Convert CXFA_Node::GetLocaleName out param to return

Change-Id: Ia135db144c7037795fc1a1964b4f3eee57250caa
Reviewed-on: https://pdfium-review.googlesource.com/22350
Commit-Queue: Ryan Harrison <rharrison@chromium.org>
Reviewed-by: Henrique Nakashima <hnakashima@chromium.org>
diff --git a/fxjs/xfa/cjx_subform.cpp b/fxjs/xfa/cjx_subform.cpp
index a388505..947d66d 100644
--- a/fxjs/xfa/cjx_subform.cpp
+++ b/fxjs/xfa/cjx_subform.cpp
@@ -86,8 +86,7 @@
     return;
   }
 
-  WideString wsLocaleName;
-  GetXFANode()->GetLocaleName(wsLocaleName);
+  WideString wsLocaleName = GetXFANode()->GetLocaleName().value_or(L"");
   pValue->SetString(wsLocaleName.UTF8Encode().AsStringView());
 }