Allocate stack item for fragment context elements once

Source/core/html/parser/HTMLTreeBuilder.h

 /*
  * Copyright (C) 2010 Google, Inc. All Rights Reserved.
  * Copyright (C) 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
@@ skipping 151 matching lines @@
 
     // Default processing for the different insertion modes.
     void defaultForInitial();
     void defaultForBeforeHTML();
     void defaultForBeforeHead();
     void defaultForInHead();
     void defaultForInHeadNoscript();
     void defaultForAfterHead();
     void defaultForInTableText();
 
-    inline PassRefPtr<HTMLStackItem> adjustedCurrentStackItem() const;
+    inline HTMLStackItem* adjustedCurrentStackItem() const;
     inline bool shouldProcessTokenInForeignContent(AtomicHTMLToken*);
     void processTokenInForeignContent(AtomicHTMLToken*);
 
     Vector<Attribute> attributesForIsindexInput(AtomicHTMLToken*);
 
     void callTheAdoptionAgency(AtomicHTMLToken*);
 
     void closeTheCell();
 
     template <bool shouldClose(const HTMLStackItem*)>
@@ skipping 11 matching lines @@
     bool processEndOfFileForInTemplateContents(AtomicHTMLToken*);
 
     class FragmentParsingContext {
         WTF_MAKE_NONCOPYABLE(FragmentParsingContext);
     public:
         FragmentParsingContext();
         FragmentParsingContext(DocumentFragment*, Element* contextElement);
         ~FragmentParsingContext();
 
         DocumentFragment* fragment() const { return m_fragment; }
-        Element* contextElement() const { ASSERT(m_fragment); return m_contextElement; }
+        Element* contextElement() const { ASSERT(m_fragment); return m_contextElementStackItem->element(); }
+        HTMLStackItem* contextElementStackItem() const { ASSERT(m_fragment); return m_contextElementStackItem.get(); }
 
     private:
         DocumentFragment* m_fragment;
-        Element* m_contextElement;
+        RefPtr<HTMLStackItem> m_contextElementStackItem;
     };
 
     bool m_framesetOk;
 #ifndef NDEBUG
     bool m_isAttached;
 #endif
     FragmentParsingContext m_fragmentContext;
     HTMLConstructionSite m_tree;
 
     // http://www.whatwg.org/specs/web-apps/current-work/multipage/parsing.html#insertion-mode
@@ skipping 15 matching lines @@
 
     RefPtr<Element> m_scriptToProcess; // <script> tag which needs processing before resuming the parser.
     TextPosition m_scriptToProcessStartPosition; // Starting line number of the script tag needing processing.
 
     HTMLParserOptions m_options;
 };
 
 }
 
 #endif