Intent to prototype: Scoped custom element registries

[Keith Cirkel]

Summary:

  Scoped custom element registries are a strongly desired feature from the Web Components community. They allow creating per-shadowroot registries. While there is no current spec, there are implementations in both WebKit and Chromium. I intend to spend the next couple of months prototyping an implementation in Gecko.

Bug:

  https://bugzilla.mozilla.org/show_bug.cgi?id=1874414.

Specification:

  https://github.com/WICG/webcomponents/blob/gh-pages/proposals/Scoped-Custom-Element-Registries.md

Standards Body:

  WICG

Platform coverage:

  all.

Preference:

  dom.scoped-custom-element-registries.enabled

DevTools bug:

 n/a.

Link to standards-positions discussion:

  https://github.com/mozilla/standards-positions/issues/424.

Other browsers:

  Blink: Prototyping.

  WebKit: Prototyping.

web-platform-tests:

  Many exist, but more will be written during the implementation.