Remove --harmony-async-await runtime flag

test/debugger/debug/es8/async-function-debug-evaluate.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.
 
-// Flags: --harmony-async-await
-
 var Debug = debug.Debug;
 var breakPointCount = 0;
 
 function listener(event, exec_state, event_data, data) {
   if (event != Debug.DebugEvent.Break) return;
   ++breakPointCount;
   try {
     if (breakPointCount === 1) {
       assertEquals(
           "inner", exec_state.frame(0).evaluate("inner").value());
@@ skipping 113 matching lines @@
 
 test().
 then(x => {
   Debug.setListener(null);
 }).
 catch(error => {
   print(error.stack);
   quit(1);
   Debug.setListener(null);
 });