Make down-conversion explicit from CFX_ByteString to CFX_ByteStringC.

xfa/fwl/basewidget/fwl_editimp.cpp

Index: xfa/fwl/basewidget/fwl_editimp.cpp
diff --git a/xfa/fwl/basewidget/fwl_editimp.cpp b/xfa/fwl/basewidget/fwl_editimp.cpp
index d5aa2c0507fb471800fa78537d70e04baf81752a..008936c90e097e3f32b1da0765a2e21e55e55443 100644
--- a/xfa/fwl/basewidget/fwl_editimp.cpp
+++ b/xfa/fwl/basewidget/fwl_editimp.cpp
@@ -734,14 +734,14 @@ FX_BOOL CFWL_EditImp::Undo() {
     return FALSE;
   }
   CFX_ByteString bsRecord = m_RecordArr[m_iCurRecord--];
-  return Undo(bsRecord);
+  return Undo(bsRecord.AsByteStringC());
 }
 FX_BOOL CFWL_EditImp::Redo() {
   if (!CanRedo()) {
     return FALSE;
   }
   CFX_ByteString bsRecord = m_RecordArr[++m_iCurRecord];
-  return Redo(bsRecord);
+  return Redo(bsRecord.AsByteStringC());
 }
 FX_BOOL CFWL_EditImp::CanUndo() {
   return m_iCurRecord >= 0;