Fix the compile when building with STRING_STATS defined

Source/wtf/text/StringImpl.cpp

 /*
  * Copyright (C) 1999 Lars Knoll (knoll@kde.org)
  *           (C) 1999 Antti Koivisto (koivisto@kde.org)
  *           (C) 2001 Dirk Mueller ( mueller@kde.org )
  * Copyright (C) 2003, 2004, 2005, 2006, 2007, 2008, 2009, 2013 Apple Inc. All rights reserved.
  * Copyright (C) 2006 Andrew Wellington (proton@wiretapped.net)
  *
  * This library is free software; you can redistribute it and/or
  * modify it under the terms of the GNU Library General Public
  * License as published by the Free Software Foundation; either
@@ skipping 20 matching lines @@
 #include "wtf/PartitionAlloc.h"
 #include "wtf/StdLibExtras.h"
 #include "wtf/WTF.h"
 #include "wtf/text/AtomicString.h"
 #include "wtf/text/StringBuffer.h"
 #include "wtf/text/StringHash.h"
 #include "wtf/unicode/CharacterNames.h"
 
 #ifdef STRING_STATS
 #include "wtf/DataLog.h"
+#include "wtf/HashMap.h"
+#include "wtf/HashSet.h"
 #include "wtf/ProcessID.h"
 #include "wtf/RefCounted.h"
+#include "wtf/ThreadingPrimitives.h"
 #include <unistd.h>
 #endif
 
 using namespace std;
 
 namespace WTF {
 
 using namespace Unicode;
 
 COMPILE_ASSERT(sizeof(StringImpl) == 3 * sizeof(int), StringImpl_should_stay_small);
@@ skipping 2027 matching lines @@
 
 size_t StringImpl::sizeInBytes() const
 {
     size_t size = length();
     if (!is8Bit())
         size *= 2;
     return size + sizeof(*this);
 }
 
 } // namespace WTF