Mounts the card from `dist/` the way Home Assistant does, by URL with a
HACS tag, and asserts the entry stays a facade, that no chunk imports
it, that the browser is served the file unmodified, and that the card
starts up and fetches a language chunk lazily.
Runs in Chromium, Firefox and WebKit, so a change of bundler or minifier
is checked against every engine.
Dermot Duffy