Add a test to check ArrayBuffer passing.

tests/html/transferables_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('TransferableTest');
+#import('../../lib/unittest/unittest.dart');
+#import('../../lib/unittest/html_config.dart');
+#import('dart:html');
+
+main() {
+  useHtmlConfiguration();
+
+  asyncTest('TransferableTest', 1, () {
+    window.on.message.add((messageEvent) {
+      expect(messageEvent.data is ArrayBuffer).isTrue();
+      callbackDone();
+    });
+    final buffer = (new Float32Array(3)).buffer;
+    window.webkitPostMessage(buffer, '*', [buffer]);
+  });
+}