Remove --harmony-async-await runtime flag

test/debugger/regress/regress-5610.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 --turbo
+// Flags: --turbo
 
 var Debug = debug.Debug;
 var step_count = 0;
 
 function listener(event, execState, eventData, data) {
   if (event != Debug.DebugEvent.Break) return;
   try {
     var line = execState.frame(0).sourceLineText();
     print(line);
     var [match, expected_count, step] = /\/\/ B(\d) (\w+)$/.exec(line);
     assertEquals(step_count++, parseInt(expected_count));
     if (step != "Continue") execState.prepareStep(Debug.StepAction[step]);
   } catch (e) {
     print(e, e.stack);
     quit(1);
   }
 }
 
 Debug.setListener(listener);
 
 async function f() {
   var a = 1;
   debugger;          // B0 StepNext
   print(1);          // B1 StepNext
   return a;          // B2 StepNext
 }                    // B3 Continue
 
 f();