AXScrollbar should not be recreated right after removal

Source/core/frame/FrameView.h

 /*
    Copyright (C) 1997 Martin Jones (mjones@kde.org)
              (C) 1998 Waldo Bastian (bastian@kde.org)
              (C) 1998, 1999 Torben Weis (weis@kde.org)
              (C) 1999 Lars Knoll (knoll@kde.org)
              (C) 1999 Antti Koivisto (koivisto@kde.org)
    Copyright (C) 2004, 2005, 2006, 2007, 2008, 2009 Apple Inc. All rights reserved.
 
    This library is free software; you can redistribute it and/or
    modify it under the terms of the GNU Library General Public
@@ skipping 298 matching lines @@
     // On Mac WebKit1 the underlying NSScrollView just does the scrolling, but on most other platforms
     // we need this function in order to do the scroll ourselves.
     ScrollResult wheelEvent(const PlatformWheelEvent&);
 
     virtual bool shouldUseIntegerScrollOffset() const override;
 
     virtual bool isActive() const override;
 
     // Override scrollbar notifications to update the AXObject cache.
     virtual void didAddScrollbar(Scrollbar*, ScrollbarOrientation) override;
-    virtual void willRemoveScrollbar(Scrollbar*, ScrollbarOrientation) override;
 
     // FIXME: This should probably be renamed as the 'inSubtreeLayout' parameter
     // passed around the FrameView layout methods can be true while this returns
     // false.
     bool isSubtreeLayout() const { return !m_layoutSubtreeRoots.isEmpty(); }
 
     // Sets the tickmarks for the FrameView, overriding the default behavior
     // which is to display the tickmarks corresponding to find results.
     // If |m_tickmarks| is empty, the default behavior is restored.
     void setTickmarks(const Vector<IntRect>& tickmarks)
@@ skipping 538 matching lines @@
     static const unsigned visualPixelThreshold = 32 * 32;
     if (m_visuallyNonEmptyPixelCount > visualPixelThreshold)
         setIsVisuallyNonEmpty();
 }
 
 DEFINE_TYPE_CASTS(FrameView, Widget, widget, widget->isFrameView(), widget.isFrameView());
 
 } // namespace blink
 
 #endif // FrameView_h