Use native methods rather than dojo/on.

Can't use jQuery's .trigger() because it doesn't notify listeners
registed with addEventListener().  See http://bugs.jQuery.com/ticket/11047.

Also, can't use jQuery's .on() for custom events because it erases the properties
that we added to the event object, such as evt.invalidatingProperties.
Technically, they're available through evt.originalEvent, but that's not what
users expect.  Note that if we used jQuery's .trigger() method, the custom
properties would be easily available to jQuery's on() method.

Basically, jQuery's trigger() and on() work well together, but you can't
mix and match them with native methods.
remove dependency on dojo/_base/lang.getObject()