Make down-conversion explicit from CFX_ByteString to CFX_ByteStringC.

core/fpdfapi/fpdf_font/fpdf_font_cid.cpp

Index: core/fpdfapi/fpdf_font/fpdf_font_cid.cpp
diff --git a/core/fpdfapi/fpdf_font/fpdf_font_cid.cpp b/core/fpdfapi/fpdf_font/fpdf_font_cid.cpp
index 2552a3c0a63d60e302cc368d35905436564265bc..fb3707f498b23758eacd34886eb0e2a6f58aa67d 100644
--- a/core/fpdfapi/fpdf_font/fpdf_font_cid.cpp
+++ b/core/fpdfapi/fpdf_font/fpdf_font_cid.cpp
@@ -440,7 +440,7 @@ void CPDF_CMapParser::ParseWord(const CFX_ByteStringC& word) {
       }
       if (m_CodeSeq % 2) {
         CMap_CodeRange range;
-        if (CMap_GetCodeRange(range, m_LastWord, word)) {
+        if (CMap_GetCodeRange(range, m_LastWord.AsByteStringC(), word)) {
           m_CodeRanges.Add(range);
         }
       }