add capital ref

Allow top layer elements to be nested within popovers

This allows top layer elements, including the dialog element, to be nested inside of an open popover, by not closing the popover when the new top layer element is opened. Without this patch, opening a modal dialog inside of a popover will make the page inert and make the dialog invisible.

Fixes #9998. See also whatwg/fullscreen#237.

Editorial: order of comparisons

For consistency:
- greater than or equal to
- less than or equal to

Improve element reflection

This attempts to make the following improvements:

1. Make it more clear that initializing attr is not the first step in an algorithm, but rather something that counts for all the list items.
2. Rewrite the associated element(s) fields as algorithms. As there are no downstream references so far this is a change we can still make.
3. Add another layer of caching that is separate from the FrozenArray to avoid having to compare a list of elements with a FrozenArray directly.

This helps with #10219.

Disable PageSwapEvent's activation on cross-origin redirects

Closes #10196.

Upstream Long Animation Frames monkey-patches

Long Animation Frames (https://w3c.github.io/long-animation-frames/) expects a few calls from HTML and other specs, for reporting when tasks, rendering or JS entry points take place. This moves those calls from the Long Animation Frames spec to HTML.

Preload: only allow certain values for as=""

Closes #8332.

Call the view transition page visibility change steps

This allows the CSS view-transitions spec to react to page visibility changes. Specifically, skip the active transition once a page is hidden.

See w3c/csswg-drafts#9543.

Style marquee using overflow: hidden

This matches Chromium and WebKit. Tests will be worked on in https://bugzilla.mozilla.org/show_bug.cgi?id=306344.

Editorial: export Element's innerText getter and setter steps

These will be used by Trusted Types (and eventually HTML once upstreamed) as part of shadowing this attribute to HTMLScriptElement.

Add getHTML() and serializable shadow roots

Corresponding DOM PR: whatwg/dom#1256.

Closes #8867.

Co-authored-by: Domenic Denicola <d@domenic.me>

Make buttons respect display: none/contents in button layout

Fixes #10238. This matches what is already implemented in browsers.

Remove duplicate requirement for 'overflow' for marquee

The duplication was introduced by #10243.

Meta: make all the SVGs darkmode-aware

Also tag them as such, so that they don't get a white background after whatwg/whatwg.org#439 is merged.

Warn that the XML syntax is not recommended

Closes #10237.

source

@@ -2668,7 +2668,6 @@ a.setAttribute('href', 'https://example.com/'); // change the content attribute
        <li><dfn data-x="concept-request-render-blocking" data-x-href="https://fetch.spec.whatwg.org/#request-render-blocking">render-blocking</dfn></li>
        <li><dfn data-x="concept-request-initiator-type" data-x-href="https://fetch.spec.whatwg.org/#request-initiator-type">initiator type</dfn></li>
        <li><dfn data-x-href="https://fetch.spec.whatwg.org/#concept-request-add-range-header">add a range header</dfn></li>
-       <li><dfn data-x="concept-response-method" data-x-href="https://fetch.spec.whatwg.org/#concept-method">method</dfn></li>
       </ul>
      </li>
      <li>