Add Supported class to dart:html

sdk/lib/html/dart2js/html_dart2js.dart

Index: sdk/lib/html/dart2js/html_dart2js.dart
diff --git a/sdk/lib/html/dart2js/html_dart2js.dart b/sdk/lib/html/dart2js/html_dart2js.dart
index b18f079a9551b67d0572c1fbb6eb32ffe25da48a..e524ba62a71550b607bb4eed2dea5f8e17de04ad 100644
--- a/sdk/lib/html/dart2js/html_dart2js.dart
+++ b/sdk/lib/html/dart2js/html_dart2js.dart
@@ -413,9 +413,6 @@ class ArrayBuffer native "*ArrayBuffer" {
   }
   static ArrayBuffer _create_1(length) => JS('ArrayBuffer', 'new ArrayBuffer(#)', length);
 
-  /// Checks if this type is supported on the current platform.
-  static bool get supported => JS('bool', 'typeof window.ArrayBuffer != "undefined"');
-
   @DomName('ArrayBuffer.byteLength')
   @DocsEditable
   final int byteLength;
@@ -32067,6 +32064,14 @@ class _LocationWrapper implements Location {
   static _get(p, m) => JS('var', '#[#]', p, m);
   static _set(p, m, v) => JS('void', '#[#] = #', p, m, v);
 }
+// Copyright (c) 2013, 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.
+
+
+class Platform {
+  static final supportsTypedData = JS('bool', '!!(window.ArrayBuffer)');
+}
 // 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.