Suggestion: function.this to refer to result instance of generator functions

[bergus]

Very similar to #4, solving the same issue for generator functions. There it might be even more prominent, as every generator function implicitly behaves like a constructor and has a .prototype that can be used to implement custom methods on generator instances. However, the "instance" cannot be initialised in any way from the generator function or accessed while the generator is running, even though next is a method of the instance.