Consistently use ElementTraversal API when looking for an Element

Source/core/rendering/svg/RenderSVGResourcePattern.cpp

 /*
  * Copyright (C) 2006 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.
  *
  * This library is distributed in the hope that it will be useful,
@@ skipping 248 matching lines @@
 
     // Apply tile image transformations.
     if (!tileImageTransform.isIdentity())
         tileImageContext->concatCTM(tileImageTransform);
 
     AffineTransform contentTransformation;
     if (attributes.patternContentUnits() == SVGUnitTypes::SVG_UNIT_TYPE_OBJECTBOUNDINGBOX)
         contentTransformation = tileImageTransform;
 
     // Draw the content into the ImageBuffer.
-    for (Node* node = attributes.patternContentElement()->firstChild(); node; node = node->nextSibling()) {
-        if (!node->isSVGElement() || !node->renderer())
+    for (Element* element = ElementTraversal::firstWithin(*attributes.patternContentElement()); element; element = ElementTraversal::nextSibling(*element)) {
+        if (!element->isSVGElement() || !element->renderer())
             continue;
-        if (node->renderer()->needsLayout())
+        if (element->renderer()->needsLayout())
             return nullptr;
-        SVGRenderingContext::renderSubtree(tileImage->context(), node->renderer(), contentTransformation);
+        SVGRenderingContext::renderSubtree(tileImage->context(), element->renderer(), contentTransformation);
     }
 
     return tileImage.release();
 }
 
 }