Add toSVGRootInlineBox(), and use it as much as we can

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 351 matching lines @@
     return ts;
 }
 
 static TextStream& operator<<(TextStream& ts, const RenderSVGRoot& root)
 {
     return writePositionAndStyle(ts, root);
 }
 
 static void writeRenderSVGTextBox(TextStream& ts, const RenderSVGText& text)
 {
-    SVGRootInlineBox* box = static_cast<SVGRootInlineBox*>(text.firstRootBox());
+    SVGRootInlineBox* box = toSVGRootInlineBox(text.firstRootBox());
     if (!box)
         return;
 
     ts << " " << enclosingIntRect(FloatRect(text.location(), FloatSize(box->logicalWidth(), box->logicalHeight())));
 
     // FIXME: Remove this hack, once the new text layout engine is completly landed. We want to preserve the old layout test results for now.
     ts << " contains 1 chunk(s)";
 
     if (text.parent() && (text.parent()->style()->visitedDependentColor(CSSPropertyColor) != text.style()->visitedDependentColor(CSSPropertyColor)))
         writeNameValuePair(ts, "color", text.resolveColor(CSSPropertyColor).nameForRenderTreeAsText());
@@ skipping 276 matching lines @@
             ts << " ";
             writeNameAndQuotedValue(ts, "filter", svgStyle->filterResource());
             ts << " ";
             writeStandardPrefix(ts, *filter, 0);
             ts << " " << filter->resourceBoundingBox(&renderer) << "\n";
         }
     }
 }
 
 } // namespace WebCore