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

test/codegen/lib/html/exceptions_test.dart

+library ExceptionsTest;
+import 'package:unittest/unittest.dart';
+import 'package:unittest/html_config.dart';
+import 'dart:html';
+
+main() {
+  useHtmlConfiguration();
+
+  test('EventException', () {
+    final event = new Event('Event');
+    // Intentionally do not initialize it!
+    try {
+      document.dispatchEvent(event);
+    } on DomException catch (e) {
+      expect(e.name, DomException.INVALID_STATE);
+    }
+  });
+}