anchor.diff:            _mapToken(node.implementsKeyword), _cloneNodeList(node.interfaces));
   
     @override
  -  ImportDirective visitImportDirective(ImportDirective node) =>
  -      new ImportDirective(
  -          _cloneNode(node.documentationComment),
  -          _cloneNodeList(node.metadata),
  -          _mapToken(node.keyword),
  -          _cloneNode(node.uri),
  -          _cloneNodeList(node.configurations),
  -          _mapToken(node.deferredKeyword),
  -          _mapToken(node.asKeyword),
  -          _cloneNode(node.prefix),
  -          _cloneNodeList(node.combinators),
  -          _mapToken(node.semicolon));
  +  ImportDirective visitImportDirective(ImportDirective node) {
  +    ImportDirective copy = new ImportDirective(
  +        _cloneNode(node.documentationComment),
  +        _cloneNodeList(node.metadata),
  +        _mapToken(node.keyword),
  +        _cloneNode(node.uri),
  +        _cloneNodeList(node.configurations),
  +        _mapToken(node.deferredKeyword),
  +        _mapToken(node.asKeyword),
  +        _cloneNode(node.prefix),
  +        _cloneNodeList(node.combinators),
  +        _mapToken(node.semicolon));
  +    copy.element = node.element;
  +    return copy;
  +  }
   
     @override
     IndexExpression visitIndexExpression(IndexExpression node) {
  
positive.code:           _cloneNodeList(node.labels), _cloneNode(node.statement));
  
    @override
    LibraryDirective visitLibraryDirective(LibraryDirective node) =>
        new LibraryDirective(
            _cloneNode(node.documentationComment),
            _cloneNodeList(node.metadata),
            _mapToken(node.libraryKeyword),
            _cloneNode(node.name),
            _mapToken(node.semicolon));
  
    @override
    LibraryIdentifier visitLibraryIdentifier(LibraryIdentifier node) {
  
negative.code:  * mapping the old token stream to a new token stream, and preserving resolution
   * results.
   */
  @deprecated
  class IncrementalAstCloner implements AstVisitor<AstNode> {
    /**
     * The node to be replaced during the cloning process.
  