Update benchmark test dependencies

test/bench/random.js

@@ -70,7 +70,7 @@ new Benchmark.Suite('random').add('imagemagick', {
 }).on('cycle', function(event) {
   console.log(String(event.target));
 }).on('complete', function() {
-  var winner = this.filter('fastest').pluck('name');
+  var winner = this.filter('fastest').map('name');
   assert.strictEqual('sharp', String(winner), 'sharp was slower than ' + winner);
   console.dir(sharp.cache());
 }).run();