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

test/codegen/lib/html/range_test.dart

+library range_test;
+
+import 'dart:html';
+import 'package:unittest/unittest.dart';
+import 'package:unittest/html_individual_config.dart';
+
+main() {
+  useHtmlIndividualConfiguration();
+
+  group('supported', () {
+    test('supports_createContextualFragment', () {
+      expect(Range.supportsCreateContextualFragment, isTrue);
+    });
+  });
+
+  group('functional', () {
+    test('supported works', () {
+      var range = new Range();
+      range.selectNode(document.body);
+
+      var expectation = Range.supportsCreateContextualFragment ?
+          returnsNormally : throws;
+
+      expect(() {
+        range.createContextualFragment('<div></div>');
+      }, expectation);
+    });
+  });
+}