[wpt] upgrade webstorage tests to non-tentative
These are supported cross vendor:
https://wpt.fyi/results/webstorage?label=experimental&label=master&aligned&q=tentative
Bug: 3534256
Change-Id: I25f713445724248f76a0888bcd0b62df0f19bd6b
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/5713510
Reviewed-by: Steven Bingler bingler@chromium.org
Reviewed-by: Vladimir Levin vmpstr@chromium.org
Auto-Submit: Ari Chivukula arichiv@chromium.org
Commit-Queue: Ari Chivukula arichiv@chromium.org
Cr-Commit-Position: refs/heads/main@{#1328303}