Oilpan: Make ActiveParserSession::m_document traceable.

Source/core/html/parser/NestingLevelIncrementer.h

 /*
  * Copyright (C) 2010 Google, 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
  *    documentation and/or other materials provided with the distribution.
  *
  * THIS SOFTWARE IS PROVIDED BY APPLE INC. ``AS IS'' AND ANY
  * EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
  * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL APPLE INC. OR
  * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
  * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
  * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
  * PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY
  * OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
  * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
  * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  */
 
 #ifndef NestingLevelIncrementer_h
 #define NestingLevelIncrementer_h
 
+#include "platform/heap/Handle.h"
 #include "wtf/Noncopyable.h"
 
 namespace WebCore {
 
 class NestingLevelIncrementer {
+    STACK_ALLOCATED();
     WTF_MAKE_NONCOPYABLE(NestingLevelIncrementer);
 public:
     explicit NestingLevelIncrementer(unsigned& nestingLevel)
         : m_nestingLevel(&nestingLevel)
     {
         ++(*m_nestingLevel);
     }
 
     ~NestingLevelIncrementer()
     {
         --(*m_nestingLevel);
     }
 
 private:
     unsigned* m_nestingLevel;
 };
 
 }
 
 #endif