use-local-storage-state test

Branch: fix/localstorage-null-sentinel-value (Approach B)

0

isPersistent: true

How to test the bug:

Open Firefox, go to about:config, set dom.storage.enabled to false, then reload this page.

Expected: Counter shows 0 (defaultValue), isPersistent is false

Fixed: Counter shows 0 (defaultValue), isPersistent is true (value equals default). After changing, isPersistent becomes false.