anchor.diff:    scanTimer.start();
     // TODO(sigmund): is there a way to scan from a random-access-file without
     // first converting to String?
  -  var scanner = new _Scanner(source.contents.data);
  -  var token = scanner.tokenize();
  +  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;
   }
  
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: 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/fasta/scanner.dart';
  import 'package:front_end/src/scanner/token.dart';
  import 'package:package_config/discovery.dart';
  import 'package:path/path.dart' as path;
  