anchor.diff:  const dillId = const DataId("dill");
   const updatedDillId = const DataId("udill");
   const globalDataId = const DataId("gdata");
  +const codeId = const ShardsDataId("code", 2);
  +const codeId0 = const ShardDataId(codeId, 0);
  +const codeId1 = const ShardDataId(codeId, 1);
   const jsId = const DataId("js");
   const txtId = const DataId("txt");
   
  
positive.code: /// This is a shell that runs multiple tests, one per folder under `data/`.
  import 'dart:io';
  
  import 'package:expect/expect.dart';
  import 'package:front_end/src/compute_platform_binaries_location.dart'
      show computePlatformBinariesLocation;
  
negative.code:       'package:compiler/src/dart2js.dart',
        '${toUri(module, dillId)}',
        for (String flag in flags) '--enable-experiment=$flag',
        '${Flags.dillDependencies}=${dillDependencies.join(',')}',
        '${Flags.writeData}=${toUri(module, globalDataId)}',
        '--out=${toUri(module, updatedDillId)}',
      ];
      var result =
  