Added Dartium changes onto 45.0.2454.104

LayoutTests/dart/dom/Workers.dart

+import 'package:expect/expect.dart';
+import 'package:unittest/html_config.dart';
+import 'package:unittest/unittest.dart';
+import 'dart:html';
+
+main() {
+  useHtmlConfiguration(true);
+
+  test('Workers minimal', () {
+    // FIXME: once we decide how Workers and Dart go together, this may become pure
+    // Dart test.
+    final worker = new Worker('resources/pong.js');
+    worker.onError.listen((error) => Expect.fail('error: $error'));
+    worker.onMessage.listen(expectAsync((event) {
+        Expect.equals('I am fine, thank you.', event.data);
+    }));
+    worker.postMessage('How do you do?');
+  });
+}