"Web components" page missing Baseline status

What information was incorrect, unhelpful, or incomplete?

https://developer.mozilla.org/en-US/docs/Web/API/Web_components

What did you expect to see?

There should be a green "Baseline: Widely Available" banner on this page.

Do you have any supporting links, references, or citations?

https://github.com/mdn/rari/pull/554 which fixed https://github.com/mdn/fred/issues/1321

Do you have anything more you want to share?

This page lists two browser-compat keys:

browser-compat:
  - html.elements.template
  - api.ShadowRoot

Apropos https://github.com/mdn/fred/issues/1321#issuecomment-4022887765

yes, we've never handled multiple bcd keys for baseline banners: the logic gets surprisingly tricky.

In this case, though, we should probably just detect that the two keys are the same feature and show that banner: I've opened mdn/rari#554 which does that.

We should go a bit further and show a baseline banner when all of the page's web features have baseline status "high". (This would result in the banner disappearing if just one of the features has a baseline reversion, but reversions from "high" are extremely rare.)

Start with the Web Components page and its two browser-compat keys, then review the behavior described in mdn/rari#554 and the discussion in mdn/fred#1321. Done means the page displays the green Baseline banner when the listed web features share high Baseline status, while accounting for a possible reversion.