anchor.diff:      if (mode.endsWith('dbc64')) return 'ReleaseSIMDBC64';
       throw ('unknown tag in mode: $mode');
     }
  +
  +  // Print steps to reproduce build and run.
  +  void printReproductionCommand();
   }
   
   /// Concrete test runner of Dart JIT.
  
positive.code:     return runCommand(cmd, env);
    }
  
    String description;
    String generate;
    String platform;
  
negative.code:       return result;
      }
      return runCommand(['nodejs', js], env);
    }
  
    void printReproductionCommand() {
      print([dart2js, fileName, '-o', js].join(" "));
      print(['nodejs', js].join(" "));
    }
  
    String description;
  