Change I51cfd5637 adds the ability to opt-in to testing mw.loader.store by manually setting a cookie. This is not a feature that we want to retain after the test phase concludes. When mw.loader.store is adequately tested, the relevant lines of code should be removed from mediawiki.js. This should happen long before the 1.23 release.
Version: 1.23.0
Severity: blocker
URL: https://meta.wikimedia.org/wiki/Research:Module_storage_performance