[runtime] Add %ToString and %_ToString and remove the TO_STRING builtin.

src/runtime.js

 // Copyright 2006-2008 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.
 
 // This files contains runtime support implemented in JavaScript.
 
 // CAUTION: Some of the functions specified in this file are called
 // directly from compiled code. These are the functions with names in
 // ALL CAPS. The compiled code passes the first argument in 'this'.
 
@@ skipping 845 matching lines @@
   "sar_strong_builtin", SAR_STRONG,
   "shl_builtin", SHL,
   "shl_strong_builtin", SHL_STRONG,
   "shr_builtin", SHR,
   "shr_strong_builtin", SHR_STRONG,
   "stack_overflow_builtin", STACK_OVERFLOW,
   "string_add_left_builtin", STRING_ADD_LEFT,
   "string_add_right_builtin", STRING_ADD_RIGHT,
   "sub_builtin", SUB,
   "sub_strong_builtin", SUB_STRONG,
-  "to_string_builtin", TO_STRING,
 ]);
 
 %InstallToContext([
   "concat_iterable_to_array", ConcatIterableToArray,
   "non_number_to_number", NonNumberToNumber,
   "non_string_to_string", NonStringToString,
   "to_integer_fun", ToInteger,
   "to_length_fun", ToLength,
   "to_number_fun", ToNumber,
   "to_primitive", ToPrimitive,
   "to_string_fun", ToString,
 ]);
 
 utils.Export(function(to) {
   to.ToBoolean = ToBoolean;
   to.ToLength = ToLength;
   to.ToNumber = ToNumber;
   to.ToPrimitive = ToPrimitive;
   to.ToString = ToString;
 });
 
 })