eslint + flowtype fixes

src/components/Notification/components/NotificationButton/index.js

@@ -1,7 +1,7 @@
 /* @flow */
 
 import * as React from 'react';
-import styled, { css } from 'styled-components';
+import styled from 'styled-components';
 import PropTypes from 'prop-types';
 import Icon from 'components/Icon';
 import colors from 'config/colors';
@@ -17,6 +17,7 @@ type Props = {
         size: number;
     };
     onClick: () => void;
+    isLoading?: boolean;
     children: React.Node;
 };