From johnjbar...@chromium.org on May 08, 2012 19:23:24
Two tests fail, they are now skipped and will need be re-instated when this issue is fixed:

http://code.google.com/p/traceur-compiler/source/detail?r=671339c959178f3d12f584dbdb2a2375b80ab2cc

+ for that.
What is the hack to get able to extend DOM classes? Is it a substitution of prototype, like so:

class CustomElement extends HTMLDivElement{
     constructor(){
        var self = document.createElement('div');
        self.__proto__ = this.__proto__;
        return self;
    }

    customMethod(){
        //`this` here is the div element
    }
}

?

That is what we used to do.

The new way is based on Symbol.create and I have an old branch for that. It has some severe performance issues so I never finished that work. https://github.com/arv/traceur-compiler/tree/new-new-behavior

Symbol.create has been removed from the spec but there is the [[CreateAction]] which is similar enough.

For anyone else who comes here in search of extending Error, I believe this issue has relevance (according to @arv: https://groups.google.com/d/msg/traceur-compiler-discuss/4BqJcCuQNPQ/TPsh8SjQ2WMJ).