Get rid of postToElement argument for accessibility notifications.

Source/modules/accessibility/AXTableRow.h

 /*
  * Copyright (C) 2008 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
@@ skipping 47 matching lines @@
     // allows the table to add other children that may not originate
     // in the row, but their col/row spans overlap into it
     void appendChild(AXObject*);
 
 protected:
     virtual AccessibilityRole determineAccessibilityRole() override final;
 
 private:
     int m_rowIndex;
 
-    virtual AXObject* observableObject() const override final;
     virtual bool computeAccessibilityIsIgnored() const override final;
 };
 
 DEFINE_AX_OBJECT_TYPE_CASTS(AXTableRow, isTableRow());
 
 } // namespace blink
 
 #endif // AXTableRow_h