SVG: Move/rename reference management to SVGElement

Source/core/svg/SVGPathElement.cpp

Index: Source/core/svg/SVGPathElement.cpp
diff --git a/Source/core/svg/SVGPathElement.cpp b/Source/core/svg/SVGPathElement.cpp
index c7478ef6419d67f870a2ad9dc4b764c3bd880d9d..eb753954655d01a376dca0359ccd34197bff8824 100644
--- a/Source/core/svg/SVGPathElement.cpp
+++ b/Source/core/svg/SVGPathElement.cpp
@@ -236,7 +236,7 @@ void SVGPathElement::invalidateMPathDependencies()
 {
     // <mpath> can only reference <path> but this dependency is not handled in
     // markForLayoutAndParentResourceInvalidation so we update any mpath dependencies manually.
-    if (SVGElementSet* dependencies = document().accessSVGExtensions().setOfElementsReferencingTarget(this)) {
+    if (SVGElementSet* dependencies = setOfIncomingReferences()) {
         SVGElementSet::iterator end = dependencies->end();
         for (SVGElementSet::iterator it = dependencies->begin(); it != end; ++it) {
             if (isSVGMPathElement(**it))