Fix tabs offset

Summary: Tabs have a weird negative offsite in the mobile config section (they have everywhere by default, to escape their containers in a mac-style but it does hide them in this specific case)

Reviewed By: priteshrnandgaonkar

Differential Revision: D18448191

fbshipit-source-id: 792daa5a3ef1aa91df730bd185124076471e42d3

src/ui/components/Tabs.tsx

@@ -155,8 +155,14 @@ export default function Tabs(props: {
    * Elements to insert after all tabs in the tab list.
    */
   after?: Array<React.ReactNode>;
+  /**
+   * By default tabs are rendered in mac-style tabs, with a negative offset.
+   * By setting classic mode the classic style is rendered.
+   */
+  classic?: boolean;
 }) {
-  const tabsContainer = useContext(TabsContext);
+  const tabsContainer =
+    props.classic === true ? false : useContext(TabsContext);
 
   const {onActive} = props;
   const active: string | undefined =