/**
 * Popover API & HTMLDialogElement polyfills for jsdom.
 *
 * jsdom does not implement the Popover API or the HTMLDialogElement methods
 * (showModal, show, close). This polyfill provides faithful implementations,
 * including timing semantics validated against Chromium via Playwright.
 *
 * Behaviour:
 *  - beforetoggle: sync, cancelable on popover show only. toggle: async task, never cancelable.
 *  - Rapid show/hide coalesces into one toggle event (originalOldState to finalNewState).
 *  - Dialog: showModal/show fire beforetoggle+toggle. close fires toggle then close event.
 *  - Popover open state tracked via `data-popover-open` (no `:popover-open` in jsdom).
 *  - Auto popovers: maintain an open stack, perform light-dismiss on document mousedown
 *    outside the open chain, and dismiss the topmost on Escape.
 *  - On open, removes any inline `opacity: 0` from the popover element so callers that
 *    rely on a `ResizeObserver` reveal callback (e.g. `use-anchor-position`) become
 *    visible in jsdom, where layout-driven RO callbacks never fire.
 *
 * Companion `toBeVisible` patch lives at `./to-be-visible`.
 *
 * Importing this module has the side-effect of patching the relevant
 * prototypes. It is safe to import multiple times; each branch is guarded
 * to avoid overwriting native implementations or re-patching.
 */
export {};