Use isSVG*Element() helpers more in SVG code (Part 1)

Source/core/svg/SVGFontData.cpp

 /*
  * Copyright (C) 2008 Nikolas Zimmermann <zimmermann@kde.org>
  *
  * 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.
  *
  * This library is distributed in the hope that it will be useful,
  * but WITHOUT ANY WARRANTY; without even the implied warranty of
@@ skipping 158 matching lines @@
     Vector<AtomicString> altGlyphNames;
 
     if (renderObject) {
         RenderObject* parentRenderObject = renderObject->isText() ? renderObject->parent() : renderObject;
         ASSERT(parentRenderObject);
 
         isVerticalText = parentRenderObject->style()->svgStyle()->isVerticalWritingMode();
         if (Element* parentRenderObjectElement = toElement(parentRenderObject->node())) {
             language = parentRenderObjectElement->getAttribute(XMLNames::langAttr);
 
-            if (parentRenderObjectElement->hasTagName(SVGNames::altGlyphTag)) {
-                if (!toSVGAltGlyphElement(parentRenderObjectElement)->hasValidGlyphElements(altGlyphNames))
+            if (isSVGAltGlyphElement(*parentRenderObjectElement)) {
+                if (!toSVGAltGlyphElement(*parentRenderObjectElement).hasValidGlyphElements(altGlyphNames))
                     altGlyphNames.clear();
             }
         }
     }
 
     Vector<SVGGlyph> glyphs;
     size_t altGlyphNamesSize = altGlyphNames.size();
     if (altGlyphNamesSize) {
         for (size_t index = 0; index < altGlyphNamesSize; ++index)
             associatedFontElement->collectGlyphsForAltGlyphReference(altGlyphNames[index], glyphs);
@@ skipping 119 matching lines @@
             mirroredCharacters.append(mirroredChar(character));
         }
     }
 
     return mirroredCharacters.toString();
 }
 
 } // namespace WebCore
 
 #endif