anchor.diff:    String toString() => 'ClassScope($element)';
   }
   
  -class LibraryScope extends Scope {
  -  LibraryElement get library => element;
  -
  -  LibraryScope(LibraryElement library) : super(null, library);
  +class LibraryScope implements Scope {
  +  final LibraryElement library;
  +
  +  LibraryScope(LibraryElement this.library);
   
     Element localLookup(SourceString name) => library.find(name);
     Element lookup(SourceString name) => localLookup(name);
  -  Element lexicalLookup(SourceString name) => localLookup(name);
   
     Element add(Element newElement) {
       throw "Cannot add an element to a library scope";
     }
   
  -  String toString() => 'LibraryScope($element)';
  +  String toString() => 'LibraryScope($library)';
   }
  
positive.code:                              this.definitions, this.resolver, this.kind)
        : super(compiler) {
      variables = new VariableListElement.node(
          definitions, ElementKind.VARIABLE_LIST, resolver.scope.element);
    }
  
    SourceString visitSendSet(SendSet node) {
  
negative.code:   }
  
    visitIn(Node node, Scope nestedScope) {
      Scope oldScope = scope;
      scope = nestedScope;
      Element element = visit(node);
      scope = oldScope;
      return element;
    }
  
  