Do not propagate empty value for face attribute

Source/core/html/HTMLFontElement.cpp

 /*
  * Copyright (C) 1999 Lars Knoll (knoll@kde.org)
  *           (C) 1999 Antti Koivisto (koivisto@kde.org)
  *           (C) 2000 Simon Hausmann <hausmann@kde.org>
  * Copyright (C) 2003, 2006, 2008, 2010 Apple 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 170 matching lines @@
 }
 
 void HTMLFontElement::collectStyleForPresentationAttribute(const QualifiedName& name, const AtomicString& value, MutableStylePropertySet* style)
 {
     if (name == sizeAttr) {
         CSSValueID size = CSSValueInvalid;
         if (cssValueFromFontSizeNumber(value, size))
             addPropertyToPresentationAttributeStyle(style, CSSPropertyFontSize, size);
     } else if (name == colorAttr)
         addHTMLColorToStyle(style, CSSPropertyColor, value);
-    else if (name == faceAttr) {
+    else if (name == faceAttr && !value.isEmpty()) {
         if (RefPtrWillBeRawPtr<CSSValueList> fontFaceValue = cssValuePool().createFontFaceValue(value))
             style->setProperty(CSSProperty(CSSPropertyFontFamily, fontFaceValue.release()));
     } else
         HTMLElement::collectStyleForPresentationAttribute(name, value, style);
 }
 
 }