emberjs/ember.js — pull request #4488 by rjackson (2014-03-09 22:12:20+00:00)
Title: Enable ember-debug to be loaded for non-prod builds.

The issue is that ember-debug has moved to an ES6 package and even though it
exists in the build output, it is never required so the global
`Ember` object is never extended.

This is a short-term fix, but the longer term solution is to remove the
`ember-debug` package altogether (in favor of a better build process).