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

test/codegen/lib/html/unknownelement_test.dart

+// Copyright (c) 2012, 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 UnknownElementTest;
+import 'package:unittest/unittest.dart';
+import 'package:unittest/html_config.dart';
+import 'dart:html';
+
+main() {
+  useHtmlConfiguration();
+
+  var isUnknownElement =
+      predicate((x) => x is UnknownElement, 'is an UnknownELement');
+
+  var foo = new Element.tag('foo');
+  foo.id = 'foo';
+  var bar = new Element.tag('bar');
+  bar.id = 'bar';
+  document.body.nodes.addAll([foo, bar]);
+
+  test('type-check', () {
+      expect(foo, isUnknownElement);
+      expect(bar, isUnknownElement);
+      expect(query('#foo'), equals(foo));
+      expect(query('#bar'), equals(bar));
+    });
+
+  test('dispatch-fail', () {
+      expect(() => foo.method1(), throwsNoSuchMethodError);
+      expect(() => foo.field1, throwsNoSuchMethodError);
+      expect(() { foo.field1 = 42; }, throwsNoSuchMethodError);
+    });
+}