Remove old isolate API and update all code in the repository to use

tests/isolate/constructor_test.dart

-// Copyright (c) 2011, 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.
-
-#library("ConstructorTest");
-#import("dart:isolate");
-#import('../../lib/unittest/unittest.dart');
-
-class ConstructorTest extends Isolate {
-  final int field;
-  ConstructorTest() : super(), field = 499;
-
-  void main() {
-    this.port.receive((ignoredMessage, reply) {
-      reply.send(field, null);
-      this.port.close();
-    });
-  }
-}
-
-main() {
-  test("constructor correctly initialized child isolate", () {
-    ConstructorTest test = new ConstructorTest();
-    test.spawn().then(expectAsync1((SendPort port) {
-      port.call("ignored").then(expectAsync1((message) {
-        Expect.equals(499, message);
-      }));
-    }));
-  });
-}