Add toRenderSVGResourceMarker() fuction, and use it.

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 493 matching lines @@
         RefPtr<SVGFilter> dummyFilter = SVGFilter::create(AffineTransform(), dummyRect, dummyRect, dummyRect, true);
         if (RefPtr<SVGFilterBuilder> builder = filter->buildPrimitives(dummyFilter.get())) {
             if (FilterEffect* lastEffect = builder->lastEffect())
                 lastEffect->externalRepresentation(ts, indent + 1);
         }
     } else if (resource->resourceType() == ClipperResourceType) {
         RenderSVGResourceClipper* clipper = static_cast<RenderSVGResourceClipper*>(resource);
         writeNameValuePair(ts, "clipPathUnits", clipper->clipPathUnits());
         ts << "\n";
     } else if (resource->resourceType() == MarkerResourceType) {
-        RenderSVGResourceMarker* marker = static_cast<RenderSVGResourceMarker*>(resource);
+        RenderSVGResourceMarker* marker = toRenderSVGResourceMarker(resource);
         writeNameValuePair(ts, "markerUnits", marker->markerUnits());
         ts << " [ref at " << marker->referencePoint() << "]";
         ts << " [angle=";
         if (marker->angle() == -1)
             ts << "auto" << "]\n";
         else
             ts << marker->angle() << "]\n";
     } else if (resource->resourceType() == PatternResourceType) {
         RenderSVGResourcePattern* pattern = static_cast<RenderSVGResourcePattern*>(resource);
 
@@ skipping 138 matching lines @@
             ts << " ";
             writeNameAndQuotedValue(ts, "filter", svgStyle->filterResource());
             ts << " ";
             writeStandardPrefix(ts, *filter, 0);
             ts << " " << filter->resourceBoundingBox(&renderer) << "\n";
         }
     }
 }
 
 } // namespace WebCore