Forward BrowserAccessibilityWin::get_accKeyboardShortcut to the platform node

ui/accessibility/ax_enums.idl

 // Copyright 2014 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 // TODO(nektar): Migrate entire file to Mojoq.
 // These should be kept in sync with third_party/WebKit/public/web/WebAXEnums.h
 // until the Chromium and Blink trees are merged.
 [camel_case_enum_to_string=true] namespace ui {
 
   // For new entries to the following four enums, also add to
@@ skipping 329 matching lines @@
     inner_html,
     key_shortcuts,
     // Only present when different from parent.
     language,
     name,
     live_relevant,
     live_status,
     placeholder,
     role,
     role_description,
-    shortcut,
     url,
     value
   };
 
   [cpp_enum_prefix_override="ax_attr"] enum AXIntAttribute {
     default_action_verb,
     // Scrollable container attributes.
     scroll_x,
     scroll_x_min,
     scroll_x_max,
@@ skipping 312 matching lines @@
     // First node is before the second one.
     before,
 
     // Nodes are the same.
     equal,
 
     // First node is after the second one.
     after
   };
 };