Adding supported checks for Element.matches.

tests/html/element_test.dart

 // 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
 // BSD-style license that can be found in the LICENSE file.
 
 library ElementTest;
 import '../../pkg/unittest/lib/unittest.dart';
 import '../../pkg/unittest/lib/html_individual_config.dart';
 import 'dart:html';
 import 'dart:svg' as svg;
 
@@ skipping 578 matching lines @@
       expect(el.children.removeLast(), isImageElement);
       expect(el.children.length, 1);
     });
 
     test('getRange', () {
       var el = makeElementWithChildren();
       expect(el.children.getRange(1, 1), isElementList);
     });
   });
 
+  group('supported_matches', () {
+    test('supported', () {
+      expect(Element.supportsMatches, true);
+    });
+  });
+
   group('matches', () {
     test('matches', () {
-      var element = new DivElement();
-      element.classes.add('test');
+      var expectation = Element.supportsMatches ? returnsNormally : throws;
+      expect(() {
+        var element = new DivElement();
+        element.classes.add('test');
 
-      expect(element.matches('div'), true);
-      expect(element.matches('span'), false);
-      expect(element.matches('.test'), true);
+        expect(element.matches('div'), true);
+        expect(element.matches('span'), false);
+        expect(element.matches('.test'), true);
+      }, expectation);
     });
   });
 
   group('queryAll', () {
     List<Element> getQueryAll() {
       return new Element.html("""
 <div>
   <hr/>
   <a class='q' href='http://dartlang.org'>Dart!</a>
   <p>
@@ skipping 117 matching lines @@
     });
 
     test('getRange', () {
       var range = makeElList().getRange(1, 2);
       expect(range, isElementList);
       expect(range[0], isImageElement);
       expect(range[1], isInputElement);
     });
   });
 }