[debug-wrapper] Further extend the debug wrapper

test/debugger/debug/regress/regress-4309-2.js

 // Copyright 2015 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: --expose-debug-as debug --allow-natives-syntax
 
 var Debug = debug.Debug;
 
 var exception = null;
 
 function listener(event, exec_state, event_data, data) {
   if (event != Debug.DebugEvent.Break) return;
   try {
     var scope = exec_state.frame().scope(0);
     assertEquals(5, scope.scopeObject().property("i").value().value());
   } catch (e) {
     exception = e;
   }
 }
 
 function f() {
   eval('var i = 5');
   debugger;
 }
 
 f();
 f();
 
 %OptimizeFunctionOnNextCall(f);
 Debug.setListener(listener);
 
 f();
 
 assertNull(exception);