anchor.diff:    String _content;
     String _contentHash;
     LineInfo _lineInfo;
  +  Set<String> _definedClassMemberNames;
     Set<String> _definedTopLevelNames;
  -  Set<String> _definedClassMemberNames;
     Set<String> _referencedNames;
     Set<String> _subtypedNames;
     String _unlinkedKey;
  +  AnalysisDriverUnlinkedUnit _driverUnlinkedUnit;
     UnlinkedUnit _unlinked;
     List<int> _apiSignature;
   
  
positive.code:   /**
     * The external names referenced by the file.
     */
    Set<String> get referencedNames => _referencedNames;
  
    /**
     * The names which are used in `extends`, `with` or `implements` clauses in
     * the file. Import prefixes and type arguments are not included.
     */
    Set<String> get subtypedNames => _subtypedNames;
  
    @visibleForTesting
    FileStateTestView get test => new FileStateTestView(this);
  
negative.code:   /**
     * The class member names defined by the file.
     */
    Set<String> get definedClassMemberNames {
      return _definedClassMemberNames ??=
          _driverUnlinkedUnit.definedClassMemberNames.toSet();
    }
  
    /**
     * The top-level names defined by the file.
     */
    Set<String> get definedTopLevelNames {
      return _definedTopLevelNames ??=
          _driverUnlinkedUnit.definedTopLevelNames.toSet();
    }
  
    /**
     * Return the set of all directly referenced files - imported, exported or
  