* Change how CDN_HOST is passed down to make assets build reproducible
* Change webpacker/webpack configuration to dynamically load publicPath based on meta header
* Fix embedded layout missing the cdn-host meta header
app/javascript/mastodon/main.js delayed the execution of modules,
but other entry points didn't. That leads to failure in executing
modules, which requires those polyfills.
Strictly enforce the rule to require any modules after loading
polyfill in entry points.
ThibG