anchor.diff:    /// computed.
     Source librarySource;
   
  -  /// A table mapping the offset of a directive to the annotations associated
  -  /// with that directive, or `null` if none of the annotations in the
  -  /// compilation unit have annotations.
  -  Map<int, List<ElementAnnotation>> annotationMap;
  -
     /// A list containing all of the top-level accessors (getters and setters)
     /// contained in this compilation unit.
     List<PropertyAccessorElement> _accessors;
  
positive.code:       TopLevelVariableElement from, TopLevelVariableElement to) {
      int index = _variables.indexOf(from);
      _variables[index] = to;
    }
  
    /// Set the annotations associated with the directive at the given [offset] to
    /// the given list of [annotations].
    void setAnnotations(int offset, List<ElementAnnotation> annotations) {
      annotationMap ??= new HashMap<int, List<ElementAnnotation>>();
      annotationMap[offset] = annotations;
    }
  
    @override
  
negative.code:     }
    }
  
    @override
    ElementImpl getChild(String identifier) {
      //
  