Bug 1249685 - Use more nsCOMPtrs for stack variables in DOM code. r=smaug

dom/html/HTMLSelectElement.cpp

@@ -577,7 +577,7 @@ HTMLSelectElement::Add(nsGenericHTMLElement& aElement,
 
   // Just in case we're not the parent, get the parent of the reference
   // element
-  nsINode* parent = aBefore->Element::GetParentNode();
+  nsCOMPtr<nsINode> parent = aBefore->Element::GetParentNode();
   if (!parent || !nsContentUtils::ContentIsDescendantOf(parent, this)) {
     // NOT_FOUND_ERR: Raised if before is not a descendant of the SELECT
     // element.