Remove FontDescriptionChangeScope, and let FontBuilder partially apply values.

Source/core/dom/Document.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 1646 matching lines @@
         root = host;
     while (Node* ancestor = root->parentOrShadowHostNode())
         root = ancestor;
     if (root->childNeedsDistributionRecalc())
         root->recalcDistribution();
 }
 
 void Document::setupFontBuilder(RenderStyle* documentStyle)
 {
     FontBuilder fontBuilder(*this);
-    fontBuilder.setFontDescription(documentStyle->fontDescription());
     RefPtrWillBeRawPtr<CSSFontSelector> selector = m_styleEngine->fontSelector();
     fontBuilder.createFontForDocument(selector, documentStyle);
 }
 
 void Document::inheritHtmlAndBodyElementStyles(StyleRecalcChange change)
 {
     ASSERT(inStyleRecalc());
     ASSERT(documentElement());
 
     RefPtr<RenderStyle> documentElementStyle = documentElement()->renderStyle();
@@ skipping 4167 matching lines @@
 #ifndef NDEBUG
 using namespace blink;
 void showLiveDocumentInstances()
 {
     WeakDocumentSet& set = liveDocumentSet();
     fprintf(stderr, "There are %u documents currently alive:\n", set.size());
     for (Document* document : set)
         fprintf(stderr, "- Document %p URL: %s\n", document, document->url().string().utf8().data());
 }
 #endif