Fix Timers in isolates in dart2js.

tests/isolate/timer_isolate_test.dart

+// Copyright (c) 2012, 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('multiple_timer_test');
+
+#import("dart:isolate");
+#import('../../pkg/unittest/unittest.dart');
+
+const int TIMEOUT = 100;
+
+createTimer() {
+  port.receive((msg, replyTo) {
+    new Timer(TIMEOUT, (_) {
+      replyTo.send("timer_fired");
+    });
+  });
+}
+
+main() {
+  test("timer in isolate", () {
+    int startTime;
+    int endTime;
+    
+    port.receive(expectAsync2((msg, _) {
+      expect("timer_fired", msg);
+      int endTime = (new Date.now()).millisecondsSinceEpoch;
+      expect((endTime - startTime) >= TIMEOUT);
+    }));
+    
+    startTime = (new Date.now()).millisecondsSinceEpoch;
+    var sendPort = spawnFunction(createTimer);
+    sendPort.send("sendPort", port.toSendPort());
+  });
+}