Name already in use

Tests: xhr/formdata/constructor-submitter.html.

Closes #8785.

Tests: https://wpt.fyi/results/html/semantics/popovers.

Additional context: https://open-ui.org/components/popup.research.explainer.

Prior PR: #8221. Closes #7785.

Fixes #8610.

* Split it into two variants: one which runs synchronously on HTML element removal, and one which runs during "update the rendering". Closes #8225.

* After this split, only the "update the rendering" variant causes the normal focus algorithms to run, and thus blur and change events to fire.

* Delete the confusing "somehow unfocused without another element being explicitly focused" sentence.

Fixes #3847. Fixes #6729.

In particular, fixes #4325, which documents a case where <link rel="stylesheet"> would increment, and never decrement, the script-blocking style sheet counter.

To do this without increasing the amount of action-at-a-distance in the spec, we move from a script-blocking style sheet counter to a script-blocking style sheet set. That also matches implementations better, and sets us up for fixing other issues in this area.

This implements the changes proposed here:
https://github.com/whatwg/html/wiki/dialog--initial-focus,-a-proposal#dialog-draft-text

Specifically:

1. Make the dialog focusing steps look at sequentially focusable elements instead of any focusable element.

2. Make the dialog element itself get focus if it has the autofocus="" attribute set.

3. Make the dialog element itself get focus as a fallback instead of focus being reset to the body element.

Closes #1929. Closes #2197. Closes #4184. Additional dialog issues remain open at https://github.com/whatwg/html/labels/topic%3A%20dialog.

For whatwg/xhr#366.

Fixes #8725. It has been broken since 0a97a81.

Follows w3c/webappsec-permissions-policy#505.

As discussed in #8743. Needed by WebGPU and WebCodecs.

This adds "has `Link` processing" to the link types table, which currently only has "Yes" values for preload and preconnect.

Closes #4224, and removes the reference to it in the spec. That issue was about the general lack of specification for the Link header, which has been resolved. #8741 tracks potentially adding Link header support for rel=stylesheet, but there's no need to retain notices in the spec about the possibility of this nonstandard feature. (The note was also quite incomplete, as it didn't talk about things like the cascade, document.styleSheets, etc.)

Also:

* Correct a few instances in the spec where "nested navigable"/"content navigable" was used, but "child navigable" was more correct, including in the names of the create and destroy algorithms.

* Export "navigable container" and "content navigable" (the latter scoped to "navigable container").

Closes #8713.

Using the filtered response's header list in case of a redirect meant we wouldn't get access to the COOP header.

#8740 tracks the more general issue here.

Prefetch is simply a fetch, which populates the HTTP cache, with no post-processing of the resource and with a special header Sec-Purpose: prefetch. (The latter is specified in whatwg/fetch#1576.)

Closes #5229.
Closes w3c/resource-hints#86.
Closes w3c/resource-hints#74.
Closes whatwg/fetch#1008.

Since https://drafts.csswg.org/ is often broken, it's better to use the https://w3c.github.io/csswg-drafts/ alternative. (See w3c/csswg-drafts#6528.) This replaces at least the links in the References section.

Infra handles that as per whatwg/infra#520.

This reverts commit a7f99da. See #8221 (comment) for context.

Although the variable is called initiatorOrigin at the call site, inside the "evaluate a javascript: URL" algorithm the parameter is actually named newDocumentOrigin, so that's the name that the algorithm should use.

Noticed in https://github.com/whatwg/html/pull/8447/files#r1067234151.

Closes #8251.

This update to the conformance requirements was missed in 448f240. Closes #8550.

Closes #7517.

Follows tc39/ecma262#2905. See https://docs.google.com/presentation/d/1RVUE-MENQT8dj2wxvMLMDxg_VoMOwiwNQQged39QIEU/edit for an overview of the changes here.

This is not a normative change, and in fact hosts can continue to have the same capabilities as before. But now, much of the graph-crawling work can be offloaded to the JavaScript specification.

Fixes #8053.

Closes #8619.

They have been useless for many years now.