anchor.diff:  }
   
   const dillId = const DataId("dill");
  +const updatedDillId = const DataId("udill");
  +const globalDataId = const DataId("gdata");
   const jsId = const DataId("js");
   const txtId = const DataId("txt");
   
  
positive.code:   }
  }
  
  // Step that invokes dart2js on the main module by providing the .dill files of
  // all transitive modules as inputs.
  class CompileFromDillStep implements IOModularStep {
    @override
    List<DataId> get resultData => const [jsId];
  
    @override
    bool get needsSources => false;
  
negative.code:   @override
    Future<void> execute(
        Module module, Uri root, ModuleDataToRelativeUri toUri) async {
      if (_options.verbose) print("step: dart2js global analysis on $module");
      Set<Module> transitiveDependencies = computeTransitiveDependencies(module);
      Iterable<String> dillDependencies =
          transitiveDependencies.map((m) => '${toUri(m, dillId)}');
  