Make down-conversion explicit from CFX_Widetring to CFX_WideStringC.

xfa/fwl/core/fwl_formimp.cpp

Index: xfa/fwl/core/fwl_formimp.cpp
diff --git a/xfa/fwl/core/fwl_formimp.cpp b/xfa/fwl/core/fwl_formimp.cpp
index f7fc301d979759fab5f97cb8e117c19b2229a76e..5a5cc5e59bb74f09887c8c1769799a8f2bc9df65 100644
--- a/xfa/fwl/core/fwl_formimp.cpp
+++ b/xfa/fwl/core/fwl_formimp.cpp
@@ -822,7 +822,7 @@ void CFWL_FormImp::UpdateCaption() {
     return;
   CFX_WideString text;
   pData->GetCaption(m_pInterface, text);
-  pWidgetMgr->SetWidgetCaption_Native(m_pInterface, text);
+  pWidgetMgr->SetWidgetCaption_Native(m_pInterface, text.AsWideStringC());
 }
 void CFWL_FormImp::DoWidthLimit(FX_FLOAT& fLeft,
                                 FX_FLOAT& fWidth,