Avoid transiently creating disallowed elements when building <use> trees

Source/core/svg/SVGUseElement.cpp

Index: Source/core/svg/SVGUseElement.cpp
diff --git a/Source/core/svg/SVGUseElement.cpp b/Source/core/svg/SVGUseElement.cpp
index 3ff826babec787ae574c67827c586484f61a4e86..502f6a464299c0762d5a4ebdb5c2d40b27435852 100644
--- a/Source/core/svg/SVGUseElement.cpp
+++ b/Source/core/svg/SVGUseElement.cpp
@@ -373,7 +373,7 @@ void SVGUseElement::buildShadowAndInstanceTree(SVGElement* target)
 
     // Do not allow self-referencing.
     // 'target' may be null, if it's a non SVG namespaced element.
-    if (!target || target == this)
+    if (!target || target == this || isDisallowedElement(target))
         return;
 
     // Set up root SVG element in shadow tree.