core(pwa): remove works-offline and offline-start-url audits

[paulirish]

Writing and maintaining these audits (well, the gatherers) was ... exciting. Over the past 4 years, I believe we changed our strategy for offline-start-url a good 5 times. 🤣

But now that we rely on the installabilityErrors from the protocol (#8223 #10515), we don't need to have custom functional tests.

And now that load-fast-enough-for-pwa has been removed (#11764), there is no longer a "Fast and reliable" group within PWA. (This PR complements #11745 which revamps installable-manifest and #11798 which makes service-worker hidden)

This PR removes the audits, gatherers, icon & gauge handling, and remaining references.

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Look of the new PWA section with the 3 states:

[brendankenny]

😍

[brendankenny]

?

[paulirish]

heh. i didn't love how the PWA logo looked in darkmode so i experimented with changes.. ultimately they weren't good enough to keep. thx for the catch.

[brendankenny]

But now that we rely on the installabilityErrors from the protocol (#8223 #10515), we don't need to have custom functional tests.

Not equivalent checks, of course :) start-url has been a problem, but works-offline won't have an equivalent for a while.

What are you thinking of for a timeline? With #11745 we'll have just the fetch handler check. In Chrome 93 (in August) an offline check becomes part of the installability requirements so we'll have one again. Turn on warn-not-offline-capable as a warning sometime in between now and August (like when it reaches stable)? Use the warning as a requirement in LH v8 so the big PWA change is aligned with our major release? Or just match Chrome installability and be ok with changes?

[paulirish]

But now that we rely on the installabilityErrors from the protocol (#8223 #10515), we don't need to have custom functional tests.

Not equivalent checks, of course :) start-url has been a problem, but works-offline won't have an equivalent for a while.

yes. truth.

What are you thinking of for a timeline?

basic plan is shipping this in LH 7, yeah. :)

With #11745 we'll have just the fetch handler check. In Chrome 93 (in August) an offline check becomes part of the installability requirements so we'll have one again.

warn-not-offline-capable is now on by default in chrome 89 (current canary): https://chromium-review.googlesource.com/c/chromium/src/+/2580668 (thus our CI breakages last week)

so all canary folk have the functional offline check and it reports through to us. 👍

oh and if you didn't spot it.. #11745 now adds an audit warning when warn-not-offline-capable is present.

anyone using this lighthouse with chrome stable will yeah have a little gap as nothing is doing a functional offline test (LH or crbug.com/965802). (fwiw, m89 ships to stable ~march 2nd) But I don't see that as a serious problem. It would also be a problem for folks writing their own service worker and where Lighthouse would be surfacing a problem they wouldn't find themselves.

Or just match Chrome installability and be ok with changes?

Thats exactly where my priorities are yeah.

[brendankenny]

LGTM!

cc @connorjclark if you still want to take a look