Rename IFWL classes which do not have CFWL equivalents

xfa/fwl/core/ifwl_formproxy.h

-// 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
-
-#ifndef XFA_FWL_CORE_IFWL_FORMPROXY_H_
-#define XFA_FWL_CORE_IFWL_FORMPROXY_H_
-
-#include <memory>
-
-#include "xfa/fwl/core/ifwl_form.h"
-
-class CFWL_WidgetProperties;
-
-class IFWL_FormProxy : public IFWL_Form {
- public:
-  IFWL_FormProxy(const CFWL_App* app,
-                 std::unique_ptr<CFWL_WidgetProperties> properties,
-                 IFWL_Widget* pOuter);
-  ~IFWL_FormProxy() override;
-
-  // IFWL_Widget
-  FWL_Type GetClassID() const override;
-  bool IsInstance(const CFX_WideStringC& wsClass) const override;
-  void Update() override;
-  void DrawWidget(CFX_Graphics* pGraphics,
-                  const CFX_Matrix* pMatrix = nullptr) override;
-  void OnProcessMessage(CFWL_Message* pMessage) override;
-};
-
-#endif  // XFA_FWL_CORE_IFWL_FORMPROXY_H_