Remove --harmony-async-await runtime flag

test/mjsunit/es8/async-function-stacktrace.js

Index: test/mjsunit/es8/async-function-stacktrace.js
diff --git a/test/mjsunit/harmony/async-function-stacktrace.js b/test/mjsunit/es8/async-function-stacktrace.js
similarity index 99%
rename from test/mjsunit/harmony/async-function-stacktrace.js
rename to test/mjsunit/es8/async-function-stacktrace.js
index 5ab20881a668e0b82c2ede89cd44af1135130f8f..ab6dd2633b9ac1e50525f72432d5895b3bc893b0 100644
--- a/test/mjsunit/harmony/async-function-stacktrace.js
+++ b/test/mjsunit/es8/async-function-stacktrace.js
@@ -2,8 +2,6 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
-// Flags: --harmony-async-await
-
 async function test(func, funcs) {
   try {
     await func();