1. htmlbuttonelement api: popovertargetaction

  2. htmlbuttonelement api: popovertargetelement

  3. htmlelement api: hidepopover

  4. htmlelement api: popover

  5. htmlelement api: showpopover

  6. htmlelement api: togglepopover

  7. htmlelement api: togglepopover: returns `true` or `false`

  8. htmlinputelement api: popovertargetaction

  9. htmlinputelement api: popovertargetelement

  10. css selector: `::backdrop`: support on popovers

  11. css selector: `:popover-open`

  12. html attribute: popover

  13. html attribute: popovertarget

  14. html attribute: popovertargetaction