Clean up forward declarations in Source/platform

Source/platform/fonts/SimpleFontData.h

 /*
  * This file is part of the internal font implementation.
  *
  * Copyright (C) 2006, 2008, 2010 Apple Inc. All rights reserved.
  * Copyright (C) 2007-2008 Torch Mobile, Inc.
  *
  * 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 27 matching lines @@
 #include "wtf/OwnPtr.h"
 #include "wtf/PassOwnPtr.h"
 #include "wtf/text/StringHash.h"
 
 #if OS(MACOSX)
 #include "wtf/RetainPtr.h"
 #endif
 
 namespace blink {
 
-class CSSFontFaceSource;
 class FontDescription;
-class SharedBuffer;
-struct WidthIterator;
 
 enum FontDataVariant { AutoVariant, NormalVariant, SmallCapsVariant, EmphasisMarkVariant, BrokenIdeographVariant };
 enum Pitch { UnknownPitch, FixedPitch, VariablePitch };
 
 class PLATFORM_EXPORT SimpleFontData : public FontData {
 public:
     // Used to create platform fonts.
     static PassRefPtr<SimpleFontData> create(const FontPlatformData& platformData, PassRefPtr<CustomFontData> customData = nullptr, bool isTextOrientationFallback = false)
     {
         return adoptRef(new SimpleFontData(platformData, customData, isTextOrientationFallback));
@@ skipping 226 matching lines @@
         width = platformWidthForGlyph(glyph);
 
     m_glyphToWidthMap.setMetricsForGlyph(glyph, width);
     return width;
 }
 
 DEFINE_FONT_DATA_TYPE_CASTS(SimpleFontData, false);
 
 } // namespace blink
 #endif // SimpleFontData_h