Merged: Disallow tail calls from async functions and generators

test/mjsunit/regress/regress-639270.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: --allow-natives-syntax --turbo
+// Flags: --allow-natives-syntax --es-staging --ignition-staging --turbo
 
-function f() {
-  var o = {};
-  o.a = 1;
-}
-function g() {
-  var o = { ['a']: function(){} };
-  f();
-}
-f();
-f();
+"use strict";
+
+var g = (async () => { return JSON.stringify() });
+
+g();
+g();
 %OptimizeFunctionOnNextCall(g);
 g();