Restarts the timer for the bench measurement. This should be called after doing setup work which should not be measured.

Warning: This method should not be used for benchmarks averaging less than 10μs per iteration. In such cases it will be disabled but the call will still have noticeable overhead, resulting in a warning.

Deno.bench("foo", async (t) => {
  const data = await Deno.readFile("data.txt");
  t.start();
  // some operation on `data`...
});