anchor.diff:  void _call(initPort) {
     initPort.send(singleMessagePort(callFunc));
   }
  -  // Expect.throws(() {
  -  //   noReply.sendPort.send([func]);
  -  // }, null, "send wrapped");
  -
   
   void testUnsendable(name, func) {
     asyncStart();
  
positive.code: 
    // Try sending through other isolate.
    asyncStart();
    echoPort((_) => throw "unreachable")
      .then((p) => p.send(func))
      .then((p) => throw "unreachable 2",
            onError: (e, s) {asyncEnd();});
  }
  
negative.code:   // not a top-level or static function, so it should be blocked, just as
    // a normal method.
    testUnsendable("callable object", new Callable().call);
  
    asyncEnd();
    return;
  }
  