[esnext] prototype runtime implementation for async functions

BUILD.gn

 # Copyright 2014 The Chromium Authors. All rights reserved.
 # Use of this source code is governed by a BSD-style license that can be
 # found in the LICENSE file.
 
 import("//build/config/android/config.gni")
 import("//build/config/arm.gni")
 import("//build/config/mips.gni")
 import("//build/config/sanitizers/sanitizers.gni")
 
 if (is_android) {
@@ skipping 400 matching lines @@
   # The script depends on this other script, this rule causes a rebuild if it
   # changes.
   inputs = [
     "tools/jsmin.py",
   ]
 
   # NOSORT
   sources = [
     "src/js/macros.py",
     "src/messages.h",
+    "src/js/harmony-async-await.js",
     "src/js/harmony-atomics.js",
     "src/js/harmony-regexp-exec.js",
     "src/js/harmony-sharedarraybuffer.js",
     "src/js/harmony-simd.js",
     "src/js/harmony-species.js",
     "src/js/harmony-unicode-regexps.js",
     "src/js/harmony-string-padding.js",
     "src/js/promise-extra.js",
   ]
 
@@ skipping 1776 matching lines @@
   ]
 
   deps = [
     ":fuzzer_support",
   ]
 
   configs = [
     ":internal_config",
   ]
 }