Use std::unordered_map for CFDE_CSSStyleSheet::m_StringCache

xfa/fde/css/fde_cssdeclaration.h

 // 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
 
 #ifndef XFA_FDE_CSS_FDE_CSSDECLARATION_H_
 #define XFA_FDE_CSS_FDE_CSSDECLARATION_H_
 
+#include <unordered_map>
+
 #include "xfa/fde/css/fde_cssdatatable.h"
 
 class FDE_CSSPropertyHolder : public CFX_Target {
  public:
   int16_t eProperty;
   int16_t bImportant;
   IFDE_CSSValue* pValue;
   FDE_CSSPropertyHolder* pNext;
 };
 
 class FDE_CSSCustomProperty : public CFX_Target {
  public:
   const FX_WCHAR* pwsName;
   const FX_WCHAR* pwsValue;
   FDE_CSSCustomProperty* pNext;
 };
 
 struct FDE_CSSPROPERTYARGS {
   IFX_MemoryAllocator* pStaticStore;
-  CFX_MapPtrToPtr* pStringCache;
-  FDE_LPCCSSPROPERTYTABLE pProperty;
+  std::unordered_map<uint32_t, FX_WCHAR*>* pStringCache;
+  const FDE_CSSPROPERTYTABLE* pProperty;
 };
 
 class CFDE_CSSDeclaration : public CFX_Target {
  public:
   CFDE_CSSDeclaration()
       : m_pFirstProperty(nullptr),
         m_pLastProperty(nullptr),
         m_pFirstCustom(nullptr),
         m_pLastCustom(nullptr) {}
 
@@ skipping 111 matching lines @@
                                        FDE_CSSPROPERTYVALUE eValue) const;
 
   FDE_CSSPropertyHolder* m_pFirstProperty;
   FDE_CSSPropertyHolder* m_pLastProperty;
   FDE_CSSCustomProperty* m_pFirstCustom;
   FDE_CSSCustomProperty* m_pLastCustom;
 };
 using CFDE_CSSDeclarationArray = CFX_ArrayTemplate<CFDE_CSSDeclaration*>;
 
 #endif  // XFA_FDE_CSS_FDE_CSSDECLARATION_H_