Use std::map as CPDF_Dictionary's underlying store.

core/src/fpdfapi/fpdf_edit/fpdf_edit_create.cpp

Index: core/src/fpdfapi/fpdf_edit/fpdf_edit_create.cpp
diff --git a/core/src/fpdfapi/fpdf_edit/fpdf_edit_create.cpp b/core/src/fpdfapi/fpdf_edit/fpdf_edit_create.cpp
index 328728ef2410f01b67fbe4d1ccbbc5edb83f7c29..654d9680100c5dac49944ab8647e124505da7e7b 100644
--- a/core/src/fpdfapi/fpdf_edit/fpdf_edit_create.cpp
+++ b/core/src/fpdfapi/fpdf_edit/fpdf_edit_create.cpp
@@ -108,10 +108,9 @@ int32_t PDF_CreatorAppendObject(const CPDF_Object* pObj,
       }
       offset += 2;
       const CPDF_Dictionary* p = pObj->AsDictionary();
-      FX_POSITION pos = p->GetStartPos();
-      while (pos) {
-        CFX_ByteString key;
-        CPDF_Object* pValue = p->GetNextElement(pos, key);
+      for (const auto& it : *p) {
+        const CFX_ByteString& key = it.first;
+        CPDF_Object* pValue = it.second;
         if (pFile->AppendString("/") < 0) {
           return -1;
         }
@@ -179,10 +178,9 @@ int32_t PDF_CreatorWriteTrailer(CPDF_Document* pDocument,
   CPDF_Parser* pParser = (CPDF_Parser*)pDocument->GetParser();
   if (pParser) {
     CPDF_Dictionary* p = pParser->GetTrailer();
-    FX_POSITION pos = p->GetStartPos();
-    while (pos) {
-      CFX_ByteString key;
-      CPDF_Object* pValue = p->GetNextElement(pos, key);
+    for (const auto& it : *p) {
+      const CFX_ByteString& key = it.first;
+      CPDF_Object* pValue = it.second;
       if (key == "Encrypt" || key == "Size" || key == "Filter" ||
           key == "Index" || key == "Length" || key == "Prev" || key == "W" ||
           key == "XRefStm" || key == "Type" || key == "ID") {
@@ -1209,11 +1207,10 @@ int32_t CPDF_Creator::WriteDirectObj(FX_DWORD objnum,
       m_Offset += 2;
       const CPDF_Dictionary* p = pObj->AsDictionary();
       FX_BOOL bSignDict = IsSignatureDict(p);
-      FX_POSITION pos = p->GetStartPos();
-      while (pos) {
+      for (const auto& it : *p) {
         FX_BOOL bSignValue = FALSE;
-        CFX_ByteString key;
-        CPDF_Object* pValue = p->GetNextElement(pos, key);
+        const CFX_ByteString& key = it.first;
+        CPDF_Object* pValue = it.second;
         if (m_File.AppendString("/") < 0) {
           return -1;
         }
@@ -1786,10 +1783,9 @@ int32_t CPDF_Creator::WriteDoc_Stage4(IFX_Pause* pPause) {
     }
     if (m_pParser) {
       CPDF_Dictionary* p = m_pParser->m_pTrailer;
-      FX_POSITION pos = p->GetStartPos();
-      while (pos) {
-        CFX_ByteString key;
-        CPDF_Object* pValue = p->GetNextElement(pos, key);
+      for (const auto& it : *p) {
+        const CFX_ByteString& key = it.first;
+        CPDF_Object* pValue = it.second;
         if (key == "Encrypt" || key == "Size" || key == "Filter" ||
             key == "Index" || key == "Length" || key == "Prev" || key == "W" ||
             key == "XRefStm" || key == "ID") {