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

test/codegen/lib/html/css_test.dart

+library CssTest;
+import 'package:unittest/unittest.dart';
+import 'package:unittest/html_individual_config.dart';
+import 'dart:html';
+
+main() {
+  useHtmlIndividualConfiguration();
+
+  group('supportsPointConversions', () {
+    test('supported', () {
+      expect(Window.supportsPointConversions, true);
+    });
+  });
+
+  group('functional', () {
+    test('DomPoint', () {
+      var expectation = Window.supportsPointConversions ?
+          returnsNormally : throws;
+      expect(() {
+        Element element = new Element.tag('div');
+        element.attributes['style'] =
+          '''
+          position: absolute;
+          width: 60px;
+          height: 100px;
+          left: 0px;
+          top: 0px;
+          background-color: red;
+          -webkit-transform: translate3d(250px, 100px, 0px);
+          -moz-transform: translate3d(250px, 100px, 0px);
+          ''';
+        document.body.append(element);
+
+        var elemRect = element.getBoundingClientRect();
+
+        checkPoint(250, 100, new Point(elemRect.left, elemRect.top));
+        checkPoint(310, 200, new Point(elemRect.right, elemRect.bottom));
+      }, expectation);
+    });
+  });
+}
+
+void checkPoint(expectedX, expectedY, Point point) {
+  expect(point.x.round(), equals(expectedX), reason: 'Wrong point.x');
+  expect(point.y.round(), equals(expectedY), reason: 'Wrong point.y');
+}