[debug-wrapper] Further extend the debug wrapper

test/debugger/debug/regress/regress-crbug-605581.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: --expose-debug-as debug
 
 var Debug = debug.Debug;
 var exception = null;
 
 function listener(event, exec_state, event_data, data) {
   if (event != Debug.DebugEvent.Break) return;
   try {
     assertThrows(() => exec_state.frame(0).evaluate("bar.baz"), ReferenceError);
   } catch (e) {
     exception = e;
   }
 }
 
 Debug.setListener(listener);
 
 (function() {
   debugger;    // bar is still in TDZ at this point.
   let bar = 1;
   (x => bar);  // force bar to be context-allocated.
 })();
 
 Debug.setListener(null);
 assertNull(exception);