function accumulateTwoPhaseDispatchesSingle(event) {
	  if (event && event.dispatchConfig.phasedRegistrationNames) {
	    EventPluginUtils.traverseTwoPhase(event._targetInst, accumulateDirectionalDispatches, event);
	  }
	}
Collect dispatches (must be entirely collected before dispatching - see unit
tests). Lazily allocate the array to conserve memory.  We must loop through
each event and perform the traversal for each one. We cannot perform a
single traversal for the entire collection of events because each event may
have a different target.