emberjs/ember.js — pull request #4170 by rjackson (2014-01-17 02:16:04+00:00)
Title: [FEATURE ember-views-bindable-attributes]

Any properties listed in `bindableAttributes` that exist on the
`Ember.View` at the time of the first render will be bound (and observed).
However, any properties that do not exist on the View instance will not have
observers setup.

The main difference here from `attributeBindings` is the fact that the
observers are only setup when needed.