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

test/codegen/lib/html/window_eq_test.dart

Index: test/codegen/lib/html/window_eq_test.dart
diff --git a/test/codegen/lib/html/window_eq_test.dart b/test/codegen/lib/html/window_eq_test.dart
new file mode 100644
index 0000000000000000000000000000000000000000..6995a90833f614f7ca3d47f08e1fe9e3e04c9040
--- /dev/null
+++ b/test/codegen/lib/html/window_eq_test.dart
@@ -0,0 +1,14 @@
+library WindowEqualityTest;
+import 'package:unittest/unittest.dart';
+import 'package:unittest/html_config.dart';
+import 'dart:html';
+
+main() {
+  useHtmlConfiguration();
+  var obfuscated = null;
+
+  test('notNull', () {
+      expect(window, isNotNull);
+      expect(window, isNot(equals(obfuscated)));
+    });
+}