tResult_ be ! ToBoolean(? Call(_predicate_, _thisArg_, &laquo; _kValue_, ùîΩ(_k_), _O_ &raquo;)).
      1. If _testResult_ is *true*, return ùîΩ(_k_).
      1. Set _k_ to _k_ - 1.
    1. Return *-1*<sub>ùîΩ</sub>.
  </emu-alg>
  <p>This function is not generic. The *this* value must be an object with a [[TypedArrayName]] internal slot.</p>
</emu-clause>
