benchmark: use node v4 syntax in common.js

Using new syntax such as `...args` means that the benchmark suite can't
be used with older node versions. This changes the `...args` syntax to a
good old `Array.prototype.slice`.

Refs: https://github.com/nodejs/node/pull/8932#issuecomment-252924107
PR-URL: https://github.com/nodejs/node/pull/9064


Reviewed-By: James M Snell <jasnell@gmail.com>
Reviewed-By: Brian White <mscdex@mscdex.net>