Add toSVGMissingGlyphElement(), and use it.

Source/core/svg/SVGFontElement.cpp

 /*
  * Copyright (C) 2007 Eric Seidel <eric@webkit.org>
  * 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 55 matching lines @@
         m_horizontalKerningPairs.clear();
         m_verticalKerningPairs.clear();
     }
     m_isGlyphCacheValid = false;
 }
 
 SVGMissingGlyphElement* SVGFontElement::firstMissingGlyphElement() const
 {
     for (Node* child = firstChild(); child; child = child->nextSibling()) {
         if (child->hasTagName(SVGNames::missing_glyphTag))
-            return static_cast<SVGMissingGlyphElement*>(child);
+            return toSVGMissingGlyphElement(child);
     }
 
     return 0;
 }
 
 void SVGFontElement::registerLigaturesInGlyphCache(Vector<String>& ligatures)
 {
     ASSERT(!ligatures.isEmpty());
 
     // Register each character of a ligature in the map, if not present.
@@ skipping 47 matching lines @@
 
             // Register ligatures, if needed, don't mix up with surrogate pairs though!
             if (unicode.length() > 1 && !U16_IS_SURROGATE(unicode[0]))
                 ligatures.append(unicode.string());
         } else if (child->hasTagName(SVGNames::hkernTag)) {
             SVGHKernElement* hkern = static_cast<SVGHKernElement*>(child);
             hkern->buildHorizontalKerningPair(m_horizontalKerningPairs);
         } else if (child->hasTagName(SVGNames::vkernTag)) {
             SVGVKernElement* vkern = static_cast<SVGVKernElement*>(child);
             vkern->buildVerticalKerningPair(m_verticalKerningPairs);
-        } else if (child->hasTagName(SVGNames::missing_glyphTag) && !firstMissingGlyphElement)
-            firstMissingGlyphElement = static_cast<SVGMissingGlyphElement*>(child);
+        } else if (child->hasTagName(SVGNames::missing_glyphTag) && !firstMissingGlyphElement) {
+            firstMissingGlyphElement = toSVGMissingGlyphElement(child);
+        }
     }
 
     // Register each character of each ligature, if needed.
     if (!ligatures.isEmpty())
         registerLigaturesInGlyphCache(ligatures);
 
     // Register missing-glyph element, if present.
     if (firstMissingGlyphElement) {
         SVGGlyph svgGlyph = SVGGlyphElement::buildGenericGlyphIdentifier(firstMissingGlyphElement);
         m_glyphMap.appendToGlyphTable(svgGlyph);
@@ skipping 97 matching lines @@
 
 Glyph SVGFontElement::missingGlyph()
 {
     ensureGlyphCache();
     return m_missingGlyph;
 }
 
 }
 
 #endif // ENABLE(SVG_FONTS)