Use removeFontFace to avoid resetting fontSelector.

Source/core/dom/StyleEngine.cpp

 /*
  * 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, 2011, 2012 Apple Inc. All rights reserved.
  * Copyright (C) 2008, 2009 Torch Mobile Inc. All rights reserved. (http://www.torchmobile.com/)
  * Copyright (C) 2008, 2009, 2011, 2012 Google Inc. All rights reserved.
  * Copyright (C) 2010 Nokia Corporation and/or its subsidiary(-ies)
  * Copyright (C) Research In Motion Limited 2010-2011. All rights reserved.
@@ skipping 554 matching lines @@
     // CSSFontSelector.
     if (m_document.isActive()) {
         m_fontSelector = CSSFontSelector::create(&m_document);
         if (m_resolver)
             m_fontSelector->registerForInvalidationCallbacks(m_resolver.get());
     } else {
         m_fontSelector = 0;
     }
 }
 
+void StyleEngine::removeFontFaceRules(const Vector<const StyleRuleFontFace*>& fontFaceRules)
+{
+    if (!m_fontSelector)
+        return;
+    for (unsigned i = 0; i < fontFaceRules.size(); ++i)
+        m_fontSelector->removeFontFaceRule(fontFaceRules[i]);
+    if (m_resolver)
+        m_resolver->invalidateMatchedPropertiesCache();
 }
+
+}