ES6: Add support for Map/Set forEach

src/objects-visiting.cc

 // Copyright 2011 the V8 project authors. All rights reserved.
 // Redistribution and use in source and binary forms, with or without
 // modification, are permitted provided that the following conditions are
 // met:
 //
 //     * Redistributions of source code must retain the above copyright
 //       notice, this list of conditions and the following disclaimer.
 //     * Redistributions in binary form must reproduce the above
 //       copyright notice, this list of conditions and the following
 //       disclaimer in the documentation and/or other materials provided
@@ skipping 145 matching lines @@
     case JS_CONTEXT_EXTENSION_OBJECT_TYPE:
     case JS_GENERATOR_OBJECT_TYPE:
     case JS_MODULE_TYPE:
     case JS_VALUE_TYPE:
     case JS_DATE_TYPE:
     case JS_ARRAY_TYPE:
     case JS_GLOBAL_PROXY_TYPE:
     case JS_GLOBAL_OBJECT_TYPE:
     case JS_BUILTINS_OBJECT_TYPE:
     case JS_MESSAGE_OBJECT_TYPE:
+    case JS_SET_ITERATOR_TYPE:
+    case JS_MAP_ITERATOR_TYPE:
       return GetVisitorIdForSize(kVisitJSObject,
                                  kVisitJSObjectGeneric,
                                  instance_size);
 
     case JS_FUNCTION_TYPE:
       return kVisitJSFunction;
 
     case HEAP_NUMBER_TYPE:
 #define EXTERNAL_ARRAY_CASE(Type, type, TYPE, ctype, size)                     \
     case EXTERNAL_##TYPE##_ARRAY_TYPE:
@@ skipping 306 matching lines @@
 
 
 template Object* VisitWeakList<JSArrayBuffer>(
     Heap* heap, Object* list, WeakObjectRetainer* retainer, bool record_slots);
 
 
 template Object* VisitWeakList<AllocationSite>(
     Heap* heap, Object* list, WeakObjectRetainer* retainer, bool record_slots);
 
 } }  // namespace v8::internal