anchor.diff:    InheritanceManager get inheritanceManager =>
         _inheritanceManager ??= new InheritanceManager(this);
   
  +  @override
  +  LibraryCycleForLink get libraryCycleForLink => LibraryCycleForLink.instance;
  +
     /**
      * If this library already has a dependency in its dependencies table matching
      * [library], return its index.  Otherwise add a new dependency to table and
  
positive.code: 
    @override
    Element get enclosingElement => null;
  
    @override
    List<UnitElement> get units {
  
negative.code: }
  
  /**
   * An instance of [LibraryCycleForLink] represents a single library cycle
   * discovered during linking; it consists of one or more libraries in the build
   * unit being linked.
   *
   * This is a stub implementation; at the moment all libraries in the build unit
   * being linked are considered to be part of the same library cycle.  Hence
   * there is just a singleton instance of this class.
   * TODO(paulberry): replace this with a correct implementation.
   */
  class LibraryCycleForLink {
    static final LibraryCycleForLink instance = const LibraryCycleForLink._();
  
    const LibraryCycleForLink._();
  }
  
  /**
   * Element representing a library resynthesied from a summary during
   * linking.  The type parameter, [UnitElement], represents the type
   * that will be used for the compilation unit elements.
  