Limit disabled dispatching fix to inserted and removed events

[ccummings]

The fix for #207 causes an infinite loop. Every time a disabled element has an event dispatched, there are 2 mutation events that are emitted (one for enabling and one for disabling the element).
When those 2 events go through dispatch 4 more mutation events are emitted (2 for each event) are emitted and so on exponentially.

This fix limits the new logic in dispatch to the two most common synthetic events a CanJS user will encounter (inserted and removed). This does mean that other synthetic events will have an issue but this bug in FF has been around for 11 years and to my knowledge has not been caused a big problem thus far.

[phillipskevin]

looks good once tests pass.