Project don't work on Firefox (39)

[johnnny333]

Like title said, everything works fine under Chrome (43.0.2357.130 (64-bit)) but when i paste the SuperDevMode link into Firefox (39) it won't even compile. My system is Debian 7.
Firebug throws 1 error:
1)Error: Assertion failed

throw new Error('Assertion failed');

and one warning
1)mutating the [[Prototype]] of an object will cause your code to run very slowly; instead create the object with the correct initial [[Prototype]] value using Object.create

element.proto = definition.prototype;

So far, I've only tried changing user agent in module.xml but no results.