Remove include only fwl.h and IWYU.

xfa/src/fwl/src/lightwidget/pushbutton.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/include/fwl/lightwidget/pushbutton.h"
+
 #include <memory>
 
 #include "xfa/src/foxitlib.h"
 
 CFWL_PushButton* CFWL_PushButton::Create() {
   return new CFWL_PushButton;
 }
 FWL_ERR CFWL_PushButton::Initialize(const CFWL_WidgetProperties* pProperties) {
   if (m_pIface)
     return FWL_ERR_Indefinite;
@@ skipping 30 matching lines @@
 FWL_ERR CFWL_PushButton::CFWL_PushButtonDP::GetCaption(
     IFWL_Widget* pWidget,
     CFX_WideString& wsCaption) {
   wsCaption = m_wsCaption;
   return FWL_ERR_Succeeded;
 }
 CFX_DIBitmap* CFWL_PushButton::CFWL_PushButtonDP::GetPicture(
     IFWL_Widget* pWidget) {
   return m_pBitmap;
 }