need ancestorChainHasListenerOfType(type) to avoid malloc during event dispatch
Certain events could benifit from a function to check if any ancestor has a listener of a specific type.
Such events include:
and DOM Mutation events
This would allow us to trade a treewalk for a malloc. The treewalk is likely to be less expensive.
This would also require us to re-work how event listeners are stored. Using a HashMap<AtomicString, Vector<EventListenter> > would be required instead, to allow O(1) lookup of events based on type.
*** This bug has been marked as a duplicate of 16447 ***