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

test/codegen/lib/html/isolates_test.dart

+library IsolatesTest;
+import 'package:unittest/unittest.dart';
+import 'package:unittest/html_config.dart';
+import 'dart:async';
+import 'dart:html';
+import 'dart:convert';
+import 'dart:isolate' as isolate;
+
+String responseFor(message) => 'response for $message';
+
+void isolateEntry(isolate.SendPort initialReplyTo) {
+  var port = new isolate.ReceivePort();
+  initialReplyTo.send(port.sendPort);
+
+  bool wasThrown = false;
+  try {
+    window.alert('Test');
+  } catch (e) {
+    wasThrown = true;
+  }
+  // If wasn't thrown, do not listen to messages to make test fail.
+  if (!wasThrown) {
+    return;
+  }
+
+  // Check that convert library was loaded to isolate.
+  JSON.encode([1, 2, 3]);
+
+  port.listen((message) {
+    var data = message[0];
+    var replyTo = message[1];
+    replyTo.send(responseFor(data));
+  });
+}
+
+Future sendReceive(isolate.SendPort port, msg) {
+  var response = new isolate.ReceivePort();
+  port.send([msg, response.sendPort]);
+  return response.first;
+}
+
+main() {
+  useHtmlConfiguration();
+  test('IsolateSpawn', () {
+    var port = new isolate.ReceivePort();
+    isolate.Isolate.spawn(isolateEntry, port.sendPort);
+    port.close();
+  });
+  test('NonDOMIsolates', () {
+    var callback = expectAsync((){});
+    var response = new isolate.ReceivePort();
+    var remote = isolate.Isolate.spawn(isolateEntry, response.sendPort);
+    response.first.then((port) {
+      final msg1 = 'foo';
+      final msg2 = 'bar';
+      sendReceive(port, msg1).then((response) {
+        expect(response, equals(responseFor(msg1)));
+        sendReceive(port, msg2).then((response) {
+          expect(response, equals(responseFor(msg2)));
+          callback();
+        });
+      });
+    });
+  });
+}