Get rid of loops looking for the first Element ancestor

Source/core/xml/parser/XMLDocumentParser.cpp

Index: Source/core/xml/parser/XMLDocumentParser.cpp
diff --git a/Source/core/xml/parser/XMLDocumentParser.cpp b/Source/core/xml/parser/XMLDocumentParser.cpp
index 8ed8307aa3f33f9ab87f3c1c04a7d3fc444866af..7f0e69fd65e9e60ac1595b5732ab4bbccc4ff458 100644
--- a/Source/core/xml/parser/XMLDocumentParser.cpp
+++ b/Source/core/xml/parser/XMLDocumentParser.cpp
@@ -801,10 +801,10 @@ XMLDocumentParser::XMLDocumentParser(DocumentFragment* fragment, Element* parent
     while (parentElement) {
         elemStack.append(parentElement);
 
-        ContainerNode* n = parentElement->parentNode();
-        if (!n || !n->isElementNode())
+        Element* grandParentElement = parentElement->parentElement();
+        if (!grandParentElement)
             break;
-        parentElement = toElement(n);
+        parentElement = grandParentElement;
     }
 
     if (elemStack.isEmpty())