Exposing ARIA state/property aria-orientation on Windows correctly.

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.
 
 // 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 three enums, also add to
   // chrome/common/extensions/api/automation.idl.
@@ skipping 183 matching lines @@
     checked,
     collapsed,
     default,
     disabled,  // ui/views only
     editable,  // ui/views only
     enabled,   // content only
     expanded,
     focusable,
     focused,
     haspopup,
+    horizontal,
     hovered,
     indeterminate,
     invisible,
     linked,
     multiselectable,
     offscreen,
     pressed,
     protected,
     read_only,
     required,
@@ skipping 165 matching lines @@
     word_ends
   };
 
   [cpp_enum_prefix_override="ax"] enum AXTextDirection {
     text_direction_lr,
     text_direction_rl,
     text_direction_tb,
     text_direction_bt
   };
 };