CORBA35 — Narrowing from abstract interfaces

Summary: It has been pointed out to me that we have no way of narrowing
from abstract interfaces to non-abstract interfaces and value
classes. In Java, the helper"s narrow method has a signature of
org.omg.CORBA.Object, so it cannot take an abstract interface
type. In C++, the generated classes for abstract interfaces
have an _narrow method with the right signature (taking an
AbstractBase_ptr), but generated classes for values and regular
interfaces don"t have such a method. It seems like we would
need to add overloaded narrow methods in all these places to
make this work as envisaged in (for example) numbered paragraph
3 of section 8.3.