Allow debugger to step into Map and Set forEach callbacks

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 88 matching lines @@
     throw MakeTypeError('incompatible_method_receiver',
                         ['Set.prototype.forEach', this]);
   }
 
   if (!IS_SPEC_FUNCTION(f)) {
     throw MakeTypeError('called_non_callable', [f]);
   }
 
   var iterator = %SetCreateIterator(this, ITERATOR_KIND_VALUES);
   var entry;
+  var stepping = %_DebugCallbackSupportsStepping(f);
   while (!(entry = %SetIteratorNext(iterator)).done) {
+    if (stepping) %DebugPrepareStepInIfStepping(f);
     %_CallFunction(receiver, entry.value, entry.value, this, f);
   }
 }
 
 
 // -------------------------------------------------------------------
 
 function SetUpSet() {
   %CheckIsBootstrapping();
 
@@ skipping 88 matching lines @@
     throw MakeTypeError('incompatible_method_receiver',
                         ['Map.prototype.forEach', this]);
   }
 
   if (!IS_SPEC_FUNCTION(f)) {
     throw MakeTypeError('called_non_callable', [f]);
   }
 
   var iterator = %MapCreateIterator(this, ITERATOR_KIND_ENTRIES);
   var entry;
+  var stepping = %_DebugCallbackSupportsStepping(f);
   while (!(entry = %MapIteratorNext(iterator)).done) {
+    if (stepping) %DebugPrepareStepInIfStepping(f);
     %_CallFunction(receiver, entry.value[1], entry.value[0], this, f);
   }
 }
 
 
 // -------------------------------------------------------------------
 
 function SetUpMap() {
   %CheckIsBootstrapping();
 
   %SetCode($Map, MapConstructor);
   %FunctionSetPrototype($Map, new $Object());
   %SetProperty($Map.prototype, "constructor", $Map, DONT_ENUM);
 
   %FunctionSetLength(MapForEach, 1);
 
   // Set up the non-enumerable functions on the Map prototype object.
   InstallGetter($Map.prototype, "size", MapGetSizeJS);
   InstallFunctions($Map.prototype, DONT_ENUM, $Array(
     "get", MapGetJS,
     "set", MapSetJS,
     "has", MapHasJS,
     "delete", MapDeleteJS,
     "clear", MapClearJS,
     "forEach", MapForEach
   ));
 }
 
 SetUpMap();