Ember.js app blank screen in many major browsers

Many major browsers, beyond those with known compatibility issues are failing to our our site, and I am stumped.

http://ift.tt/1OBT7NK

http://ift.tt/1ILd1pb

Notable ones are the 'Internet' browsers on Android phones, every single IE including the latest >9 releases, and the preview for Google's PageSpeed Insights.

How can we begin diagnosing this?