function incrementStoreStates(storeStates, storeIds) {
	  return storeStates.withMutations(function (map) {
	    storeIds.forEach(function (id) {
	      var nextId = map.has(id) ? map.get(id) + 1 : 1;
	      map.set(id, nextId);
	    });
	  });
	}
@param {Immutable.Map} storeStates
@param {Array} storeIds
@return {Immutable.Map}