anchor.diff:  import 'package:kernel/analyzer/loader.dart';
   import 'package:kernel/kernel.dart';
   import 'package:package_config/discovery.dart';
  +
  +import 'package:front_end/src/scanner/reader.dart';
  +import 'package:front_end/src/scanner/scanner.dart';
  +import 'package:front_end/src/scanner/token.dart';
   
   /// Cumulative total number of chars scanned.
   int scanTotalChars = 0;
  
positive.code: import 'dart:io' show exit, stderr;
  
  import 'package:analyzer/dart/ast/ast.dart';
  import 'package:analyzer/dart/ast/token.dart';
  import 'package:analyzer/error/listener.dart';
  import 'package:analyzer/file_system/file_system.dart' show ResourceUriResolver;
  import 'package:analyzer/file_system/physical_file_system.dart'
      show PhysicalResourceProvider;
  import 'package:analyzer/source/package_map_resolver.dart';
  import 'package:analyzer/src/context/builder.dart';
  import 'package:analyzer/src/dart/scanner/reader.dart';
  import 'package:analyzer/src/dart/scanner/scanner.dart';
  import 'package:analyzer/src/dart/sdk/sdk.dart' show FolderBasedDartSdk;
  import 'package:analyzer/src/generated/parser.dart';
  import 'package:analyzer/src/generated/source.dart';
  
negative.code:   scanTotalChars += contents.length;
    // TODO(sigmund): is there a way to scan from a random-access-file without
    // first converting to String?
    var scanner = new _Scanner(contents);
    var token = scanner.tokenize();
    scanTimer.stop();
    return token;
  }
  
  class _Scanner extends Scanner {
    _Scanner(String contents) : super(new CharSequenceReader(contents)) {
      preserveComments = false;
    }
  
    @override
    void reportError(errorCode, int offset, List<Object> arguments) {
      // ignore errors.
    }
  }
  
  /// Report that metric [name] took [time] micro-seconds to process
  