Remove unused includes from various .cpp files in core/

Source/core/history/HistoryItem.cpp

 /*
  * Copyright (C) 2005, 2006, 2008, 2011 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 11 matching lines @@
  * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
  * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. 
  */
 
 #include "config.h"
 #include "core/history/HistoryItem.h"
 
 #include <stdio.h>
 #include "bindings/v8/SerializedScriptValue.h"
 #include "core/dom/Document.h"
-#include "core/platform/SharedBuffer.h"
 #include "core/platform/network/ResourceRequest.h"
 #include <wtf/CurrentTime.h>
 #include <wtf/MathExtras.h>
 #include <wtf/text/CString.h>
 
 namespace WebCore {
 
 static long long generateSequenceNumber()
 {
     // Initialize to the current time to reduce the likelihood of generating
@@ skipping 443 matching lines @@
 } // namespace WebCore
 
 #ifndef NDEBUG
 
 int showTree(const WebCore::HistoryItem* item)
 {
     return item->showTree();
 }
 
 #endif