Change IFWL_Widget to store a single delegate.

xfa/fwl/core/ifwl_form.cpp

Index: xfa/fwl/core/ifwl_form.cpp
diff --git a/xfa/fwl/core/ifwl_form.cpp b/xfa/fwl/core/ifwl_form.cpp
index 125f7c4cab46a46884dbc2456bd2970ec4239e69..0004c24a96fd914d7f7c75239c194830384f0e51 100644
--- a/xfa/fwl/core/ifwl_form.cpp
+++ b/xfa/fwl/core/ifwl_form.cpp
@@ -821,8 +821,7 @@ void CFWL_FormImpDelegate::OnProcessMessage(CFWL_Message* pMessage) {
         if (pSubFocus == pDriver->GetFocus()) {
           pDriver->SetFocus(nullptr);
         } else if (pSubFocus->GetStates() & FWL_WGTSTATE_Focused) {
-          if (IFWL_WidgetDelegate* pDelegate =
-                  pSubFocus->GetCurrentDelegate()) {
+          if (IFWL_WidgetDelegate* pDelegate = pSubFocus->GetDelegate()) {
             CFWL_MsgKillFocus ms;
             pDelegate->OnProcessMessage(&ms);
           }