[BUGFIX] Add `which` attribute to event triggered by test helper
ES6 ember-application
[BUGFIX beta] Upgrade Backburner to 0.2.0
[BUGFIX beta] Ember.onerror now uses Backburner's error handler - #3401
Revert "[BUGFIX beta] Upgrade Backburner to 0.2.0"

This reverts commit 736effe8343d9fc76447a6584895520e663bb97d.
Revert "[BUGFIX beta] Ember.onerror now uses Backburner's error handler - #3401"

This reverts commit 022c1f624e1a8e010f7134378f991f90c23ac523.