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

public/web/WebAXObject.h

 /*
  * 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 79 matching lines @@
     BLINK_EXPORT WebAXObject parentObject() const;
 
     BLINK_EXPORT bool isAnchor() const;
     BLINK_EXPORT bool isAriaReadOnly() const;
     BLINK_EXPORT bool isButtonStateMixed() const;
     BLINK_EXPORT bool isChecked() const;
     BLINK_EXPORT bool isClickable() const;
     BLINK_EXPORT bool isCollapsed() const;
     BLINK_EXPORT bool isControl() const;
     BLINK_EXPORT bool isEnabled() const;
+    BLINK_EXPORT bool isExpanded() const;
     BLINK_EXPORT bool isFocused() const;
     BLINK_EXPORT bool isHovered() const;
     BLINK_EXPORT bool isIndeterminate() const;
     BLINK_EXPORT bool isLinked() const;
     BLINK_EXPORT bool isLoaded() const;
     BLINK_EXPORT bool isMultiSelectable() const;
     BLINK_EXPORT bool isOffScreen() const;
     BLINK_EXPORT bool isPasswordField() const;
     BLINK_EXPORT bool isPressed() const;
     BLINK_EXPORT bool isReadOnly() const;
@@ skipping 105 matching lines @@
     operator WTF::PassRefPtr<AXObject>() const;
 #endif
 
 private:
     WebPrivatePtr<AXObject> m_private;
 };
 
 } // namespace blink
 
 #endif