Cleaning up dart:html generation after interface/implementation merge. Removing most of the interfa…

sdk/lib/html/templates/html/interface/interface_MouseEvent.darttemplate

-// Copyright (c) 2012, 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;
-
-$!COMMENT
-abstract class $ID$EXTENDS {
-
-  factory $ID(String type, Window view, int detail, int screenX, int screenY,
-      int clientX, int clientY, int button, [bool canBubble = true,
-      bool cancelable = true, bool ctrlKey = false, bool altKey = false,
-      bool shiftKey = false, bool metaKey = false,
-      EventTarget relatedTarget = null]) =>
-      _$(ID)FactoryProvider.create$ID(
-          type, view, detail, screenX, screenY,
-          clientX, clientY, button, canBubble, cancelable,
-          ctrlKey, altKey, shiftKey, metaKey,
-          relatedTarget);
-
-$!MEMBERS}