The sort cell, filter funnel/popover and filter predicate move to
components/tableHeader.tsx so a non-DataTable body can render under the same
headers — the playlist manager's drag-reorderable list needs the headers
without inheriting DataTable's internal ordering state.
FilterPopover reaches module scope in the process. It was declared inside
DataTable's body, so it was a new component type on every render and React
remounted it on each keystroke; verified against the pre-change build, where
the input's DOM node is replaced on all four keystrokes of a test word.
Also picks up two things that live in this markup: aria-sort on the sortable
headers, and a real hit target on the filter funnel (it was 14x14).
peter
89000538d4