Reduce forward declarations in core/svg

Source/core/svg/SVGFontElement.h

 /*
  * Copyright (C) 2007 Eric Seidel <eric@webkit.org>
  * Copyright (C) 2007 Nikolas Zimmermann <zimmermann@kde.org>
  * Copyright (C) Research In Motion Limited 2010. All rights reserved.
  *
  * 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.
  *
@@ skipping 33 matching lines @@
     SVGKerningPair()
         : kerning(0)
     {
     }
 };
 
 typedef unsigned KerningPairKey;
 typedef Vector<SVGKerningPair> KerningPairVector;
 typedef HashMap<KerningPairKey, float> KerningTable;
 
-class SVGMissingGlyphElement;
-
 class SVGFontElement FINAL : public SVGElement {
 public:
     DECLARE_NODE_FACTORY(SVGFontElement);
 
     void invalidateGlyphCache();
     void collectGlyphsForString(const String&, Vector<SVGGlyph>&);
     void collectGlyphsForAltGlyphReference(const String&, Vector<SVGGlyph>&);
 
     float horizontalKerningForPairOfGlyphs(Glyph, Glyph) const;
     float verticalKerningForPairOfGlyphs(Glyph, Glyph) const;
@@ skipping 18 matching lines @@
     KerningTable m_verticalKerningTable;
     SVGGlyphMap m_glyphMap;
     Glyph m_missingGlyph;
     bool m_isGlyphCacheValid;
 };
 
 } // namespace WebCore
 
 #endif // ENABLE(SVG_FONTS)
 #endif