anchor.diff:  
   /// Concrete test runner of Dart JIT.
   class TestRunnerJIT implements TestRunner {
  -  TestRunnerJIT(String prefix, String tag, String top, String tmp, this.env,
  +  TestRunnerJIT(String prefix, String tag, this.top, String tmp, this.env,
         this.fileName, List<String> extraFlags) {
       description = '$prefix-$tag';
       dart = '$top/out/$tag/dart';
  
positive.code:   }
  
    static String getDartSdkRevision(String top) {
      top = getTop(top);
      ProcessResult res =
          Process.runSync('git', ['--git-dir=$top/.git', 'rev-parse', 'HEAD']);
      if (debug) {
        print('\ngit rev-parse HEAD result:\n'
            '${res.exitCode}\n${res.stdout}\n');
      }
      return res.stdout;
    }
  
    // Picks a mode (command line or random).
  
negative.code:   void printReproductionCommand() {
      if (generate != null) {
        print([generate, '--gen-bytecode', platform, '-o', dill, fileName]
            .join(" ")
            .replaceAll('$top/', ''));
      }
      print(cmd.join(" ").replaceAll('$top/', '').replaceAll('$tmp/', ''));
    }
  
    String description;
  