I haven't tested, but I think that, due to the way exports work, it is necessary to re-export overridden methods.

My understand is that exporting really creates an alias:
```
Base.prototype.mangledMethod = function () { /* implementation */ };

// export then does
Base.prototype.exportedMethod = Base.prototype.mangledMethod
```
In this case, calling `exportedMethod` on an instance of a child class will actually give you the base class's implementation since it's the only method of that name in the instance's prototype chain.

Corrections welcome.