Use isSVG*Element() helpers more in SVG code (Part 4)

Source/core/svg/SVGTextPositioningElement.cpp

Index: Source/core/svg/SVGTextPositioningElement.cpp
diff --git a/Source/core/svg/SVGTextPositioningElement.cpp b/Source/core/svg/SVGTextPositioningElement.cpp
index ee6484632d50eb19a039fee7d39150ee2d4385f6..b73b7e1db4a1ca874615cd86abe01def638db535 100644
--- a/Source/core/svg/SVGTextPositioningElement.cpp
+++ b/Source/core/svg/SVGTextPositioningElement.cpp
@@ -129,14 +129,7 @@ SVGTextPositioningElement* SVGTextPositioningElement::elementFromRenderer(Render
     ASSERT(node);
     ASSERT(node->isSVGElement());
 
-    if (!node->hasTagName(SVGNames::textTag)
-#if ENABLE(SVG_FONTS)
-        && !node->hasTagName(SVGNames::altGlyphTag)
-#endif
-        && !node->hasTagName(SVGNames::tspanTag))
-        return 0;
-
-    return toSVGTextPositioningElement(node);
+    return isSVGTextPositioningElement(*node) ? toSVGTextPositioningElement(node) : 0;
 }
 
 }