Make down-conversion explicit from CFX_ByteString to CFX_ByteStringC.

core/fxge/win32/fx_win32_device.cpp

Index: core/fxge/win32/fx_win32_device.cpp
diff --git a/core/fxge/win32/fx_win32_device.cpp b/core/fxge/win32/fx_win32_device.cpp
index cb3f331d495ffb91b6a8670d782bca66156e8e54..ed57a02c23eabcddf8500f169ed4171df9f89a38 100644
--- a/core/fxge/win32/fx_win32_device.cpp
+++ b/core/fxge/win32/fx_win32_device.cpp
@@ -460,7 +460,7 @@ IFX_SystemFontInfo* IFX_SystemFontInfo::CreateDefault(const char** pUnused) {
   if (path_len > 0 && path_len < MAX_PATH) {
     CFX_ByteString fonts_path(windows_path);
     fonts_path += "\\Fonts";
-    pInfoFallback->AddPath(fonts_path);
+    pInfoFallback->AddPath(fonts_path.AsByteStringC());
   }
   return pInfoFallback;
 }