anchor.diff:  
   library analyzer_cli.src.bootloader;
   
  -import 'dart:io';
   import 'dart:isolate';
   
   import 'package:analyzer/file_system/physical_file_system.dart';
  
positive.code:     // All good.
      return null;
    }
  
    return 'Plugin ${plugin.name} skipped, config missing: ${missing.join(", ")}';
  }
  
  
negative.code:   /// `.analyzer_options` which is then run in a spawned isolate.
    void load() {
      List<PluginInfo> plugins = _validate(config.plugins);
      String mainSource = new Assembler(plugins).createMain();
  
      Uri uri =
          Uri.parse('data:application/dart;charset=utf-8,${Uri.encodeComponent(
          mainSource)}');
  
      // TODO(pquitslund): update once .packages are supported.
      String packageRoot =
          packageRootPath != null ? packageRootPath : './packages';
      Uri packageUri = new Uri.file(packageRoot);
  
      Isolate.spawnUri(uri, args, null /* msg */, packageRoot: packageUri);
    }
  }
  