]

Done! Thanks ;)