Add Supported class to dart:html

tools/dom/src/dart2js_Supported.dart

Index: tools/dom/src/dart2js_Supported.dart
diff --git a/tests/language/issue9664_test.dart b/tools/dom/src/dart2js_Supported.dart
similarity index 69%
copy from tests/language/issue9664_test.dart
copy to tools/dom/src/dart2js_Supported.dart
index b8b3c2db6b6277c62393bd7e44f03b26292eaf37..956f123a243c52a0784c2ab1d38da1e6b8e64bce 100644
--- a/tests/language/issue9664_test.dart
+++ b/tools/dom/src/dart2js_Supported.dart
@@ -2,8 +2,8 @@
 // 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.
 
-// Regression test for http://dartbug.com/9664
+part of html;
 
-main() {
-  while (true ? true : true) break;
+class Supported {
+  static final typeddata = JS('bool', '!!(window.ArrayBuffer)');
 }