anchor.diff:        this.fileName, List<String> extraFlags) {
       description = '$prefix-$tag';
       dart = '$top/out/$tag/dart';
  -    cmd = [dart] + extraFlags + [fileName];
  +    cmd = [dart, ...extraFlags, fileName];
     }
   
     TestResult run() {
  
positive.code:     description = '$prefix-$tag';
      dart = '$top/out/$tag/dart';
      if (kbcSrc) {
        cmd = [dart] + extraFlags + [fileName];
      } else {
        generate = '$top/pkg/vm/tool/gen_kernel';
        platform = '--platform=$top/out/$tag/vm_platform_strong.dill';
        dill = '$tmp/out.dill';
        cmd = [dart] + extraFlags + [dill];
      }
    }
  
  
negative.code:     snapshot = '$tmp/snapshot';
      env = Map<String, String>.from(e);
      env['DART_CONFIGURATION'] = tag;
      cmd = [precompiler, ...extraFlags, fileName, snapshot];
    }
  
    TestResult run() {
  