Fixing up WebComponents types & tests

tests/html/element_types_test.dart

Index: tests/html/element_types_test.dart
diff --git a/tests/html/element_types_test.dart b/tests/html/element_types_test.dart
index c9ad262796c4e2e8bf58d1a99e547a3d5f26ccaa..acc20b109a009f61577c6bd63ed0cd6eb2b01a90 100644
--- a/tests/html/element_types_test.dart
+++ b/tests/html/element_types_test.dart
@@ -64,6 +64,12 @@ main() {
     });
   });
 
+  group('supported_shadow', () {
+    test('supported', () {
+      expect(ShadowElement.supported, true);
+    });
+  });
+
   group('supported_track', () {
     test('supported', () {
       expect(TrackElement.supported, true);
@@ -250,6 +256,10 @@ main() {
     test('select', () {
       expect((new SelectElement()) is SelectElement, true);
     });
+    test('shadow', () {
+      expect((new Element.tag('shadow')) is ShadowElement,
+          ShadowElement.supported);
+    });
     test('source', () {
       expect((new SourceElement()) is SourceElement, true);
     });