This macro goes at the top of every CObject-derived class like so:
class SomeClass : public CObject {
C_OBJECT(SomeClass)
public:
...
At the moment, all it does is create an override for the class_name() getter
but in the future this will be used to automatically insert member functions
into these classes.
There's very little reason to take NonnullRefPtr&& in arguments really.
You can avoid ref-count churn in the cases where ownership is transferred
from the caller to the callee, but that's a pretty unusual situation and
not worth optimizing for at this stage.
