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

Source/WebCore/html/HTMLInputElement.cpp

Index: Source/WebCore/html/HTMLInputElement.cpp
===================================================================
--- Source/WebCore/html/HTMLInputElement.cpp	(revision 146890)
+++ Source/WebCore/html/HTMLInputElement.cpp	(working copy)
@@ -897,10 +897,8 @@
     // Ideally we'd do this from the render tree (matching
     // RenderTextView), but it's not possible to do it at the moment
     // because of the way the code is structured.
-    if (renderer()) {
-        if (AXObjectCache* cache = renderer()->document()->existingAXObjectCache())
-            cache->checkedStateChanged(this);
-    }
+    if (renderer() && AXObjectCache::accessibilityEnabled())
+        renderer()->document()->axObjectCache()->checkedStateChanged(this);
 
     // Only send a change event for items in the document (avoid firing during
     // parsing) and don't send a change event for a radio button that's getting