anchor.diff:            _updateDelta = newUnit.length - oldUnit.length;
             // A Dart documentation comment change.
             if (firstPair.kind == _TokenDifferenceKind.COMMENT_DOC) {
  -            _resolveComment(oldUnit, newUnit, firstPair);
  -            logger.log('Success.');
  -            return true;
  +            bool success = _resolveComment(oldUnit, newUnit, firstPair);
  +            logger.log('Documentation comment resolved: $success');
  +            return success;
             }
             // A pure whitespace change.
             if (firstPair.kind == _TokenDifferenceKind.OFFSET) {
  
positive.code:     }
    }
  
    void _resolveComment(CompilationUnit oldUnit, CompilationUnit newUnit,
        _TokenPair firstPair) {
      Token oldToken = firstPair.oldToken;
      CommentToken precedingComments = oldToken.precedingComments;
      int offset = precedingComments.offset;
      logger.log('offset: $offset');
      Comment oldComment = _findNodeCovering(oldUnit, offset, offset);
      Comment newComment = _findNodeCovering(newUnit, offset, offset);
  
negative.code:     _updateEntry();
      // resolve references in the comment
      incrementalResolver._resolveReferences(newComment);
      // OK
      return true;
    }
  
    Token _scan(String code) {
  