Add constructors to all the event classes.

client/html/src/TouchEventWrappingImplementation.dart

Index: client/html/src/TouchEventWrappingImplementation.dart
diff --git a/client/html/src/TouchEventWrappingImplementation.dart b/client/html/src/TouchEventWrappingImplementation.dart
new file mode 100644
index 0000000000000000000000000000000000000000..5b580b6e0d34ee9826ab89cdfa81ca72e6877e39
--- /dev/null
+++ b/client/html/src/TouchEventWrappingImplementation.dart
@@ -0,0 +1,32 @@
+// 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 TouchEventWrappingImplementation extends UIEventWrappingImplementation implements TouchEvent {
+  TouchEventWrappingImplementation._wrap(ptr) : super._wrap(ptr);
+
+  TouchEvent(TouchList touches, TouchList targetTouches,
+      TouchList changedTouches, String type, Window view, int screenX,
+      int screenY, int clientX, int clientY, [bool ctrlKey = false,
+      bool altKey = false, bool shiftKey = false, bool metaKey = false]) {
+    final e = dom.document.createEvent("TouchEvent");
+    e.initTouchEvent(LevelDom.unwrap(touches), LevelDom.unwrap(targetTouches),
+        LevelDom.unwrap(changedTouches), type, LevelDom.unwrap(view), screenX,
+        screenY, clientX, clientY, ctrlKey, altKey, shiftKey, metaKey);
+    return LevelDom.wrapTouchEvent(e);
+  }
+
+  bool get altKey() => _ptr.altKey;
+
+  TouchList get changedTouches() => LevelDom.wrapTouchList(_ptr.changedTouches);
+
+  bool get ctrlKey() => _ptr.ctrlKey;
+
+  bool get metaKey() => _ptr.metaKey;
+
+  bool get shiftKey() => _ptr.shiftKey;
+
+  TouchList get targetTouches() => LevelDom.wrapTouchList(_ptr.targetTouches);
+
+  TouchList get touches() => LevelDom.wrapTouchList(_ptr.touches);
+}