Remove unused FWL Panel code.

xfa/fwl/basewidget/fwl_comboboximp.cpp

 // Copyright 2014 PDFium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 // Original code copyright 2014 Foxit Software Inc. http://www.foxitsoftware.com
 
 #include "xfa/fwl/basewidget/fwl_comboboximp.h"
 
 #include "xfa/fde/tto/fde_textout.h"
 #include "xfa/fwl/basewidget/fwl_editimp.h"
 #include "xfa/fwl/basewidget/fwl_formproxyimp.h"
 #include "xfa/fwl/basewidget/fwl_listboximp.h"
 #include "xfa/fwl/basewidget/fwl_scrollbarimp.h"
 #include "xfa/fwl/core/cfwl_message.h"
 #include "xfa/fwl/core/cfwl_themebackground.h"
 #include "xfa/fwl/core/cfwl_themepart.h"
 #include "xfa/fwl/core/cfwl_themetext.h"
 #include "xfa/fwl/core/fwl_appimp.h"
 #include "xfa/fwl/core/fwl_formimp.h"
 #include "xfa/fwl/core/fwl_noteimp.h"
-#include "xfa/fwl/core/fwl_panelimp.h"
 #include "xfa/fwl/core/fwl_targetimp.h"
 #include "xfa/fwl/core/fwl_threadimp.h"
 #include "xfa/fwl/core/fwl_widgetimp.h"
 #include "xfa/fwl/core/fwl_widgetmgrimp.h"
 #include "xfa/fwl/core/ifwl_themeprovider.h"
 #include "xfa/fwl/core/ifwl_thread.h"
 
 // static
 IFWL_ComboBox* IFWL_ComboBox::Create(
     const CFWL_WidgetImpProperties& properties) {
@@ skipping 1783 matching lines @@
   m_pComboBox->ShowDropList(FALSE);
 }
 void CFWL_ComboProxyImpDelegate::OnFocusChanged(CFWL_MsgKillFocus* pMsg,
                                                 FX_BOOL bSet) {
   if (!bSet) {
     if (pMsg->m_pSetFocus == NULL) {
       m_pComboBox->ShowDropList(FALSE);
     }
   }
 }