systemJSConstructor is not getting called when extending System.constructor and transpile with Babel

[katrotz]

Trying to extend the System.constructor in a ES2015 class syntax and transpile with Babel the SystemJSLoader is not getting invoked.

The issue is only reproducible with Babel transpiler, Traceur works fine. The discrepancy hides in the way super is implemented:

Babel: _get(Object.getPrototypeOf(SubClass.prototype), 'constructor', this).call(this); which returns the constructor of SuperClass prototype
Traceur: $traceurRuntime.superConstructor(SubClass).call(this); which returns the SuperClass

Note: Related issue on babel side: babel/babel#2048

[guybedford]

Released in 0.19.0.