Update Isolate API.

tests/isolate/kill2_test.dart

 // Copyright (c) 2014, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
 import "dart:isolate";
 import "dart:async";
 import "package:expect/expect.dart";
 import "package:async_helper/async_helper.dart";
 
 isomain1(replyPort) {
   RawReceivePort port = new RawReceivePort();
   port.handler = (v) {
     replyPort.send(v);
     if (v == 0) port.close();
   };
   replyPort.send(port.sendPort);
 }
 
 void main() {
   asyncStart();
   var completer = new Completer();  // Completed by first reply from isolate.
   RawReceivePort reply = new RawReceivePort(completer.complete);
   Isolate.spawn(isomain1, reply.sendPort).then((Isolate isolate) {
     List result = [];
     completer.future.then((echoPort) {
       reply.handler = (v) {
         result.add(v);
         if (v == 2) {
-          isolate.kill(Isolate.BEFORE_NEXT_EVENT);
+          isolate.kill(priority: Isolate.BEFORE_NEXT_EVENT);
         }
         echoPort.send(v - 1);
       };
       RawReceivePort exitSignal;
       exitSignal = new RawReceivePort((_) {
         Expect.listEquals([4, 3, 2], result);
         exitSignal.close();
         reply.close();
         asyncEnd();
       });
       isolate.addOnExitListener(exitSignal.sendPort);
       echoPort.send(4);
     });
   });
 }