anchor.diff:        /// for the class. Override that target if [reference] is a not abstract.
         /// If it's abstract, then the superclass's method will be called, so do
         /// not update the target.
  -      SelectorInfo addMember(Reference reference) {
  +      void addMember(Reference reference) {
           SelectorInfo selector = _createSelectorForTarget(reference);
           if (reference.asMember.isAbstract) {
             // Reference is abstract, do not override inherited concrete member
  
positive.code:           addMember(member.getterReference);
            if (member.hasSetter) addMember(member.setterReference!);
          } else if (member is Procedure) {
            SelectorInfo method = addMember(member.reference);
            if (_selectorMetadata[method.id].tornOff &&
                _procedureAttributeMetadata[member]!.hasTearOffUses) {
              addMember(member.tearOffReference);
            }
          }
  
negative.code:           selector.targets[info.classId] = reference;
          }
          selectorIds.add(selector.id);
        }
  
        // Add the class to its non-static members' selectors. If `info.cls` is
  