anchor.diff:      expect(isolate.extensionRPCs, contains('ext..delay'));
       expect(isolate.extensionRPCs, isNot(contains('ext..error')));
       expect(isolate.extensionRPCs, isNot(contains('ext..exception')));
  -    expect(isolate.extensionRPCs, isNot(contains('ext..null')));
  -    expect(isolate.extensionRPCs, isNot(contains('ext..nullFuture')));
       expect(isolate.extensionRPCs, isNot(contains('ext..success')));
     },
     resumeIsolateAndAwaitEvent(Isolate.kExtensionStream, (ServiceEvent event) {
  
positive.code:         'method': method,
          'parameters': paremeters,
        })));
      case 'ext..null':
        return null;
      case 'ext..nullFuture':
        return new Future<ServiceExtensionResponse>.value(null);
    }
  }
  
  
negative.code:       expect(e.message.startsWith('I always throw!\n'), isTrue);
      }
  
      result =
          await isolate.invokeRpcNoUpgrade('ext..success', {'apple': 'banana'});
      expect(result['type'], equals('_extensionType'));
  