Reduce number of header includes in SVG

Source/core/svg/SVGFontData.h

 /*
  * Copyright (C) 2008 Nikolas Zimmermann <zimmermann@kde.org>
  *
  * This library is free software; you can redistribute it and/or
  * modify it under the terms of the GNU Library General Public
  * License as published by the Free Software Foundation; either
  * version 2 of the License, or (at your option) any later version.
  *
  * This library is distributed in the hope that it will be useful,
  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  * Library General Public License for more details.
  *
  * You should have received a copy of the GNU Library General Public License
  * along with this library; see the file COPYING.LIB.  If not, write to
  * the Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor,
  * Boston, MA 02110-1301, USA.
  */
 
 #ifndef SVGFontData_h
 #define SVGFontData_h
 
 #if ENABLE(SVG_FONTS)
 #include "core/platform/graphics/SimpleFontData.h"
-#include "core/svg/SVGFontFaceElement.h"
 
 namespace WebCore {
 
+class SVGFontElement;
+class SVGFontFaceElement;
+
 class SVGFontData : public SimpleFontData::AdditionalFontData {
 public:
     static PassOwnPtr<SVGFontData> create(SVGFontFaceElement* element)
     {
         return adoptPtr(new SVGFontData(element));
     }
 
     virtual ~SVGFontData() { }
 
     virtual void initializeFontData(SimpleFontData*, float fontSize);
@@ skipping 33 matching lines @@
 
     float m_verticalOriginX;
     float m_verticalOriginY;
     float m_verticalAdvanceY;
 };
 
 } // namespace WebCore
 
 #endif
 #endif // SVGFontData_h