[js-perf-test] Add a basic async-await microbenchmark

test/js-perf-test/AsyncAwait/baseline-naive-promises.js

+// Copyright 2016 the V8 project authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+
+new BenchmarkSuite('BaselineNaivePromises', [1000], [
+  new Benchmark('Basic', false, false, 0, Basic, Setup),
+]);
+
+var a,b,c,d,e,f,g,h,i,j,x;
+
+function Setup() {
+  x = Promise.resolve();
+
+  j = function j(p) { return p; };
+  i = function i(p) {
+    return p.then(j)
+            .then(j)
+            .then(j)
+            .then(j)
+            .then(j)
+            .then(j)
+            .then(j)
+            .then(j)
+            .then(j)
+            .then(j);
+  };
+  h = function h(p) { return p; };
+  g = function g(p) { return p; };
+  f = function f(p) { return p; };
+  e = function e(p) { return p; };
+  d = function d(p) { return p; };
+  c = function c(p) { return p; };
+  b = function b(p) { return p; };
+  a = function a(p) { return p; };
+
+  %RunMicrotasks();
+}
+
+function Basic() {
+  x.then(j)
+   .then(i)
+   .then(h)
+   .then(g)
+   .then(f)
+   .then(e)
+   .then(d)
+   .then(c)
+   .then(b)
+   .then(a);
+  %RunMicrotasks();
+}