Add all dart:html tests from the sdk to test/codegen.

test/codegen/lib/html/navigator_test.dart

Index: test/codegen/lib/html/navigator_test.dart
diff --git a/test/codegen/lib/html/navigator_test.dart b/test/codegen/lib/html/navigator_test.dart
new file mode 100644
index 0000000000000000000000000000000000000000..2bc5cc8912749db3e0f117b72924d5d75c71ad43
--- /dev/null
+++ b/test/codegen/lib/html/navigator_test.dart
@@ -0,0 +1,12 @@
+library NavigatorTest;
+import 'package:unittest/unittest.dart';
+import 'package:unittest/html_config.dart';
+import 'dart:html';
+
+main() {
+  useHtmlConfiguration();
+
+  test('language never returns null', () {
+      expect(window.navigator.language, isNotNull);
+    });
+}