Cleaning up event constructors

tools/dom/templates/html/impl/impl_TouchEvent.darttemplate

+// Copyright (c) 2013, 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.
+
+// WARNING: Do not edit - generated code.
+
+part of html;
+
+$(ANNOTATIONS)class $CLASSNAME$EXTENDS$IMPLEMENTS$NATIVESPEC {
+  factory $CLASSNAME(TouchList touches, TouchList targetTouches,
+      TouchList changedTouches, String type,
+      {Window view, int screenX: 0, int screenY: 0, int clientX: 0,

[Emily Fortuna, 2013/01/23 19:33:44]

tests of at least constructors for these new classes you added? Also, have we
crossed the threshold on which more classes use this format and it could benefit
from being auto-generated instead of having templates for each event class? :-)

+      int clientY: 0, bool ctrlKey: false, bool altKey: false,
+      bool shiftKey: false, bool metaKey: false}) {
+    if (view == null) {
+      view = window;
+    }
+    var e = document.$dom_createEvent("TouchEvent");
+    e.$dom_initTouchEvent(touches, targetTouches, changedTouches, type, view,
+        screenX, screenY, clientX, clientY, ctrlKey, altKey, shiftKey, metaKey);
+    return e;
+  }
+$!MEMBERS
+}