Revert "Add Isolate.kill()."

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);
-        echoPort.send(v - 1);
-        if (v == 2) {
-          isolate.kill(Isolate.BEFORE_NEXT_EVENT);
-        }
-      };
-      RawReceivePort exitSignal;
-      exitSignal = new RawReceivePort((_) {
-        Expect.listEquals([4, 3, 2], result);
-        exitSignal.close();
-        reply.close();
-        asyncEnd();
-      });
-      isolate.addOnExitListener(exitSignal.sendPort);
-      echoPort.send(4);
-    });
-  });
-}