Adding supported checks for Element.matches.

sdk/lib/html/dartium/html_dartium.dart

Index: sdk/lib/html/dartium/html_dartium.dart
diff --git a/sdk/lib/html/dartium/html_dartium.dart b/sdk/lib/html/dartium/html_dartium.dart
index f44afd146552ce267ea00d3b632645a75c37de58..366f99add4d8b3443ea992b156b9b7a6bf562b02 100644
--- a/sdk/lib/html/dartium/html_dartium.dart
+++ b/sdk/lib/html/dartium/html_dartium.dart
@@ -9316,6 +9316,14 @@ abstract class Element extends Node implements ElementTraversal {
    */
   var xtag;
 
+  /**
+   * Checks if the matches function is supported on the current platform.
+   *
+   * See also:
+   *
+   * * [matches]
+   */
+  static bool get supportsMatches => true;
 
   Element.internal() : super.internal();
 
@@ -9770,6 +9778,10 @@ abstract class Element extends Node implements ElementTraversal {
 
   @DomName('Element.webkitMatchesSelector')
   @DocsEditable
+  @SupportedBrowser(SupportedBrowser.CHROME)
+  @SupportedBrowser(SupportedBrowser.FIREFOX)
+  @SupportedBrowser(SupportedBrowser.IE, '10')
+  @SupportedBrowser(SupportedBrowser.SAFARI)
   bool matches(String selectors) native "Element_webkitMatchesSelector_Callback";
 
   @DomName('Element.webkitRequestFullScreen')