anchor.diff:      }
       // TODO(jacobr): use hierarchy.isSubclassOf once we are using the
       // non-deprecated ClassHierarchy constructor.
  -    return hierarchy.getClassAsInstanceOf(clazz, _widgetClass) != null;
  +    return hierarchy.isSubclassOf(clazz, _widgetClass);
     }
   
     void _transformWidgetConstructors(Set<Library> librariesToBeTransformed,
  
positive.code: 
      // Add named parameters to all constructors.
      clazz.constructors.forEach(handleConstructor);
      hierarchy.applyChanges(<Class>[clazz]);
    }
  
    /// Transform the given [program].
  
negative.code:   /// performing a hot reload.
    void transform(Program program) {
      final List<Library> libraries = program.libraries;
  
      if (libraries.isEmpty) {
        return;
  