Update typesetting features when letter-spacing is changed.

Source/platform/fonts/FontDescription.h

Index: Source/platform/fonts/FontDescription.h
diff --git a/Source/platform/fonts/FontDescription.h b/Source/platform/fonts/FontDescription.h
index f736b52867fcd744493a643c250d152edcd8f4c6..263e583509c9419a77f794601857037a4992f37a 100644
--- a/Source/platform/fonts/FontDescription.h
+++ b/Source/platform/fonts/FontDescription.h
@@ -201,7 +201,7 @@ public:
     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); }