⏫ Forwardport of #11219 to 2.3-develop branch

Applied pull request patch https://github.com/magento/magento2/pull/11219.patch (created by @mszydlo) based on commit(s):
  1. c1c5796

app/code/Magento/Theme/view/frontend/templates/js/polyfill.phtml

@@ -126,7 +126,7 @@
             };
 
             window.localStorage.__proto__ = window.localStorage = new Storage('local');
-            window.sessionStorage.__proto__ = window.sessionStorag = new Storage('session');
+            window.sessionStorage.__proto__ = window.sessionStorage = new Storage('session');
         })();
     }
 </script>