* When overriding `Backbone.sync()`, ensure the `sync` and `error` events fire consistently.
* `Model#make()` has been removed. Use `$` instead, and be sure to grab the DOM node where necessary (using `[0]`).
* `Collection#get()` now accepts `cid`s. `Collection#getByCid()` has been removed.
* When overriding the `State` constructor, bind `change` callbacks after the default `Model` constructor is called, because the `Model` constructor no longer passes the `silent` flag when calling `set()` for the default attributes.
* In 'change' events, `options.changes` was removed. It can now be accessed through `model.changed`. Check if any attributes have changed by calling `model.hasChanged()`. Also, don't mess with `model.changed`; it persists beyond the scope of a single event.
* `options.index` is no longer be set in the `add` event callback. Use `collection.indexOf(model)` can be used to retrieve the index of a model instead.
props gcorne. fixes#23262.
git-svn-id: https://develop.svn.wordpress.org/trunk@23589 602fd350-edb4-49c9-b593-d223f7449a82
