Cleanup some PWL interfaces.

fpdfsdk/formfiller/cffl_combobox.cpp

Index: fpdfsdk/formfiller/cffl_combobox.cpp
diff --git a/fpdfsdk/formfiller/cffl_combobox.cpp b/fpdfsdk/formfiller/cffl_combobox.cpp
index 262c485138a8d5719c60cc3cdb70e87a753ec4b8..4b8473389069363ccbcfb0692331c3e8591164d9 100644
--- a/fpdfsdk/formfiller/cffl_combobox.cpp
+++ b/fpdfsdk/formfiller/cffl_combobox.cpp
@@ -267,19 +267,9 @@ void CFFL_ComboBox::OnSetFocus(CPWL_Wnd* pWnd) {
     unsigned short* pBuffer = (unsigned short*)bsUTFText.c_str();
     m_pApp->FFI_OnSetFieldInputFocus(m_pWidget->GetFormField(), pBuffer,
                                      nCharacters, TRUE);
-
-    pEdit->SetEditNotify(this);
   }
 }
 
-void CFFL_ComboBox::OnKillFocus(CPWL_Wnd* pWnd) {
-  ASSERT(m_pApp);
-}
-
-void CFFL_ComboBox::OnAddUndo(CPWL_Edit* pEdit) {
-  ASSERT(pEdit);
-}
-
 CFX_WideString CFFL_ComboBox::GetSelectExportText() {
   CFX_WideString swRet;