Bug 1598809 - Increase the timeout for browser_blockingSessionStorage.js even more

Differential Revision: https://phabricator.services.mozilla.com/D55041

--HG--
extra : moz-landing-system : lando

toolkit/components/antitracking/test/browser/browser_blockingSessionStorage.js

@@ -1,6 +1,6 @@
 /* import-globals-from antitracking_head.js */
 
-requestLongerTimeout(2);
+requestLongerTimeout(4);
 
 AntiTracking.runTestInNormalAndPrivateMode(
   "sessionStorage",