Add isExpanded() API to WebAXObject.h to get aria-expanded attribute.

Source/web/WebAXObject.cpp

 /*
  * Copyright (C) 2009 Google 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:
  *
  *     * Redistributions of source code must retain the above copyright
  * notice, this list of conditions and the following disclaimer.
  *     * Redistributions in binary form must reproduce the above
@@ skipping 256 matching lines @@
 }
 
 bool WebAXObject::isEnabled() const
 {
     if (isDetached())
         return 0;
 
     return m_private->isEnabled();
 }
 
+bool WebAXObject::isExpanded() const
+{
+    if (isDetached())
+        return 0;
+
+    return m_private->isExpanded();
+}
+
 bool WebAXObject::isFocused() const
 {
     if (isDetached())
         return 0;
 
     return m_private->isFocused();
 }
 
 bool WebAXObject::isHovered() const
 {
@@ skipping 876 matching lines @@
     m_private = object;
     return *this;
 }
 
 WebAXObject::operator WTF::PassRefPtr<AXObject>() const
 {
     return m_private.get();
 }
 
 } // namespace blink