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

Source/core/svg/SVGFontFaceUriElement.cpp

 /*
  * Copyright (C) 2007 Eric Seidel <eric@webkit.org>
  * Copyright (C) 2009 Apple Inc. 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 57 matching lines @@
 }
 
 void SVGFontFaceUriElement::childrenChanged(bool changedByParser, Node* beforeChange, Node* afterChange, int childCountDelta)
 {
     SVGElement::childrenChanged(changedByParser, beforeChange, afterChange, childCountDelta);
 
     if (!parentNode() || !parentNode()->hasTagName(font_face_srcTag))
         return;
 
     ContainerNode* grandparent = parentNode()->parentNode();
-    if (grandparent && grandparent->hasTagName(font_faceTag))
-        toSVGFontFaceElement(grandparent)->rebuildFontFace();
+    if (isSVGFontFaceElement(grandparent))
+        toSVGFontFaceElement(*grandparent).rebuildFontFace();
 }
 
 Node::InsertionNotificationRequest SVGFontFaceUriElement::insertedInto(ContainerNode* rootParent)
 {
     loadFont();
     return SVGElement::insertedInto(rootParent);
 }
 
 void SVGFontFaceUriElement::loadFont()
 {
@@ skipping 10 matching lines @@
             m_resource->beginLoadIfNeeded(fetcher);
         }
     } else {
         m_resource = 0;
     }
 }
 
 }
 
 #endif // ENABLE(SVG_FONTS)