Move benching into testing. (denoland/deno_std#258)

Original: 4de86f04de

testing/bench_example.ts

@@ -0,0 +1,29 @@
+// https://deno.land/std/testing/bench.ts
+import { BenchmarkTimer, bench, runIfMain } from "./bench.ts";
+
+// Basic
+bench(function forIncrementX1e9(b: BenchmarkTimer) {
+  b.start();
+  for (let i = 0; i < 1e9; i++);
+  b.stop();
+});
+
+// Reporting average measured time for $runs runs of func
+bench({
+  name: "runs100ForIncrementX1e6",
+  runs: 100,
+  func(b) {
+    b.start();
+    for (let i = 0; i < 1e6; i++);
+    b.stop();
+  }
+});
+
+// Itsabug
+bench(function throwing(b) {
+  b.start();
+  // Throws bc the timer's stop method is never called
+});
+
+// Bench control
+runIfMain(import.meta, { skip: /throw/ });