For each non-abstract non-declared (i.e. inherited from supertypes) method in
an interface we generate its static form to the TImpl, which calls the TImpl
method from the corresponding supertype.
The accidental override tests changed because we're now trying to generate the
delegate for the super method, not knowing that it will clash with the declared
method
#KT-2888 Fixed
#KT-5393 Fixed
