mPresShell = getter_AddRefs(NS_GetWeakReference(aPresShell));
DummyLayoutRequest::DummyLayoutRequest(){  NS_INIT_REFCNT();  if (gRefCnt++ == 0) {      nsresult rv;      rv = NS_NewURI(&gURI, "about:layout-dummy-request", nsnull);      NS_ASSERTION(NS_SUCCEEDED(rv), "unable to create about:layout-dummy-request");  }}