Have Frame::tree() return a reference

Source/core/xml/parser/XMLDocumentParser.cpp

 /*
  * Copyright (C) 2000 Peter Kelly (pmk@post.com)
  * Copyright (C) 2005, 2006, 2008 Apple Inc. All rights reserved.
  * Copyright (C) 2006 Alexey Proskuryakov (ap@webkit.org)
  * Copyright (C) 2007 Samuel Weinig (sam@webkit.org)
  * Copyright (C) 2008 Nokia Corporation and/or its subsidiary(-ies)
  * Copyright (C) 2008 Holger Hans Peter Freyther
  * Copyright (C) 2008 Torch Mobile Inc. All rights reserved. (http://www.torchmobile.com/)
  *
  * This library is free software; you can redistribute it and/or
@@ skipping 92 matching lines @@
 }
 
 static inline bool hasNoStyleInformation(Document* document)
 {
     if (document->sawElementsInKnownNamespaces() || document->transformSourceDocument())
         return false;
 
     if (!document->frame() || !document->frame()->page())
         return false;
 
-    if (document->frame()->tree()->parent())
+    if (document->frame()->tree().parent())
         return false; // This document is not in a top frame
 
     return true;
 }
 
 class PendingStartElementNSCallback FINAL : public XMLDocumentParser::PendingCallback {
 public:
     PendingStartElementNSCallback(const AtomicString& localName, const AtomicString& prefix, const AtomicString& uri,
         int namespaceCount, const xmlChar** namespaces, int attributeCount, int defaultedCount, const xmlChar** attributes)
         : m_localName(localName)
@@ skipping 1511 matching lines @@
     sax.initialized = XML_SAX2_MAGIC;
     RefPtr<XMLParserContext> parser = XMLParserContext::createStringParser(&sax, &state);
     String parseString = "<?xml version=\"1.0\"?><attrs " + string + " />";
     parseChunk(parser->context(), parseString);
     finishParsing(parser->context());
     attrsOK = state.gotAttributes;
     return state.attributes;
 }
 
 } // namespace WebCore