Revert 146726 "AXObjectCache gets recreated during document tear..."

Source/WebCore/platform/Scrollbar.cpp

 /*
  * Copyright (C) 2004, 2006, 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
  *    notice, this list of conditions and the following disclaimer in the
@@ skipping 92 matching lines @@
     // alone when sizing).
     int thickness = m_theme->scrollbarThickness(controlSize);
     Widget::setFrameRect(IntRect(0, 0, thickness, thickness));
 
     if (m_scrollableArea)
         m_currentPos = static_cast<float>(m_scrollableArea->scrollPosition(this));
 }
 
 Scrollbar::~Scrollbar()
 {
-    if (AXObjectCache* cache = existingAXObjectCache())
-        cache->remove(this);
+    if (AXObjectCache::accessibilityEnabled() && axObjectCache())
+        axObjectCache()->remove(this);
     
     stopTimerIfNeeded();
     
     m_theme->unregisterScrollbar(this);
 }
 
 ScrollbarOverlayStyle Scrollbar::scrollbarOverlayStyle() const
 {
     return m_scrollableArea ? m_scrollableArea->scrollbarOverlayStyle() : ScrollbarOverlayStyleDefault;
 }
@@ skipping 434 matching lines @@
     // Non-overlay scrollbars should always participate in hit testing.
     if (!isOverlayScrollbar())
         return true;
     return m_scrollableArea->scrollAnimator()->shouldScrollbarParticipateInHitTesting(this);
 }
 
 bool Scrollbar::isWindowActive() const
 {
     return m_scrollableArea && m_scrollableArea->isActive();
 }
-
-AXObjectCache* Scrollbar::existingAXObjectCache() const
+    
+AXObjectCache* Scrollbar::axObjectCache() const
 {
-    if (!parent())
+    if (!parent() || !parent()->isFrameView())
         return 0;
     
-    return parent()->axObjectCache();
+    // FIXME: Accessing the FrameView and Document here is a layering violation
+    // and should be removed.
+    Document* document = toFrameView(parent())->frame()->document();
+    return document->axObjectCache();
 }
 
 void Scrollbar::invalidateRect(const IntRect& rect)
 {
     if (suppressInvalidation())
         return;
 
     if (m_scrollableArea)
         m_scrollableArea->invalidateScrollbar(this, rect);
 }
@@ skipping 24 matching lines @@
 
 IntPoint Scrollbar::convertFromContainingView(const IntPoint& parentPoint) const
 {
     if (m_scrollableArea)
         return m_scrollableArea->convertFromContainingViewToScrollbar(this, parentPoint);
 
     return Widget::convertFromContainingView(parentPoint);
 }
 
 } // namespace WebCore