Clean up setting font-family: initial value.

Source/core/css/resolver/FontBuilder.h

Index: Source/core/css/resolver/FontBuilder.h
diff --git a/Source/core/css/resolver/FontBuilder.h b/Source/core/css/resolver/FontBuilder.h
index 3057f32cc986b5693715dcf150c9a8bc312b9dee..86d042306636468931e2f6780360c6c0c2c7134b 100644
--- a/Source/core/css/resolver/FontBuilder.h
+++ b/Source/core/css/resolver/FontBuilder.h
@@ -90,6 +90,7 @@ public:
     // 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; }