Trim FontSelector interface a bit.

Source/core/css/CSSFontSelector.h

Index: Source/core/css/CSSFontSelector.h
diff --git a/Source/core/css/CSSFontSelector.h b/Source/core/css/CSSFontSelector.h
index b767ea85596df42d54904a08f51547cc917ba90b..eb9f80aec6a34ee2b7c3c0a32b3d997d33a12e9b 100644
--- a/Source/core/css/CSSFontSelector.h
+++ b/Source/core/css/CSSFontSelector.h
@@ -39,6 +39,7 @@ namespace WebCore {
 
 class CSSFontFace;
 class CSSFontFaceRule;
+class CSSFontSelectorClient;
 class CSSSegmentedFontFace;
 class FontResource;
 class Document;
@@ -81,10 +82,12 @@ public:
     void removeFontFaceRule(const StyleRuleFontFace*);
 
     void fontLoaded();
+
+    // FontCacheClient implementation
     virtual void fontCacheInvalidated() OVERRIDE;
 
-    virtual void registerForInvalidationCallbacks(FontSelectorClient*) OVERRIDE;
-    virtual void unregisterForInvalidationCallbacks(FontSelectorClient*) OVERRIDE;
+    void registerForInvalidationCallbacks(CSSFontSelectorClient*);
+    void unregisterForInvalidationCallbacks(CSSFontSelectorClient*);
 
     Document* document() const { return m_document; }
     CSSSegmentedFontFaceCache* cssSegmentedFontFaceCache() { return &m_cssSegmentedFontFaceCache; }
@@ -102,7 +105,7 @@ private:
     Document* m_document;
     // FIXME: Move to Document or StyleEngine.
     CSSSegmentedFontFaceCache m_cssSegmentedFontFaceCache;
-    HashSet<FontSelectorClient*> m_clients;
+    HashSet<CSSFontSelectorClient*> m_clients;
 
     FontLoader m_fontLoader;
     GenericFontFamilySettings m_genericFontFamilySettings;