ES6: Add support for Map.prototype.forEach and Set.prototype.forEach

src/objects-visiting.h

 // Copyright 2012 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 80 matching lines @@
   V(Symbol)                   \
   V(Oddball)                  \
   V(Code)                     \
   V(Map)                      \
   V(Cell)                     \
   V(PropertyCell)             \
   V(SharedFunctionInfo)       \
   V(JSFunction)               \
   V(JSWeakMap)                \
   V(JSWeakSet)                \
+  V(JSMapIterator)            \
+  V(JSSetIterator)            \
   V(JSArrayBuffer)            \
   V(JSTypedArray)             \
   V(JSDataView)               \
   V(JSRegExp)
 
   // For data objects, JS objects and structs along with generic visitor which
   // can visit object of any size we provide visitors specialized by
   // object size in words.
   // Ids of specialized visitors are declared in a linear order (without
   // holes) starting from the id of visitor specialized for 2 words objects
@@ skipping 382 matching lines @@
 // access the next-element pointers.
 template <class T>
 Object* VisitWeakList(Heap* heap,
                       Object* list,
                       WeakObjectRetainer* retainer,
                       bool record_slots);
 
 } }  // namespace v8::internal
 
 #endif  // V8_OBJECTS_VISITING_H_