Implements the algorithms that keep <selectedcontent> elements in sync with
the selected <option>: RunSelectednessSettingAlgorithm (replaces
CheckSelectSomething), ScheduleSelectedContentUpdate /
UpdateDescendantSelectedContentElements (microtask-based), per-element
CloneOptionIntoSelectedContent, and HTMLSelectedContentElement BindToTree
disabled computation per PR #12263.
Differential Revision: https://phabricator.services.mozilla.com/D290554
Implements the algorithms that keep <selectedcontent> elements in sync with
the selected <option>: RunSelectednessSettingAlgorithm (replaces
CheckSelectSomething), ScheduleSelectedContentUpdate /
UpdateDescendantSelectedContentElements (microtask-based), per-element
CloneOptionIntoSelectedContent, and HTMLSelectedContentElement BindToTree
disabled computation per PR #12263.
Differential Revision: https://phabricator.services.mozilla.com/D290554