anchor.diff:  import 'package:analyzer/src/summary/idl.dart';
   import 'package:analyzer/src/summary/link.dart';
   import 'package:analyzer/src/summary/summarize_ast.dart';
  -import 'package:front_end/src/scanner/reader.dart';
  -import 'package:front_end/src/scanner/scanner.dart';
  +import 'package:front_end/src/fasta/scanner.dart';
   import 'package:front_end/src/scanner/token.dart';
   import 'package:package_config/discovery.dart';
   import 'package:path/path.dart' as path;
  
positive.code:     return result;
    }
  }
  
  class _Scanner extends Scanner {
    _Scanner(String contents) : super.create(new CharSequenceReader(contents)) {
      preserveComments = false;
    }
  
    @override
    void reportError(errorCode, int offset, List<Object> arguments) {
      // ignore errors.
    }
  }
  
negative.code:   scanTimer.start();
    // TODO(sigmund): is there a way to scan from a random-access-file without
    // first converting to String?
    ScannerResult result =
        scanString(source.contents.data, includeComments: false);
    var token = result.tokens;
    if (result.hasErrors) {
      // Ignore errors.
      while (token is ErrorToken) {
        token = token.next;
      }
    }
    scanTimer.stop();
    return token;
  }
  