Check whether aria-expanded attribute is defined

Source/core/accessibility/AXObject.h

 /*
  * Copyright (C) 2008, 2009, 2011 Apple Inc. All rights reserved.
  * Copyright (C) 2008 Nuanti Ltd.
  *
  * 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.
@@ skipping 430 matching lines @@
     virtual bool ariaRoleHasPresentationalChildren() const { return false; }
     virtual bool isARIAGrabbed() { return false; }
     virtual bool isPresentationalChildOfAriaRole() const { return false; }
     virtual bool shouldFocusActiveDescendant() const { return false; }
     bool supportsARIAAttributes() const;
     virtual bool supportsARIADragging() const { return false; }
     virtual bool supportsARIADropping() const { return false; }
     virtual bool supportsARIAFlowTo() const { return false; }
     virtual bool supportsARIAOwns() const { return false; }
     bool supportsRangeValue() const;
+    virtual bool supportsARIAExpanded() const { return false; }
 
     // ARIA trees.
     // Used by an ARIA tree to get all its rows.
     void ariaTreeRows(AccessibilityChildrenVector&);
 
     // ARIA live-region features.
     bool supportsARIALiveRegion() const;
     virtual const AtomicString& ariaLiveRegionStatus() const { return nullAtom; }
     virtual const AtomicString& ariaLiveRegionRelevant() const { return nullAtom; }
     virtual bool ariaLiveRegionAtomic() const { return false; }
@@ skipping 119 matching lines @@
 
     bool m_detached;
 };
 
 #define DEFINE_AX_OBJECT_TYPE_CASTS(thisType, predicate) \
     DEFINE_TYPE_CASTS(thisType, AXObject, object, object->predicate, object.predicate)
 
 } // namespace blink
 
 #endif // AXObject_h