benchmark: add benchmark for destructuring object

PR-URL: https://github.com/nodejs/node/pull/8680
Reviewed-By: Brian White <mscdex@mscdex.net>
Reviewed-By: James M Snell <jasnell@gmail.com>
Reviewed-By: Ilkka Myller <ilkka.myller@nodefield.com>

benchmark/es/destructuring-object-bench.js

@@ -0,0 +1,49 @@
+'use strict';
+
+const common = require('../common.js');
+
+const bench = common.createBenchmark(main, {
+  method: ['normal', 'destructureObject'],
+  millions: [100]
+});
+
+function runNormal(n) {
+  var i = 0;
+  var o = { x: 0, y: 1 };
+  bench.start();
+  for (; i < n; i++) {
+    /* eslint-disable no-unused-vars */
+    var x = o.x;
+    var y = o.y;
+    var r = o.r || 2;
+    /* eslint-enable no-unused-vars */
+  }
+  bench.end(n / 1e6);
+}
+
+function runDestructured(n) {
+  var i = 0;
+  var o = { x: 0, y: 1 };
+  bench.start();
+  for (; i < n; i++) {
+    /* eslint-disable no-unused-vars */
+    var { x, y, r = 2 } = o;
+    /* eslint-enable no-unused-vars */
+  }
+  bench.end(n / 1e6);
+}
+
+function main(conf) {
+  const n = +conf.millions * 1e6;
+
+  switch (conf.method) {
+    case 'normal':
+      runNormal(n);
+      break;
+    case 'destructureObject':
+      runDestructured(n);
+      break;
+    default:
+      throw new Error('Unexpected method');
+  }
+}