SignInSheet refactored to use hooks

Reviewed By: passy

Differential Revision: D28788914

fbshipit-source-id: 5b000bff57d0fec7b8fafa4f5efd1c3e15caa766

desktop/app/src/chrome/fb-stubs/SignInSheet.tsx

@@ -7,12 +7,6 @@
  * @format
  */
 
-import {Component} from 'react';
+export default function SignInSheetFunc(_: {onHide: () => any}) {
-
+  return null;
-class SignInSheet extends Component<{onHide: () => any}, {}> {
-  render() {
-    return null;
-  }
 }
-
-export default SignInSheet;