Decouple font unit conversion in computeLengthDouble from RenderStyle.

Source/core/css/resolver/ViewportStyleResolver.cpp

 /*
  * Copyright (C) 2012-2013 Intel Corporation. All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions
  * are met:
  *
  * 1. Redistributions of source code must retain the above
  *    copyright notice, this list of conditions and the following
  *    disclaimer.
@@ skipping 171 matching lines @@
     RenderStyle* documentStyle = m_document->renderStyle();
 
     // If we have viewport units the conversion will mark the document style as having viewport units.
     bool documentStyleHasViewportUnits = documentStyle->hasViewportUnits();
     documentStyle->setHasViewportUnits(false);
 
     FrameView* view = m_document->view();
     float width = view ? view->width() : 0;
     float height = view ? view->height() : 0;
 
-    Length result = primitiveValue->convertToLength<AnyConversion>(CSSToLengthConversionData(documentStyle, documentStyle, width, height, 1.0f));
+    CSSToLengthConversionData::FontSizes fontSizes(documentStyle, documentStyle);
+    CSSToLengthConversionData::ViewportSize viewportSize(width, height);
+    Length result = primitiveValue->convertToLength<AnyConversion>(CSSToLengthConversionData(documentStyle, fontSizes, viewportSize, 1.0f));
     if (documentStyle->hasViewportUnits())
         m_document->setHasViewportUnits();
     documentStyle->setHasViewportUnits(documentStyleHasViewportUnits);
 
     return result;
 }
 
 void ViewportStyleResolver::trace(Visitor* visitor)
 {
     visitor->trace(m_propertySet);
     visitor->trace(m_document);
 }
 
 } // namespace blink