Add constructors to all the event classes.

client/html/src/DeviceOrientationEventWrappingImplementation.dart

+// Copyright (c) 2011, 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.
+
+class DeviceOrientationEventWrappingImplementation extends EventWrappingImplementation implements DeviceOrientationEvent {
+  DeviceOrientationEventWrappingImplementation._wrap(ptr) : super._wrap(ptr);
+
+  factory DeviceOrientationEventWrappingImplementation(String type,
+      double alpha, double beta, double gamma, [bool canBubble = true,
+      bool cancelable = true]) {
+    final e = dom.document.createEvent("DeviceOrientationEvent");
+    e.initDeviceOrientationEvent(
+        type, canBubble, cancelable, alpha, beta, gamma);
+    return LevelDom.wrapDeviceOrientationEvent(e);
+  }
+
+  num get alpha() => _ptr.alpha;
+
+  num get beta() => _ptr.beta;
+
+  num get gamma() => _ptr.gamma;
+}