emberjs/ember.js — pull request #9720 by oneeman (2014-11-26 01:37:17+00:00)
Title: Replace listenersDiff and listenersUnion with accumulateListeners

I noticed that `listenersDiff` and `listenersUnion` are doing the same thing, except that the latter wasn't returning a value. So I replaced them with a single function `accumulateListeners` and updated their usages. I also think the name more accurately reflects what they do (listenersDiff was really doing a union and then returning the diff). I realize 'accumulateListeners' is a mouthful, so I'd welcome better names for it. I considered `mergeListeners`, but it seems less accurate.

Another, trivial, change was changing a parameter `cb` to `callback`, matching the JSDoc.