feat($rootScope): stopDescent method added to broadcast event

[joshrtay]

Add stopDescent to event object.

stopDescent - {function=}: calling stopDescent function will cancel further event propagation to children (available only for events that were $broadcasted-ed).

[pkozlowski-opensource]

@joshrtay what is a motivation / use case for this PR? It is missing documentation so it is hard to see what you are trying to achieve here. Did you discuss your use case on the mailing list?

[joshrtay]

this is essentially the equivalent of stopPropogation for broadcasted events.

i'm working on nested views and i would like the ability to listen for the routeChangeSuccess event on a scope, stop the event's propogation to children scopes and then rebroadcast the event on that scope after doing some asynchronous work.

[joshrtay]

maybe the method should be called stopPropagation instead.