`.trigger()` and array-like arguments

[timmywil]

Ported from http://bugs.jquery.com/ticket/14481

Something like...

"Note: When triggering with a plain object argument that is not "array-like" (as in a jQuery instance or an arguments object), but still contains a length property, pass the object in an array (e.g. [ { length: 1 } ])"

[msmuenchen]

Thanks for porting that one over. If I may ask, why is that necessary at all?

[arthurvr]

PR gh-716.