Call CXFA_Object::ToNode() rather than C-style casting.

xfa/src/fxfa/src/parser/xfa_document_layout_imp.cpp

 // Copyright 2014 PDFium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 // Original code copyright 2014 Foxit Software Inc. http://www.foxitsoftware.com
 
 #include "xfa/src/foxitlib.h"
 #include "xfa/src/fxfa/src/common/xfa_utils.h"
 #include "xfa/src/fxfa/src/common/xfa_object.h"
 #include "xfa/src/fxfa/src/common/xfa_document.h"
@@ skipping 34 matching lines @@
 int32_t CXFA_LayoutProcessor::StartLayout(FX_BOOL bForceRestart) {
   if (!bForceRestart && !IsNeedLayout()) {
     return 100;
   }
   if (m_pRootItemLayoutProcessor) {
     delete m_pRootItemLayoutProcessor;
     m_pRootItemLayoutProcessor = NULL;
   }
   m_nProgressCounter = 0;
   CXFA_Node* pFormPacketNode =
-      (CXFA_Node*)m_pDocument->GetXFAObject(XFA_HASHCODE_Form);
+      ToNode(m_pDocument->GetXFAObject(XFA_HASHCODE_Form));
   if (!pFormPacketNode) {
     return -1;
   }
   CXFA_Node* pFormRoot =
       pFormPacketNode->GetFirstChildByClass(XFA_ELEMENT_Subform);
   if (!pFormRoot) {
     return -1;
   }
   if (!m_pLayoutPageMgr) {
     m_pLayoutPageMgr = new CXFA_LayoutPageMgr(this);
@@ skipping 138 matching lines @@
     : CXFA_LayoutItem(pNode, TRUE),
       m_pPrev(NULL),
       m_pNext(NULL),
       m_dwStatus(0) {
 }
 CXFA_ContentLayoutItem::~CXFA_ContentLayoutItem() {
   if (m_pFormNode->GetUserData(XFA_LAYOUTITEMKEY) == this) {
     m_pFormNode->SetUserData(XFA_LAYOUTITEMKEY, NULL);
   }
 }