[runtime] Replace %to_string_fun with %_ToString.

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 68 matching lines @@
   V(MAKE_RANGE_ERROR_INDEX, JSFunction, make_range_error)                 \
   V(MAKE_TYPE_ERROR_INDEX, JSFunction, make_type_error)                   \
   V(NON_NUMBER_TO_NUMBER_INDEX, JSFunction, non_number_to_number)         \
   V(NON_STRING_TO_STRING_INDEX, JSFunction, non_string_to_string)         \
   V(REFLECT_APPLY_INDEX, JSFunction, reflect_apply)                       \
   V(REFLECT_CONSTRUCT_INDEX, JSFunction, reflect_construct)               \
   V(SPREAD_ARGUMENTS_INDEX, JSFunction, spread_arguments)                 \
   V(SPREAD_ITERABLE_INDEX, JSFunction, spread_iterable)                   \
   V(TO_LENGTH_FUN_INDEX, JSFunction, to_length_fun)                       \
   V(TO_NUMBER_FUN_INDEX, JSFunction, to_number_fun)                       \
-  V(TO_PRIMITIVE_INDEX, JSFunction, to_primitive)                         \
-  V(TO_STRING_FUN_INDEX, JSFunction, to_string_fun)
+  V(TO_PRIMITIVE_INDEX, JSFunction, to_primitive)
 
 
 #define NATIVE_CONTEXT_JS_BUILTINS(V)                                       \
   V(ADD_BUILTIN_INDEX, JSFunction, add_builtin)                             \
   V(ADD_STRONG_BUILTIN_INDEX, JSFunction, add_strong_builtin)               \
   V(APPLY_PREPARE_BUILTIN_INDEX, JSFunction, apply_prepare_builtin)         \
   V(BIT_AND_BUILTIN_INDEX, JSFunction, bit_and_builtin)                     \
   V(BIT_AND_STRONG_BUILTIN_INDEX, JSFunction, bit_and_strong_builtin)       \
   V(BIT_OR_BUILTIN_INDEX, JSFunction, bit_or_builtin)                       \
   V(BIT_OR_STRONG_BUILTIN_INDEX, JSFunction, bit_or_strong_builtin)         \
@@ skipping 538 matching lines @@
   static bool IsBootstrappingOrGlobalObject(Isolate* isolate, Object* object);
 #endif
 
   STATIC_ASSERT(kHeaderSize == Internals::kContextHeaderSize);
   STATIC_ASSERT(EMBEDDER_DATA_INDEX == Internals::kContextEmbedderDataIndex);
 };
 
 } }  // namespace v8::internal
 
 #endif  // V8_CONTEXTS_H_