Update typesetting features when letter-spacing is changed.

Source/platform/fonts/FontDescription.h

 /*
  * Copyright (C) 2000 Lars Knoll (knoll@kde.org)
  *           (C) 2000 Antti Koivisto (koivisto@kde.org)
  *           (C) 2000 Dirk Mueller (mueller@kde.org)
  * Copyright (C) 2003, 2004, 2005, 2006, 2007, 2008 Apple Inc. All rights reserved.
  * Copyright (C) 2007 Nicholas Shanks <webkit@nickshanks.com>
  *
  * 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
@@ skipping 183 matching lines @@
     void setOrientation(FontOrientation orientation) { m_orientation = orientation; }
     void setNonCJKGlyphOrientation(NonCJKGlyphOrientation orientation) { m_nonCJKGlyphOrientation = orientation; }
     void setWidthVariant(FontWidthVariant widthVariant) { m_widthVariant = widthVariant; }
     void setScript(UScriptCode s) { m_script = s; }
     void setLocale(const String& locale) { m_locale = locale; }
     void setSyntheticBold(bool syntheticBold) { m_syntheticBold = syntheticBold; }
     void setSyntheticItalic(bool syntheticItalic) { m_syntheticItalic = syntheticItalic; }
     void setFeatureSettings(PassRefPtr<FontFeatureSettings> settings) { m_featureSettings = settings; }
     void setTraits(FontTraits);
     void setWordSpacing(float s) { m_wordSpacing = s; }
-    void setLetterSpacing(float s) { m_letterSpacing = s; }
+    void setLetterSpacing(float s) { m_letterSpacing = s; updateTypesettingFeatures(); }
 
     TypesettingFeatures typesettingFeatures() const { return static_cast<TypesettingFeatures>(m_typesettingFeatures); }
 
     static void setSubpixelPositioning(bool b) { s_useSubpixelTextPositioning = b; }
     static bool subpixelPositioning() { return s_useSubpixelTextPositioning; }
 
     static void setDefaultTypesettingFeatures(TypesettingFeatures);
     static TypesettingFeatures defaultTypesettingFeatures();
 
 private:
@@ skipping 75 matching lines @@
         && m_script == other.m_script
         && m_syntheticBold == other.m_syntheticBold
         && m_syntheticItalic == other.m_syntheticItalic
         && m_featureSettings == other.m_featureSettings
         && m_subpixelTextPosition == other.m_subpixelTextPosition;
 }
 
 } // namespace blink
 
 #endif