Introduce toSVGInlineFlowBox() and use it

Source/core/rendering/svg/SVGInlineFlowBox.cpp

 /*
  * Copyright (C) 2006 Oliver Hunt <ojh16@student.canterbury.ac.nz>
  * Copyright (C) 2006 Apple Computer Inc.
  * Copyright (C) 2007 Nikolas Zimmermann <zimmermann@kde.org>
  * Copyright (C) Research In Motion Limited 2010. All rights reserved.
  *
  * This library is free software; you can redistribute it and/or
  * modify it under the terms of the GNU Library General Public
  * License as published by the Free Software Foundation; either
  * version 2 of the License, or (at your option) any later version.
@@ skipping 25 matching lines @@
 void SVGInlineFlowBox::paintSelectionBackground(PaintInfo& paintInfo)
 {
     ASSERT(paintInfo.phase == PaintPhaseForeground || paintInfo.phase == PaintPhaseSelection);
     ASSERT(!paintInfo.context->paintingDisabled());
 
     PaintInfo childPaintInfo(paintInfo);
     for (InlineBox* child = firstChild(); child; child = child->nextOnLine()) {
         if (child->isSVGInlineTextBox())
             toSVGInlineTextBox(child)->paintSelectionBackground(childPaintInfo);
         else if (child->isSVGInlineFlowBox())
-            static_cast<SVGInlineFlowBox*>(child)->paintSelectionBackground(childPaintInfo);
+            toSVGInlineFlowBox(child)->paintSelectionBackground(childPaintInfo);
     }
 }
 
 void SVGInlineFlowBox::paint(PaintInfo& paintInfo, const LayoutPoint&, LayoutUnit, LayoutUnit)
 {
     ASSERT(paintInfo.phase == PaintPhaseForeground || paintInfo.phase == PaintPhaseSelection);
     ASSERT(!paintInfo.context->paintingDisabled());
 
     RenderObject* boxRenderer = renderer();
     ASSERT(boxRenderer);
@@ skipping 76 matching lines @@
 
                 markerRect.unite(fragmentRect);
             }
         }
 
         toRenderedDocumentMarker(marker)->setRenderedRect(textRenderer->localToAbsoluteQuad(markerRect).enclosingBoundingBox());
     }
 }
 
 } // namespace WebCore