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

Source/core/svg/SVGFontFaceFormatElement.cpp

Index: Source/core/svg/SVGFontFaceFormatElement.cpp
diff --git a/Source/core/svg/SVGFontFaceFormatElement.cpp b/Source/core/svg/SVGFontFaceFormatElement.cpp
index 5468bdb240e49de02a0d0803db8c326453c8d15d..5aaef55580a589e9121e7bb4d728afbd1c7fedd7 100644
--- a/Source/core/svg/SVGFontFaceFormatElement.cpp
+++ b/Source/core/svg/SVGFontFaceFormatElement.cpp
@@ -44,15 +44,15 @@ void SVGFontFaceFormatElement::childrenChanged(bool changedByParser, Node* befor
 {
     SVGElement::childrenChanged(changedByParser, beforeChange, afterChange, childCountDelta);
 
-    if (!parentNode() || !parentNode()->hasTagName(font_face_uriTag))
+    if (!isSVGFontFaceUriElement(parentNode()))
         return;
 
     ContainerNode* ancestor = parentNode()->parentNode();
-    if (!ancestor || !ancestor->hasTagName(font_face_srcTag))
+    if (!isSVGFontFaceSrcElement(ancestor))
         return;
 
     ancestor = ancestor->parentNode();
-    if (ancestor && ancestor->hasTagName(font_faceTag))
+    if (isSVGFontFaceElement(ancestor))
         toSVGFontFaceElement(ancestor)->rebuildFontFace();
 }