[builtins] move String.prototype[@@iterator] to C++ builtin

src/contexts.h

 // 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.
 
 #ifndef V8_CONTEXTS_H_
 #define V8_CONTEXTS_H_
 
 #include "src/heap/heap.h"
 #include "src/objects.h"
 
@@ skipping 130 matching lines @@
   V(FAST_TEMPLATE_INSTANTIATIONS_CACHE_INDEX, FixedArray,                      \
     fast_template_instantiations_cache)                                        \
   V(SLOW_TEMPLATE_INSTANTIATIONS_CACHE_INDEX, UnseededNumberDictionary,        \
     slow_template_instantiations_cache)                                        \
   V(FUNCTION_FUNCTION_INDEX, JSFunction, function_function)                    \
   V(GENERATOR_FUNCTION_FUNCTION_INDEX, JSFunction,                             \
     generator_function_function)                                               \
   V(GENERATOR_OBJECT_PROTOTYPE_MAP_INDEX, Map, generator_object_prototype_map) \
   V(INITIAL_ARRAY_PROTOTYPE_INDEX, JSObject, initial_array_prototype)          \
   V(INITIAL_GENERATOR_PROTOTYPE_INDEX, JSObject, initial_generator_prototype)  \
+  V(INITIAL_ITERATOR_PROTOTYPE_INDEX, JSObject, initial_iterator_prototype)    \
   V(INITIAL_OBJECT_PROTOTYPE_INDEX, JSObject, initial_object_prototype)        \
   V(INT16_ARRAY_FUN_INDEX, JSFunction, int16_array_fun)                        \
   V(INT16X8_FUNCTION_INDEX, JSFunction, int16x8_function)                      \
   V(INT32_ARRAY_FUN_INDEX, JSFunction, int32_array_fun)                        \
   V(INT32X4_FUNCTION_INDEX, JSFunction, int32x4_function)                      \
   V(INT8_ARRAY_FUN_INDEX, JSFunction, int8_array_fun)                          \
   V(INT8X16_FUNCTION_INDEX, JSFunction, int8x16_function)                      \
   V(INTERNAL_ARRAY_FUNCTION_INDEX, JSFunction, internal_array_function)        \
   V(ITERATOR_RESULT_MAP_INDEX, Map, iterator_result_map)                       \
   V(JS_ARRAY_FAST_SMI_ELEMENTS_MAP_INDEX, Map,                                 \
@@ skipping 390 matching lines @@
 #endif
 
   STATIC_ASSERT(kHeaderSize == Internals::kContextHeaderSize);
   STATIC_ASSERT(EMBEDDER_DATA_INDEX == Internals::kContextEmbedderDataIndex);
 };
 
 }  // namespace internal
 }  // namespace v8
 
 #endif  // V8_CONTEXTS_H_