Continue nit cleanup in fwl/core

xfa/fwl/core/cfwl_combobox.cpp

Index: xfa/fwl/core/cfwl_combobox.cpp
diff --git a/xfa/fwl/core/cfwl_combobox.cpp b/xfa/fwl/core/cfwl_combobox.cpp
index a8211e9773d5920bf10e856da1d12208b2ae07aa..fcdbec948959df876b850d8cdd8e3b88bf723ab3 100644
--- a/xfa/fwl/core/cfwl_combobox.cpp
+++ b/xfa/fwl/core/cfwl_combobox.cpp
@@ -18,10 +18,6 @@ IFWL_ComboBox* ToComboBox(IFWL_Widget* widget) {
   return static_cast<IFWL_ComboBox*>(widget);
 }
 
-const IFWL_ComboBox* ToComboBox(const IFWL_Widget* widget) {
-  return static_cast<const IFWL_ComboBox*>(widget);
-}
-
 }  // namespace
 
 CFWL_ComboBox::CFWL_ComboBox(const IFWL_App* app)