Make down-conversion explicit from CFX_ByteString to CFX_ByteStringC.

fpdfsdk/fxedit/fxet_pageobjs.cpp

Index: fpdfsdk/fxedit/fxet_pageobjs.cpp
diff --git a/fpdfsdk/fxedit/fxet_pageobjs.cpp b/fpdfsdk/fxedit/fxet_pageobjs.cpp
index 3f32d9d3e1fbacf504299d965b080da08a47a470..1133cab7967e735e35a354c827bcdab7ab9bedd3 100644
--- a/fpdfsdk/fxedit/fxet_pageobjs.cpp
+++ b/fpdfsdk/fxedit/fxet_pageobjs.cpp
@@ -246,7 +246,8 @@ void IFX_Edit::DrawEdit(CFX_RenderDevice* pDevice,
             }
 
             sTextBuf << GetPDFWordString(pFontMap, word.nFontIndex, word.Word,
-                                         SubWord);
+                                         SubWord)
+                            .AsByteStringC();
           } else {
             DrawTextString(
                 pDevice, CFX_FloatPoint(word.ptWord.x + ptOffset.x,
@@ -359,7 +360,8 @@ void IFX_Edit::DrawRichEdit(CFX_RenderDevice* pDevice,
           }
 
           sTextBuf << GetPDFWordString(pFontMap, word.WordProps.nFontIndex,
-                                       word.Word, 0);
+                                       word.Word, 0)
+                          .AsByteStringC();
 
           if (word.WordProps.nWordStyle & PVTWORD_STYLE_UNDERLINE) {
             CFX_PathData pathUnderline;
@@ -502,7 +504,8 @@ void IFX_Edit::GeneratePageObjects(
             nOldFontIndex = word.nFontIndex;
           }
 
-          sTextBuf << GetPDFWordString(pFontMap, word.nFontIndex, word.Word, 0);
+          sTextBuf << GetPDFWordString(pFontMap, word.nFontIndex, word.Word, 0)
+                          .AsByteStringC();
           oldplace = place;
         }
       }
@@ -574,7 +577,8 @@ void IFX_Edit::GenerateRichPageObjects(
           }
 
           sTextBuf << GetPDFWordString(pFontMap, word.WordProps.nFontIndex,
-                                       word.Word, 0);
+                                       word.Word, 0)
+                          .AsByteStringC();
 
           if (word.WordProps.nWordStyle & PVTWORD_STYLE_UNDERLINE) {
             CFX_FloatRect rcUnderline = GetUnderLineRect(word);