feat(jqLite): support isDefaultPrevented for triggerHandler dummies

[shahata]

triggerHandler sends dummy events to an element, but although the event includes the preventDefault method, there is no way to see if it was called for the event. This is sometimes important when testing directives that use preventDefault

[mary-poppins]

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[shahata]

This is just a simple patch to solve one particular use case that was bothering me with testing some directive. I think there are many other use cases this does not solve. For example, I might want to trigger a keydown event handler and have event.shiftKey = true. I think the best way to address this is to have a jqLite "extra" method that ppl can invoke with their own mocked event in tests instead of calling triggerHandler. Maybe simulateEvent(eventType, event[, extraParameters]) (which behaves just like triggerHandler, with the exception that the caller supplies the dummy event)... If this is something desirable, I can send a PR for this.

[IgorMinar]

lgtm

[IgorMinar]

if we went the simulateEvent route, it's likely that we'd need to provide a mock event too. your current approach is simple and gets the job done.