Decouple font unit conversion in computeLengthDouble from RenderStyle.

Source/core/css/resolver/StyleResolverState.h

Index: Source/core/css/resolver/StyleResolverState.h
diff --git a/Source/core/css/resolver/StyleResolverState.h b/Source/core/css/resolver/StyleResolverState.h
index 5665c86c15c2331ba4f5a0ef10dc2e241c9e2465..c7ed24ff6977888fbf7a4c90b587b0c580936e76 100644
--- a/Source/core/css/resolver/StyleResolverState.h
+++ b/Source/core/css/resolver/StyleResolverState.h
@@ -62,8 +62,9 @@ public:
 
     void setStyle(PassRefPtr<RenderStyle> style)
     {
+        // FIXME: Improve RAII of StyleResolverState to remove this function.
         m_style = style;
-        m_cssToLengthConversionData.setStyle(m_style.get());
+        m_cssToLengthConversionData = CSSToLengthConversionData(m_style.get(), rootElementStyle(), document().renderView(), m_style->effectiveZoom());
         m_fontBuilder.setStyle(m_style.get());
     }
     const RenderStyle* style() const { return m_style.get(); }
@@ -72,6 +73,9 @@ public:
 
     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); }
+
     void setAnimationUpdate(PassOwnPtrWillBeRawPtr<CSSAnimationUpdate>);
     const CSSAnimationUpdate* animationUpdate() { return m_animationUpdate.get(); }
     PassOwnPtrWillBeRawPtr<CSSAnimationUpdate> takeAnimationUpdate();