Oilpan: mark WebPageSerializerImpl as stack allocated.

Source/web/WebPageSerializerImpl.cpp

 /*
  * Copyright (C) 2009 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:
  *
  *     * Redistributions of source code must retain the above copyright
  * notice, this list of conditions and the following disclaimer.
  *     * Redistributions in binary form must reproduce the above
@@ skipping 94 matching lines @@
                                                             const WTF::TextEncoding& textEncoding,
                                                             Document* document,
                                                             const String& directoryName)
     : url(url)
     , textEncoding(textEncoding)
     , document(document)
     , directoryName(directoryName)
     , isHTMLDocument(document->isHTMLDocument())
     , haveSeenDocType(false)
     , haveAddedCharsetDeclaration(false)
-    , skipMetaElement(0)
+    , skipMetaElement(nullptr)
     , isInScriptOrStyleTag(false)
     , haveAddedXMLProcessingDirective(false)
     , haveAddedContentsBeforeEnd(false)
 {
 }
 
 String WebPageSerializerImpl::preActionBeforeSerializeOpenTag(
     const Element* element, SerializeDomParam* param, bool* needSkip)
 {
     StringBuilder result;
@@ skipping 386 matching lines @@
 
         encodeAndFlushBuffer(WebPageSerializerClient::CurrentFrameIsFinished, &param, ForceFlush);
     }
 
     ASSERT(m_dataBuffer.isEmpty());
     m_client->didSerializeDataForFrame(KURL(), WebCString("", 0), WebPageSerializerClient::AllFramesAreFinished);
     return didSerialization;
 }
 
 }  // namespace blink