anchor.diff:    void showReproduce() {
       print("\n-- BEGIN REPRODUCE  --\n");
       print("DART SDK REVISION: $dartSdkRevision\n");
  -    print("dartfuzz.dart --${fp ? "" : "no-"}fp --${ffi ? "" : "no-"}ffi "
  +    print(
  +        "dart runtime/tools/dartfuzz/dartfuzz.dart --${fp ? "" : "no-"}fp --${ffi ? "" : "no-"}ffi "
           "--${flatTp ? "" : "no-"}flat "
           "--seed ${seed} $fileName");
       print("\n-- RUN 1 --\n");
  
positive.code:     return runCommand(cmd, env);
    }
  
    void printReproductionCommand() => print(cmd.join(" "));
  
    String description;
    String dart;
    String fileName;
    Map<String, String> env;
    List<String> cmd;
  }
  
  /// Concrete test runner of Dart AOT.
  class TestRunnerAOT implements TestRunner {
    TestRunnerAOT(String prefix, String tag, String top, String tmp,
        Map<String, String> e, this.fileName, List<String> extraFlags) {
      description = '$prefix-$tag';
      precompiler = '$top/pkg/vm/tool/precompiler2';
  
negative.code:   String dill;
    String dart;
    String fileName;
    final String top;
    final String tmp;
    Map<String, String> env;
    List<String> cmd;
  }
  
  /// Concrete test runner of Dart2JS.
  class TestRunnerDJS implements TestRunner {
    TestRunnerDJS(
        String prefix, String tag, this.top, this.tmp, this.env, this.fileName) {
      description = '$prefix-$tag';
      dart2js = '$top/sdk/bin/dart2js';
      js = '$tmp/out.js';
  