anchor.diff:  
   import 'dart:async';
   import 'dart:io';
  +import 'dart:isolate';
   
   import 'unittest.dart';
   import 'vm_config.dart';
  
positive.code: const int MAX_LINE = 80;
  
  class CompactVMConfiguration extends VMConfiguration {
    DateTime _start;
    int _pass = 0;
    int _fail = 0;
  
    void onInit() {
      // Override and don't call the superclass onInit() to avoid printing the
      // "unittest-suite-..." boilerplate.
    }
  
negative.code:     // Override and don't call the superclass onDone() to avoid printing the
      // "unittest-suite-..." boilerplate.
      Future.wait([stdout.close(), stderr.close()]).then((_) {
        _receivePort.close();
        exit(success ? 0 : 1);
      });
    }
  