anchor.diff:    String description;
   
     // Factory.
  -  static TestRunner getTestRunner(String mode, String top, String tmp,
  +  static TestRunner getTestRunner(String mode, bool ffi, String top, String tmp,
         Map<String, String> env, String fileName, Random rand) {
       String prefix = mode.substring(0, 3).toUpperCase();
       String tag = getTag(mode);
  
positive.code:       } else if (r == 4) {
          prefix += '-DEPOPTEVERY';
          extraFlags += ['--deoptimize_every=100'];
        } else if (r == 5) {
          prefix += '-STACKTRACEEVERY';
          extraFlags += ['--stacktrace_every=100'];
        } else if (r == 6) {
  
negative.code:     rand = new Random();
      tmpDir = Directory.systemTemp.createTempSync('dart_fuzz');
      fileName = '${tmpDir.path}/fuzz.dart';
      fp = samePrecision(mode1, mode2);
      ffi = ffiCapable(mode1, mode2);
      runner1 = TestRunner.getTestRunner(
          mode1, ffi, top, tmpDir.path, env, fileName, rand);
      runner2 = TestRunner.getTestRunner(
          mode2, ffi, top, tmpDir.path, env, fileName, rand);
      isolate =
          'Isolate (${tmpDir.path}) ${ffi ? "" : "NO-"}FFI ${fp ? "" : "NO-"}FP : '
          '${runner1.description} - ${runner2.description}';
  