anchor.diff:     * Initialize a newly created implements clause.
      */
     ImplementsClauseImpl(this.implementsKeyword, List<TypeName> interfaces) {
  -    _interfaces = new NodeList<TypeName>(this, interfaces);
  +    _interfaces = new NodeListImpl<TypeName>(this, interfaces);
     }
   
     @override
  
positive.code:   NormalFormalParameterImpl(
        Comment comment, List<Annotation> metadata, SimpleIdentifier identifier) {
      _comment = _becomeParentOf(comment);
      _metadata = new NodeList<Annotation>(this, metadata);
      _identifier = _becomeParentOf(identifier);
    }
  
  
negative.code:    * Initialize a newly created prefixed identifier.
     */
    LibraryIdentifierImpl(List<SimpleIdentifier> components) {
      _components = new NodeListImpl<SimpleIdentifier>(this, components);
    }
  
    @override
  