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

Source/core/svg/SVGAltGlyphItemElement.cpp

 /*
  * Copyright (C) 2011 Leo Yang <leoyang@webkit.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
  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  * Library General Public License for more details.
  *
  * You should have received a copy of the GNU Library General Public License
  * along with this library; see the file COPYING.LIB.  If not, write to
  * the Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor,
  * Boston, MA 02110-1301, USA.
  */
 
 #include "config.h"
 
 #if ENABLE(SVG_FONTS)
 #include "core/svg/SVGAltGlyphItemElement.h"
 
+#include "core/dom/ElementTraversal.h"
 #include "core/svg/SVGGlyphRefElement.h"
 
 namespace WebCore {
 
 inline SVGAltGlyphItemElement::SVGAltGlyphItemElement(Document& document)
     : SVGElement(SVGNames::altGlyphItemTag, document)
 {
     ScriptWrappable::init(this);
 }
 
 PassRefPtr<SVGAltGlyphItemElement> SVGAltGlyphItemElement::create(Document& document)
 {
     return adoptRef(new SVGAltGlyphItemElement(document));
 }
 
 bool SVGAltGlyphItemElement::hasValidGlyphElements(Vector<AtomicString>& glyphNames) const
 {
     // Spec: http://www.w3.org/TR/SVG/text.html#AltGlyphItemElement
     // The ‘altGlyphItem’ element defines a candidate set of possible glyph substitutions.
     // The first ‘altGlyphItem’ element whose referenced glyphs are all available is chosen.
     // Its glyphs are rendered instead of the character(s) that are inside of the referencing
     // ‘altGlyph’ element.
     //
     // Here we fill glyphNames and return true only if all referenced glyphs are valid and
     // there is at least one glyph.
-    for (Node* child = firstChild(); child; child = child->nextSibling()) {
-        if (child->hasTagName(SVGNames::glyphRefTag)) {
-            AtomicString referredGlyphName;
-            if (toSVGGlyphRefElement(child)->hasValidGlyphElement(referredGlyphName))
-                glyphNames.append(referredGlyphName);
-            else {
-                glyphNames.clear();
-                return false;
-            }
+    for (SVGGlyphRefElement* glyph = Traversal<SVGGlyphRefElement>::firstChild(*this); glyph; glyph = Traversal<SVGGlyphRefElement>::nextSibling(*glyph)) {
+        AtomicString referredGlyphName;
+        if (glyph->hasValidGlyphElement(referredGlyphName)) {
+            glyphNames.append(referredGlyphName);
+        } else {
+            glyphNames.clear();
+            return false;
         }
     }
     return !glyphNames.isEmpty();
 }
 
 }
 
 #endif