I'd like to request an official position of WebKit on changing the default 'display' property value of <summary> to 'list-item', and the relevant changes below:

 - Add 'disclosure-closed' and 'disclosure-open' keywords to 'list-style-type' property

 - Add ::marker pseudo element selector support to <summary>

 - Remove ::-webkit-details-marker pseudo element selector

   [1] is the usage counter for ::-webkit-details-marker, and it shows the ratio of pages with elements matched to ::-webkit-details-marker in author stylesheets.  Currently the ratio is 0.0%.

Firefox already shipped all of them.

Specification: https://html.spec.whatwg.org/C/#the-details-and-summary-elements

Specification: https://drafts.csswg.org/css-counter-styles-3/#disclosure-open

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