fix(jqLite): fix event.stopImmediatePropagation() so it works as expected

jqLite doesn't override the default implementation of event.stopImmediatePropagation()
and so it doesn't work as expected, i.e, it doesn't prevent the rest of the event
handlers from being executed.

Closes #4833
test(jqLite): Refactor test for isDefaultPrevent

Refactor the spec for isDefaultPrevent method so it fails if the
existing expectations aren't executed.