Fix small, localized leak of HTTP atoms. Well tested on MacOS and under Purify with no ill effects. r=gagan

netwerk/protocol/http/src/nsHTTPResponse.cpp

@@ -368,7 +368,7 @@ nsresult nsHTTPResponse::ParseHeader(nsCString& aHeaderString)
     aHeaderString.Cut(0, colonOffset+1);
     aHeaderString.Trim(" ");
 
-    headerAtom = NS_NewAtom(headerKey.GetBuffer());
+    headerAtom = getter_AddRefs(NS_NewAtom(headerKey.GetBuffer()));
     if (headerAtom) {
         rv = ProcessHeader(headerAtom, aHeaderString);
     } else {