code: function addToCount(mChangeListeners, sPath, aCollection, iDelta) {
  		if (aCollection.$count !== undefined) {
  			setCount(mChangeListeners, sPath, aCollection, aCollection.$count + iDelta);
  		}
  	}
docs: Adds the given delta to the collection's $count if there is one.
  
  @param {object} mChangeListeners A map of change listeners by path
  @param {string} sPath The path of the collection in the cache (as used by change listeners)
  @param {array} aCollection The collection
  @param {number} iDelta The delta