Properly fix the warnings

xfa/fxfa/parser/xfa_object_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/fxfa/parser/xfa_object.h"
 
 #include "core/fxcrt/include/fx_ext.h"
 #include "xfa/fde/xml/fde_xml_imp.h"
@@ skipping 4556 matching lines @@
       if (iCount > index) {
         return pNode;
       }
     }
   }
   return NULL;
 }
 int32_t CXFA_Node::InsertChild(int32_t index, CXFA_Node* pNode) {
   ASSERT(!pNode->m_pNext);
   pNode->m_pParent = this;
-  ASSERT(m_pDocument->RemovePurgeNode(pNode));
+  FX_BOOL ret = m_pDocument->RemovePurgeNode(pNode);
+  ASSERT(ret);
 
   if (m_pChild == NULL || index == 0) {
     if (index > 0) {
       return -1;
     }
     pNode->m_pNext = m_pChild;
     m_pChild = pNode;
     index = 0;
   } else if (index < 0) {
     m_pLastChild->m_pNext = pNode;
@@ skipping 27 matching lines @@
   }
   return index;
 }
 
 FX_BOOL CXFA_Node::InsertChild(CXFA_Node* pNode, CXFA_Node* pBeforeNode) {
   if (!pNode || pNode->m_pParent ||
       (pBeforeNode && pBeforeNode->m_pParent != this)) {
     ASSERT(false);
     return FALSE;
   }
-  ASSERT(m_pDocument->RemovePurgeNode(pNode));
+  FX_BOOL ret = m_pDocument->RemovePurgeNode(pNode);
+  ASSERT(ret);
 
   int32_t nIndex = -1;
   pNode->m_pParent = this;
   if (m_pChild == NULL || pBeforeNode == m_pChild) {
     pNode->m_pNext = m_pChild;
     m_pChild = pNode;
     nIndex = 0;
   } else if (!pBeforeNode) {
     pNode->m_pNext = m_pLastChild->m_pNext;
     m_pLastChild->m_pNext = pNode;
@@ skipping 741 matching lines @@
   return m_pAttachNode->InsertChild(pNewNode, pBeforeNode);
 }
 FX_BOOL CXFA_AttachNodeList::Remove(CXFA_Node* pNode) {
   return m_pAttachNode->RemoveChild(pNode);
 }
 CXFA_Node* CXFA_AttachNodeList::Item(int32_t iIndex) {
   return m_pAttachNode->GetChild(
       iIndex, XFA_ELEMENT_UNKNOWN,
       m_pAttachNode->GetClassID() == XFA_ELEMENT_Subform);
 }