@viewport lengths relative to initial font.

Source/core/css/resolver/ViewportStyleResolver.cpp

 /*
  * Copyright (C) 2012 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 98 matching lines @@
     RefPtr<CSSValue> value = m_propertySet->getPropertyCSSValue(id);
     if (!value || !value->isPrimitiveValue())
         return defaultValue;
 
     CSSPrimitiveValue* primitiveValue = toCSSPrimitiveValue(value.get());
 
     if (primitiveValue->isNumber() || primitiveValue->isPx())
         return primitiveValue->getFloatValue();
 
     if (primitiveValue->isFontRelativeLength())
-        return primitiveValue->getFloatValue() * m_document->documentElement()->renderStyle()->fontDescription().computedSize();
+        return primitiveValue->getFloatValue() * m_document->renderStyle()->fontDescription().computedSize();
 
     if (primitiveValue->isPercentage()) {
         float percentValue = primitiveValue->getFloatValue() / 100.0f;
         switch (id) {
         case CSSPropertyMaxHeight:
         case CSSPropertyMinHeight:
             ASSERT(m_document->initialViewportSize().height() > 0);
             return percentValue * m_document->initialViewportSize().height();
         case CSSPropertyMaxWidth:
         case CSSPropertyMinWidth:
@@ skipping 19 matching lines @@
     case CSSValueZoom:
         return defaultValue;
     case CSSValueFixed:
         return 0;
     default:
         return defaultValue;
     }
 }
 
 } // namespace WebCore