Introduce toSVGLineElement(), 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 319 matching lines @@
     SVGElement* svgElement = toSVGElement(shape.node());
     SVGLengthContext lengthContext(svgElement);
 
     if (svgElement->hasTagName(SVGNames::rectTag)) {
         SVGRectElement* element = toSVGRectElement(svgElement);
         writeNameValuePair(ts, "x", element->xCurrentValue().value(lengthContext));
         writeNameValuePair(ts, "y", element->yCurrentValue().value(lengthContext));
         writeNameValuePair(ts, "width", element->widthCurrentValue().value(lengthContext));
         writeNameValuePair(ts, "height", element->heightCurrentValue().value(lengthContext));
     } else if (svgElement->hasTagName(SVGNames::lineTag)) {
-        SVGLineElement* element = static_cast<SVGLineElement*>(svgElement);
+        SVGLineElement* element = toSVGLineElement(svgElement);
         writeNameValuePair(ts, "x1", element->x1CurrentValue().value(lengthContext));
         writeNameValuePair(ts, "y1", element->y1CurrentValue().value(lengthContext));
         writeNameValuePair(ts, "x2", element->x2CurrentValue().value(lengthContext));
         writeNameValuePair(ts, "y2", element->y2CurrentValue().value(lengthContext));
     } else if (svgElement->hasTagName(SVGNames::ellipseTag)) {
         SVGEllipseElement* element = static_cast<SVGEllipseElement*>(svgElement);
         writeNameValuePair(ts, "cx", element->cxCurrentValue().value(lengthContext));
         writeNameValuePair(ts, "cy", element->cyCurrentValue().value(lengthContext));
         writeNameValuePair(ts, "rx", element->rxCurrentValue().value(lengthContext));
         writeNameValuePair(ts, "ry", element->ryCurrentValue().value(lengthContext));
@@ skipping 318 matching lines @@
             ts << " ";
             writeNameAndQuotedValue(ts, "filter", svgStyle->filterResource());
             ts << " ";
             writeStandardPrefix(ts, *filter, 0);
             ts << " " << filter->resourceBoundingBox(&renderer) << "\n";
         }
     }
 }
 
 } // namespace WebCore