Use removeFontFace to avoid resetting fontSelector.

Source/core/dom/StyleEngine.h

 /*
  * Copyright (C) 1999 Lars Knoll (knoll@kde.org)
  *           (C) 1999 Antti Koivisto (koivisto@kde.org)
  *           (C) 2001 Dirk Mueller (mueller@kde.org)
  *           (C) 2006 Alexey Proskuryakov (ap@webkit.org)
  * Copyright (C) 2004, 2005, 2006, 2007, 2008, 2009, 2010, 2012 Apple Inc. All rights reserved.
  * Copyright (C) 2008, 2009 Torch Mobile Inc. All rights reserved. (http://www.torchmobile.com/)
  * Copyright (C) 2010 Nokia Corporation and/or its subsidiary(-ies)
  * Copyright (C) 2011 Google Inc. All rights reserved.
  *
@@ skipping 31 matching lines @@
 
 namespace WebCore {
 
 class CSSFontSelector;
 class CSSStyleSheet;
 class FontSelector;
 class Node;
 class RuleFeatureSet;
 class ShadowTreeStyleSheetCollection;
 class StyleResolver;
+class StyleRuleFontFace;
 class StyleSheet;
 class StyleSheetCollection;
 class StyleSheetContents;
 class StyleSheetList;
 
 class StyleResolverChange {
 public:
     StyleResolverChange()
         : m_needsRepaint(false)
         , m_needsStyleRecalc(false)
@@ skipping 95 matching lines @@
             m_resolver->appendPendingAuthorStyleSheets();
         }
         return *m_resolver.get();
     }
 
     bool hasResolver() const { return m_resolver.get(); }
     void clearResolver();
     void clearMasterResolver();
 
     CSSFontSelector* fontSelector() { return m_fontSelector.get(); }
+    void removeFontFaceRules(const Vector<const StyleRuleFontFace*>&);
+    // FIXME: still need to use resetFontSelector when GenericFontFamilySettings is changed.
     void resetFontSelector();
 
     void didAttach();
     void didDetach();
     bool shouldClearResolver() const;
     StyleResolverChange resolverChanged(RecalcStyleTime, StyleResolverUpdateMode);
     unsigned resolverAccessCount() const;
 
     void collectDocumentActiveStyleSheets(StyleSheetCollectionBase&);
     void markDocumentDirty() { m_dirtyTreeScopes.markDocument(); }
@@ skipping 56 matching lines @@
     unsigned m_lastResolverAccessCount;
     Timer<StyleEngine> m_resolverThrowawayTimer;
     OwnPtr<StyleResolver> m_resolver;
 
     RefPtr<CSSFontSelector> m_fontSelector;
 };
 
 }
 
 #endif