Remove FontDescriptionChangeScope, and let FontBuilder partially apply values.

Source/core/css/resolver/StyleResolverState.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.
  *
  * 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.
  *
  * This library is distributed in the hope that it will be useful,
@@ skipping 48 matching lines @@
     EInsideLink elementLinkState() const { return m_elementContext.elementLinkState(); }
     bool distributedToInsertionPoint() const { return m_elementContext.distributedToInsertionPoint(); }
 
     const ElementResolveContext& elementContext() const { return m_elementContext; }
 
     void setStyle(PassRefPtr<RenderStyle> style)
     {
         // FIXME: Improve RAII of StyleResolverState to remove this function.
         m_style = style;
         m_cssToLengthConversionData = CSSToLengthConversionData(m_style.get(), rootElementStyle(), document().renderView(), m_style->effectiveZoom());
-        m_fontBuilder.setFontDescription(m_style->fontDescription());
     }
     const RenderStyle* style() const { return m_style.get(); }
     RenderStyle* style() { return m_style.get(); }
     PassRefPtr<RenderStyle> takeStyle() { return m_style.release(); }
 
     const CSSToLengthConversionData& cssToLengthConversionData() const { return m_cssToLengthConversionData; }
 
     void setConversionFontSizes(const CSSToLengthConversionData::FontSizes& fontSizes) { m_cssToLengthConversionData.setFontSizes(fontSizes); }
     void setConversionZoom(float zoom) { m_cssToLengthConversionData.setZoom(zoom); }
 
@@ skipping 40 matching lines @@
         return m_elementStyleResources.styleImage(document(), document().textLinkColors(), style()->color(), propertyId, value);
     }
 
     FontBuilder& fontBuilder() { return m_fontBuilder; }
     // FIXME: These exist as a primitive way to track mutations to font-related properties
     // on a RenderStyle. As designed, these are very error-prone, as some callers
     // set these directly on the RenderStyle w/o telling us. Presumably we'll
     // want to design a better wrapper around RenderStyle for tracking these mutations
     // and separate it from StyleResolverState.
     const FontDescription& parentFontDescription() { return m_parentStyle->fontDescription(); }
-    void setZoom(float f) { m_fontBuilder.didChangeFontParameters(m_style->setZoom(f)); }
-    void setEffectiveZoom(float f) { m_fontBuilder.didChangeFontParameters(m_style->setEffectiveZoom(f)); }
-    void setWritingMode(WritingMode writingMode) { m_fontBuilder.didChangeFontParameters(m_style->setWritingMode(writingMode)); }
-    void setTextOrientation(TextOrientation textOrientation) { m_fontBuilder.didChangeFontParameters(m_style->setTextOrientation(textOrientation)); }
+
+    void setZoom(float f)
+    {
+        if (m_style->setZoom(f))
+            m_fontBuilder.didChangeEffectiveZoom();
+    }
+    void setEffectiveZoom(float f)
+    {
+        if (m_style->setEffectiveZoom(f))
+            m_fontBuilder.didChangeEffectiveZoom();
+    }
+    void setWritingMode(WritingMode writingMode)
+    {
+        if (m_style->setWritingMode(writingMode))
+            m_fontBuilder.didChangeWritingMode();
+    }
+    void setTextOrientation(TextOrientation textOrientation)
+    {
+        if (m_style->setTextOrientation(textOrientation))
+            m_fontBuilder.didChangeTextOrientation();
+    }
 
 private:
     ElementResolveContext m_elementContext;
     RawPtrWillBeMember<Document> m_document;
 
     // m_style is the primary output for each element's style resolve.
     RefPtr<RenderStyle> m_style;
 
     CSSToLengthConversionData m_cssToLengthConversionData;
 
     // m_parentStyle is not always just ElementResolveContext::parentStyle,
     // so we keep it separate.
     RefPtr<RenderStyle> m_parentStyle;
 
     OwnPtrWillBeMember<CSSAnimationUpdate> m_animationUpdate;
 
     bool m_applyPropertyToRegularStyle;
     bool m_applyPropertyToVisitedLinkStyle;
 
     FontBuilder m_fontBuilder;
 
     OwnPtr<CachedUAStyle> m_cachedUAStyle;
 
     ElementStyleResources m_elementStyleResources;
 };
 
 } // namespace blink
 
 #endif // StyleResolverState_h