Fix some iterator invalidation issues while traversing CPDF_Dictionary.

core/src/fpdfapi/fpdf_page/fpdf_page_parser.cpp

Index: core/src/fpdfapi/fpdf_page/fpdf_page_parser.cpp
diff --git a/core/src/fpdfapi/fpdf_page/fpdf_page_parser.cpp b/core/src/fpdfapi/fpdf_page/fpdf_page_parser.cpp
index d3e3807046fa7a9ec5a7ecb89904c586c3809b85..7091b207ffbbefe85c1507dd00355746aa5b947d 100644
--- a/core/src/fpdfapi/fpdf_page/fpdf_page_parser.cpp
+++ b/core/src/fpdfapi/fpdf_page/fpdf_page_parser.cpp
@@ -496,9 +496,11 @@ void PDF_ReplaceAbbr(CPDF_Object* pObj) {
   switch (pObj->GetType()) {
     case PDFOBJ_DICTIONARY: {
       CPDF_Dictionary* pDict = pObj->AsDictionary();
-      for (const auto& it : *pDict) {
-        CFX_ByteString key = it.first;
-        CPDF_Object* value = it.second;
+      auto it = pDict->begin();
+      while (it != pDict->end()) {
+        auto old_it = it++;
+        CFX_ByteString key = old_it->first;
+        CPDF_Object* value = old_it->second;
         CFX_ByteStringC fullname = PDF_FindFullName(
             PDF_InlineKeyAbbr, FX_ArraySize(PDF_InlineKeyAbbr), key);
         if (!fullname.IsEmpty()) {
@@ -543,9 +545,11 @@ void PDF_ReplaceFull(CPDF_Object* pObj) {
   switch (pObj->GetType()) {
     case PDFOBJ_DICTIONARY: {
       CPDF_Dictionary* pDict = pObj->AsDictionary();
-      for (const auto& it : *pDict) {
-        CFX_ByteString key = it.first;
-        CPDF_Object* value = it.second;
+      auto it = pDict->begin();
+      while (it != pDict->end()) {
+        auto old_it = it++;
+        CFX_ByteString key = old_it->first;
+        CPDF_Object* value = old_it->second;
         CFX_ByteStringC abbrName = PDF_FindAbbrName(
             PDF_InlineKeyAbbr, FX_ArraySize(PDF_InlineKeyAbbr), key);
         if (!abbrName.IsEmpty()) {