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

Source/WebCore/rendering/RenderBlock.cpp

Index: Source/WebCore/rendering/RenderBlock.cpp
===================================================================
--- Source/WebCore/rendering/RenderBlock.cpp	(revision 146890)
+++ Source/WebCore/rendering/RenderBlock.cpp	(working copy)
@@ -1001,12 +1001,11 @@
         }
     }
     m_lineBoxes.deleteLineBoxTree(renderArena());
-
-    if (AXObjectCache* cache = document()->existingAXObjectCache())
-        cache->recomputeIsIgnored(this);
+    if (UNLIKELY(AXObjectCache::accessibilityEnabled()))
+        document()->axObjectCache()->recomputeIsIgnored(this);
 }
 
-RootInlineBox* RenderBlock::createRootInlineBox()
+RootInlineBox* RenderBlock::createRootInlineBox() 
 {
     return new (renderArena()) RootInlineBox(this);
 }
@@ -1016,10 +1015,8 @@
     RootInlineBox* rootBox = createRootInlineBox();
     m_lineBoxes.appendLineBox(rootBox);
 
-    if (UNLIKELY(AXObjectCache::accessibilityEnabled()) && m_lineBoxes.firstLineBox() == rootBox) {
-        if (AXObjectCache* cache = document()->existingAXObjectCache())
-            cache->recomputeIsIgnored(this);
-    }
+    if (UNLIKELY(AXObjectCache::accessibilityEnabled()) && m_lineBoxes.firstLineBox() == rootBox)
+        document()->axObjectCache()->recomputeIsIgnored(this);
 
     return rootBox;
 }