Adding supported checks & test for SpeechRecognition APIs.

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 6276aa70662e848dcf08f2e26ffed8a334f8b82f..a26637db2106e4d89df13a195619a785a8fbcd32 100644
--- a/sdk/lib/html/dart2js/html_dart2js.dart
+++ b/sdk/lib/html/dart2js/html_dart2js.dart
@@ -20360,7 +20360,7 @@ class SpeechInputResult native "*SpeechInputResult" {
   @DomName('SpeechInputResult.utterance')
   final String utterance;
 }
-// Copyright (c) 2012, the Dart project authors.  Please see the AUTHORS file
+// 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.
 
@@ -20368,6 +20368,8 @@ class SpeechInputResult native "*SpeechInputResult" {
 
 @DocsEditable
 @DomName('SpeechRecognition')
+@SupportedBrowser(SupportedBrowser.CHROME, '25')
+@Experimental()
 class SpeechRecognition extends EventTarget native "*SpeechRecognition" {
 
   @DocsEditable
@@ -20416,7 +20418,9 @@ class SpeechRecognition extends EventTarget native "*SpeechRecognition" {
 
   @DocsEditable
   factory SpeechRecognition() => SpeechRecognition._create();
-  static SpeechRecognition _create() => JS('SpeechRecognition', 'new SpeechRecognition()');
+
+  /// Checks if this type is supported on the current platform.
+  static bool get supported => JS('bool', '!!(window.SpeechRecognition || window.webkitSpeechRecognition)');
 
   @DocsEditable
   @DomName('EventTarget.addEventListener, EventTarget.removeEventListener, EventTarget.dispatchEvent')
@@ -20513,6 +20517,11 @@ class SpeechRecognition extends EventTarget native "*SpeechRecognition" {
   @DocsEditable
   @DomName('SpeechRecognition.start')
   Stream<Event> get onStart => startEvent.forTarget(this);
+
+  static SpeechRecognition _create() {
+    return JS('SpeechRecognition',
+        'new (window.SpeechRecognition || window.webkitSpeechRecognition)()');
+  }
 }
 
 @DocsEditable
@@ -20561,6 +20570,8 @@ class SpeechRecognitionEvents extends Events {
 
 @DocsEditable
 @DomName('SpeechRecognitionAlternative')
+@SupportedBrowser(SupportedBrowser.CHROME, '25')
+@Experimental()
 class SpeechRecognitionAlternative native "*SpeechRecognitionAlternative" {
 
   @DocsEditable
@@ -20579,6 +20590,8 @@ class SpeechRecognitionAlternative native "*SpeechRecognitionAlternative" {
 
 @DocsEditable
 @DomName('SpeechRecognitionError')
+@SupportedBrowser(SupportedBrowser.CHROME, '25')
+@Experimental()
 class SpeechRecognitionError extends Event native "*SpeechRecognitionError" {
 
   @DocsEditable
@@ -20597,6 +20610,8 @@ class SpeechRecognitionError extends Event native "*SpeechRecognitionError" {
 
 @DocsEditable
 @DomName('SpeechRecognitionEvent')
+@SupportedBrowser(SupportedBrowser.CHROME, '25')
+@Experimental()
 class SpeechRecognitionEvent extends Event native "*SpeechRecognitionEvent" {
 
   @DocsEditable
@@ -20627,6 +20642,8 @@ class SpeechRecognitionEvent extends Event native "*SpeechRecognitionEvent" {
 
 @DocsEditable
 @DomName('SpeechRecognitionResult')
+@SupportedBrowser(SupportedBrowser.CHROME, '25')
+@Experimental()
 class SpeechRecognitionResult native "*SpeechRecognitionResult" {
 
   @DocsEditable