v0.5.0

Changed

• A compound that can never match inside a complex functional-pseudo-class
  argument now ends the chain, instead of leaving the reversed-axis test that
  carried the compounds to its left in the output: e:is(f > g:is()) is
  e[0] rather than e[0 and parent::*[self::f]], and
  li:nth-child(2 of f > g:is()) is li[0] rather than an expression naming
  the dead chain twice, once inside a count() over every preceding sibling.
  Both selected the same (empty) node set before, so no caller gets a
  different answer. This is the fold XPathExpr::condition already applied to
  a single compound's own conjunction (a:hover[x] is a[0]), reaching the
  conjunction that Translator::argument_condition assembles across
  compounds; it applies through :is(), :where(), :not() and the nth
  of S lists, while :has() builds a path and was never affected. Only the
  compounds to the left of the dead one go — e:is(f > g:is() > h) keeps
  its self::h and is e[self::h and parent::*[0]] — and a 0 that is
  already alone inside its axis bracket stays put, so e:is(f:is() > g)
  remains e[self::g and parent::*[0]] and still shows which compound is the
  impossible one.