Clean up setting font-family: initial value.

Source/core/css/resolver/FontBuilder.h

 /*
  * Copyright (C) 1999 Lars Knoll (knoll@kde.org)
  * Copyright (C) 2003, 2004, 2005, 2006, 2007, 2008, 2009, 2010, 2011 Apple Inc. All rights reserved.
  * Copyright (C) 2013 Google Inc. All rights reserved.
  *
  * 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
  * version 2 of the License, or (at your option) any later version.
  *
@@ skipping 72 matching lines @@
     // FontBuilder calls at the callsite.
     void createFontForDocument(PassRefPtr<FontSelector>, RenderStyle*);
 
     bool fontSizeHasViewportUnits() { return m_fontSizehasViewportUnits; }
 
     // FIXME: These should not be necessary eventually.
     void setFontDirty(bool fontDirty) { m_fontDirty = fontDirty; }
     // FIXME: This is only used by an ASSERT in StyleResolver. Remove?
     bool fontDirty() const { return m_fontDirty; }
 
+    static FontDescription::GenericFamilyType initialGenericFamily() { return FontDescription::NoFamily; }
     static TextRenderingMode initialTextRendering() { return AutoTextRendering; }
     static FontVariant initialVariant() { return FontVariantNormal; }
     static FontStyle initialStyle() { return FontStyleNormal; }
     static FontDescription::Kerning initialKerning() { return FontDescription::AutoKerning; }
     static FontSmoothingMode initialFontSmoothing() { return AutoSmoothing; }
 
     friend class FontDescriptionChangeScope;
 
 private:
 
@@ skipping 22 matching lines @@
     // is changed, FontBuilder tracks the need to update
     // style->font() with this bool.
     bool m_fontDirty;
 
     friend class FontBuilderTest;
 };
 
 }
 
 #endif