Remove unused FWL Panel code.

xfa/fwl/core/fwl_panelimp.h

Index: xfa/fwl/core/fwl_panelimp.h
diff --git a/xfa/fwl/core/fwl_panelimp.h b/xfa/fwl/core/fwl_panelimp.h
deleted file mode 100644
index 34e236da1af3cbc5a4456f5579d69e63fe962332..0000000000000000000000000000000000000000
--- a/xfa/fwl/core/fwl_panelimp.h
+++ /dev/null
@@ -1,27 +0,0 @@
-// 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_FWL_PANELIMP_H_
-#define XFA_FWL_CORE_FWL_PANELIMP_H_
-
-#include "xfa/fwl/core/fwl_widgetimp.h"
-
-class CFWL_WidgetImpProperties;
-class IFWL_Widget;
-class IFWL_Content;
-
-class CFWL_PanelImp : public CFWL_WidgetImp {
- public:
-  CFWL_PanelImp(const CFWL_WidgetImpProperties& properties,
-                IFWL_Widget* pOuter);
-  virtual ~CFWL_PanelImp();
-
-  virtual FWL_ERR GetClassName(CFX_WideString& wsClass) const;
-  virtual uint32_t GetClassID() const;
-  virtual FWL_ERR GetWidgetRect(CFX_RectF& rect, FX_BOOL bAutoSize = FALSE);
-};
-
-#endif  // XFA_FWL_CORE_FWL_PANELIMP_H_