Clean up forward declarations in Source/platform

Source/platform/fonts/FontCache.h

 /*
  * Copyright (C) 2006, 2008 Apple Computer, Inc.  All rights reserved.
  * Copyright (C) 2007-2008 Torch Mobile, Inc.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions
  * are met:
  *
  * 1.  Redistributions of source code must retain the above copyright
  *     notice, this list of conditions and the following disclaimer.
@@ skipping 42 matching lines @@
 #include <unicode/uscript.h>
 #endif
 
 class SkTypeface;
 
 namespace blink {
 
 class FontCacheClient;
 class FontFaceCreationParams;
 class FontPlatformData;
-class FontData;
 class FontDescription;
 class OpenTypeVerticalData;
 class SimpleFontData;
 
 enum ShouldRetain { Retain, DoNotRetain };
 enum PurgeSeverity { PurgeIfNeeded, ForcePurge };
 
 class PLATFORM_EXPORT FontCache {
     friend class FontCachePurgePreventer;
 
@@ skipping 102 matching lines @@
 
 class PLATFORM_EXPORT FontCachePurgePreventer {
 public:
     FontCachePurgePreventer() { FontCache::fontCache()->disablePurging(); }
     ~FontCachePurgePreventer() { FontCache::fontCache()->enablePurging(); }
 };
 
 } // namespace blink
 
 #endif