Use DEFINE_NODE_TYPE_CASTS instead of using manual toSVGFooElement()

Source/core/rendering/svg/SVGRenderTreeAsText.cpp

 /*
  * Copyright (C) 2004, 2005, 2007, 2009 Apple Inc. All rights reserved.
  *           (C) 2005 Rob Buis <buis@kde.org>
  *           (C) 2006 Alexander Kellett <lypanov@kde.org>
  * Copyright (C) Research In Motion Limited 2010. 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
@@ skipping 256 matching lines @@
     if (object.isSVGShape()) {
         const RenderSVGShape& shape = static_cast<const RenderSVGShape&>(object);
         ASSERT(shape.element());
 
         Color fallbackColor;
         if (RenderSVGResource* strokePaintingResource = RenderSVGResource::strokePaintingResource(const_cast<RenderSVGShape*>(&shape), shape.style(), fallbackColor)) {
             TextStreamSeparator s(" ");
             ts << " [stroke={" << s;
             writeSVGPaintingResource(ts, strokePaintingResource);
 
-            SVGLengthContext lengthContext(toSVGElement(shape.element()));
+            SVGLengthContext lengthContext(shape.element());
             double dashOffset = svgStyle->strokeDashOffset().value(lengthContext);
             double strokeWidth = svgStyle->strokeWidth().value(lengthContext);
             const Vector<SVGLength>& dashes = svgStyle->strokeDashArray();
 
             DashArray dashArray;
             const Vector<SVGLength>::const_iterator end = dashes.end();
             for (Vector<SVGLength>::const_iterator it = dashes.begin(); it != end; ++it)
                 dashArray.append((*it).value(lengthContext));
 
             writeIfNotDefault(ts, "opacity", svgStyle->strokeOpacity(), 1.0f);
@@ skipping 371 matching lines @@
             ts << " ";
             writeNameAndQuotedValue(ts, "filter", svgStyle->filterResource());
             ts << " ";
             writeStandardPrefix(ts, *filter, 0);
             ts << " " << filter->resourceBoundingBox(&renderer) << "\n";
         }
     }
 }
 
 } // namespace WebCore