add popover attributes/properties/methods/events

[keithamus]

Description

This adds the preliminary content for popover - it adds:

• the popover property to the HTMLElement properties list
• the showPopover, hidePopover, togglePopover methods to the HTMLElement methods list
• the toggle, beforetoggle events in the HTMLElement events list

Motivation

This will help as the foundations of documenting these features. I'm happy to continue this PR or make stacked PRs.

Additional details

Related issues and pull requests

#25125

[github-actions]

Preview URLs

• /en-US/docs/Web/API/HTMLElement
• /en-US/docs/Web/HTML/Global_attributes

Flaws (20)

URL: /en-US/docs/Web/HTML/Global_attributes
Title: Global attributes
Flaw count: 3

• broken_links:
  • Can't resolve /en-US/docs/Web/HTML/Global_attributes/popover
  • Can't resolve /en-US/docs/Web/HTML/button#popovertarget
  • Can't resolve /en-US/docs/Web/API/HTMLElement/showPopover/

---

URL: /en-US/docs/Web/API/HTMLElement
Title: HTMLElement
Flaw count: 17

• macros:
  • /en-US/docs/Web/API/HTMLElement/attributeStyleMap does not exist
  • /en-US/docs/Web/API/HTMLElement/draggable does not exist
  • /en-US/docs/Web/API/HTMLElement/popover does not exist
  • /en-US/docs/Web/API/HTMLElement/noModule does not exist
  • /en-US/docs/Web/API/HTMLElement/properties does not exist
  • and 11 more flaws omitted
• broken_links:
  • Can't resolve /en-US/docs/Web/HTML/Global_attributes/popover

[sideshowbarker]

Keith, thanks much, and congrats on landing your first docs change here — welcome aboard 🎉