CSS <try-tactic> keywords for the position-try-fallbacks property
(CSS Anchor Positioning Level 1). Each entry is written verbatim into
the host's position-try-fallbacks style; entries are not resolved
through any cngx mapping table.
The union enumerates both orderings of two-keyword composites
(flip-block flip-inline vs flip-inline flip-block) so consumers
can match the canonical ordering Chrome resolves to when it normalises
the cascaded value. Three-keyword composites are commutative enough
that one form suffices.
Mirrors the precedent in projects/forms/select/shared/select-base.css
which already ships position-try-fallbacks: flip-block, flip-inline, flip-block flip-inline; on select panels.