Function deduplicate

test/fixtures/snapshot/typescript.js:1014–1019

* Deduplicates an unsorted array. * @param equalityComparer An `EqualityComparer` used to determine if two values are duplicates. * @param comparer An optional `Comparer` used to sort entries before comparison, though the * result will remain in the original order in `array`.

(array, equalityComparer, comparer)

     * result will remain in the original order in `array`.
     */
    function deduplicate(array, equalityComparer, comparer) {
        return array.length === 0 ? [] :
            array.length === 1 ? array.slice() :
                comparer ? deduplicateRelational(array, equalityComparer, comparer) :
                    deduplicateEquality(array, equalityComparer);
    }
    ts.deduplicate = deduplicate;
    /**
     * Deduplicates an array that has already been sorted.