Implement aria properties setsize and posinset.

Source/modules/accessibility/AXNodeObject.h

 /*
  * Copyright (C) 2012, 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:
  *
  * 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
@@ skipping 177 matching lines @@
     virtual void setFocused(bool) override final;
     virtual void increment() override final;
     virtual void decrement() override final;
 
     // Notifications that this object may have changed.
     virtual void childrenChanged() override;
     virtual void selectionChanged() override final;
     virtual void textChanged() override;
     virtual void updateAccessibilityRole() override final;
 
+    virtual int posInSet() const override;
+    virtual int setSize() const override;
+
 private:
     Node* m_node;
 
     String alternativeTextForWebArea() const;
     void alternativeText(Vector<AccessibilityText>&) const;
     void ariaLabeledByText(Vector<AccessibilityText>&) const;
     void changeValueByPercent(float percentChange);
     float stepValueForRange() const;
     AXObject* findChildWithTagName(const HTMLQualifiedName&) const;
 };
 
 DEFINE_AX_OBJECT_TYPE_CASTS(AXNodeObject, isAXNodeObject());
 
 } // namespace blink
 
 #endif // AXNodeObject_h