anchor.diff:      ..chaseDependencies = true
       ..target = target;
   
  +  var inputs = [Uri.parse('dart:core')];
  +  if (forFlutter && !forFlutterRelease) {
  +    inputs.add(Uri.parse('dart:vmservice_sky'));
  +  }
     var result = await generateKernel(
         new ProcessedOptions(
             options,
             // TODO(sigmund): pass all sdk libraries needed here, and make this
             // hermetic.
             false,
  -          [Uri.parse('dart:core')]),
  +          inputs),
         buildSummary: true,
         buildProgram: true);
     new File.fromUri(outlineOutput).writeAsBytesSync(result.summary);
  
positive.code:       _writeSync(uiLibraryOut, readInputFile(file.path));
      }
      locations['ui'] = 'ui/ui.dart';
    }
  }
  
  
negative.code:   exit(1);
  }
  
  const validModes = const ['vm', 'dart2js', 'flutter', 'flutter_release'];
  String mode;
  bool get forVm => mode == 'vm';
  bool get forFlutter => mode == 'flutter' || mode == 'flutter_release';
  bool get forFlutterRelease => mode == 'flutter_release';
  bool get forDart2js => mode == 'dart2js';
  
  Future _main(List<String> argv) async {
  