Make debugger step into bound callbacks passed to Array.forEach.

src/collection.js

 // Copyright 2012 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.
 
 "use strict";
 
 // This file relies on the fact that the following declaration has been made
 // in runtime.js:
 // var $Array = global.Array;
 
@@ skipping 87 matching lines @@
   }
   var needs_wrapper = false;
   if (IS_NULL_OR_UNDEFINED(receiver)) {
     receiver = %GetDefaultReceiver(f) || receiver;
   } else {
     needs_wrapper = SHOULD_CREATE_WRAPPER(f, receiver);
   }
 
   var iterator = new SetIterator(this, ITERATOR_KIND_VALUES);
   var key;
-  var stepping = DEBUG_IS_ACTIVE && %DebugCallbackSupportsStepping(f);
+  var stepping = DEBUG_IS_STEPPING();
   var value_array = [UNDEFINED];
   while (%SetIteratorNext(iterator, value_array)) {
     if (stepping) %DebugPrepareStepInIfStepping(f);
     key = value_array[0];
     var new_receiver = needs_wrapper ? ToObject(receiver) : receiver;
     %_CallFunction(new_receiver, key, key, this, f);
   }
 }
 
 
@@ skipping 121 matching lines @@
     throw MakeTypeError('called_non_callable', [f]);
   }
   var needs_wrapper = false;
   if (IS_NULL_OR_UNDEFINED(receiver)) {
     receiver = %GetDefaultReceiver(f) || receiver;
   } else {
     needs_wrapper = SHOULD_CREATE_WRAPPER(f, receiver);
   }
 
   var iterator = new MapIterator(this, ITERATOR_KIND_ENTRIES);
-  var stepping = DEBUG_IS_ACTIVE && %DebugCallbackSupportsStepping(f);
+  var stepping = DEBUG_IS_STEPPING();
   var value_array = [UNDEFINED, UNDEFINED];
   while (%MapIteratorNext(iterator, value_array)) {
     if (stepping) %DebugPrepareStepInIfStepping(f);
     var new_receiver = needs_wrapper ? ToObject(receiver) : receiver;
     %_CallFunction(new_receiver, value_array[1], value_array[0], this, f);
   }
 }
 
 
 // -------------------------------------------------------------------
@@ skipping 15 matching lines @@
     "get", MapGetJS,
     "set", MapSetJS,
     "has", MapHasJS,
     "delete", MapDeleteJS,
     "clear", MapClearJS,
     "forEach", MapForEach
   ));
 }
 
 SetUpMap();