mDocument = aDocument; mURL = aURL; NS_ADDREF(mURL);
HTMLStyleSheetImpl::Init(nsIURI* aURL, nsIDocument* aDocument){  NS_PRECONDITION(aURL && aDocument, "null ptr");  if (! aURL || ! aDocument)    return NS_ERROR_NULL_POINTER;  if (mURL || mDocument)    return NS_ERROR_ALREADY_INITIALIZED;  mDocument = aDocument; // not refcounted!  mURL = aURL;  NS_ADDREF(mURL);  return NS_OK;}