code: function executeDispatchesInOrderStopAtTrueImpl(event) {
    var dispatchListeners = event._dispatchListeners;
    var dispatchIDs = event._dispatchIDs;
    if ("production" !== "development") {
      validateEventDispatches(event);
    }
    if (Array.isArray(dispatchListeners)) {
      for (var i = 0; i < dispatchListeners.length; i++) {
        if (event.isPropagationStopped()) {
          break;
        }
        // Listeners and IDs are two parallel arrays that are always in sync.
        if (dispatchListeners[i](event, dispatchIDs[i])) {
          return dispatchIDs[i];
        }
      }
    } else if (dispatchListeners) {
      if (dispatchListeners(event, dispatchIDs)) {
        return dispatchIDs;
      }
    }
    return null;
  }
docs: Standard/simple iteration through an event's collected dispatches, but stops
  at the first dispatch execution returning true, and returns that id.
  
  @return id of the first dispatch execution who's listener returns true, or
  null if no listener returned true.