Added SIMD stubs for dart2js

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 92003f000e6901131275da380c361aa7ea0eb7c2..2a206c9853b65bc26b29997f567d1398395df578 100644
--- a/sdk/lib/html/dart2js/html_dart2js.dart
+++ b/sdk/lib/html/dart2js/html_dart2js.dart
@@ -29541,7 +29541,19 @@ class _LocationWrapper implements Location {
 
 
 class Platform {
+  /**
+   * Returns true if dart:typed_data types are supported on this
+   * browser.  If false, using these types will generate a runtime
+   * error.
+   */
   static final supportsTypedData = JS('bool', '!!(window.ArrayBuffer)');
+
+  /**
+   * Returns true if SIMD types in dart:typed_data types are supported
+   * on this browser.  If false, using these types will generate a runtime
+   * error.
+   */
+  static final supportsSimd = false;
 }
 // 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