if (!mPresShell)
if (!mPresShell) {
NS_IMETHODIMP nsEditorBoxObject::GetDocShell(nsIDocShell** aResult){  *aResult = nsnull;  if (!mPresShell)    return NS_OK;  nsCOMPtr<nsISupports> subShell;  mPresShell->GetSubShellFor(mContent, getter_AddRefs(subShell));  if(!subShell)    return NS_OK;  return CallQueryInterface(subShell, aResult); //Addref happens here.}