Fix crash in hidden <select>

third_party/WebKit/Source/modules/accessibility/AXMenuList.h

 /*
  * Copyright (C) 2010 Apple Inc. All Rights Reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions
  * are met:
  * 1. Redistributions of source code must retain the above copyright
  *    notice, this list of conditions and the following disclaimer.
  * 2. Redistributions in binary form must reproduce the above copyright
  *    notice, this list of conditions and the following disclaimer in the
@@ skipping 31 matching lines @@
   bool IsCollapsed() const override;
   AccessibilityExpanded IsExpanded() const final;
   bool Press() override;
   void ClearChildren() override;
 
   void DidUpdateActiveOption(int option_index);
   void DidShowPopup();
   void DidHidePopup();
 
  private:
+  friend class AXMenuListOption;
+
   AXMenuList(LayoutMenuList*, AXObjectCacheImpl&);
 
   bool IsMenuList() const override { return true; }
   AccessibilityRole DetermineAccessibilityRole() final;
   bool CanSetFocusAttribute() const override;
 
   void AddChildren() override;
 };
 
 DEFINE_AX_OBJECT_TYPE_CASTS(AXMenuList, IsMenuList());
 
 }  // namespace blink
 
 #endif  // AXMenuList_h