Make CFX_WideString(const CFX_WideString&) explicit.

xfa/fgas/localization/fgas_localemgr.cpp

Index: xfa/fgas/localization/fgas_localemgr.cpp
diff --git a/xfa/fgas/localization/fgas_localemgr.cpp b/xfa/fgas/localization/fgas_localemgr.cpp
index 93e5ea08744757ef14bbd74c128ed67c20ea6c52..e0ce8d91272042f34087ed0d4f9e73d3b020f45e 100644
--- a/xfa/fgas/localization/fgas_localemgr.cpp
+++ b/xfa/fgas/localization/fgas_localemgr.cpp
@@ -91,7 +91,6 @@ IFX_Locale* CFX_LocaleMgr::GetLocale(uint16_t lcid) {
   }
   return pLocale;
 }
-IFX_Locale* CFX_LocaleMgr::GetLocaleByName(
-    const CFX_WideStringC& wsLocaleName) {
-  return NULL;
+IFX_Locale* CFX_LocaleMgr::GetLocaleByName(const CFX_WideString& wsLocaleName) {
+  return nullptr;
 }