[builtins] Move StringIndexOf to a C++ builtin.

src/js/string.js

 // 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.
 
 (function(global, utils) {
 
 %CheckIsBootstrapping();
 
 // -------------------------------------------------------------------
 // Imports
@@ skipping 28 matching lines @@
   CHECK_OBJECT_COERCIBLE(this, "String.prototype.concat");
   var s = TO_STRING(this);
   var len = arguments.length;
   for (var i = 0; i < len; ++i) {
     s = s + TO_STRING(arguments[i]);
   }
   return s;
 }
 
 
-// ECMA-262 section 15.5.4.7
-function StringIndexOf(pattern, position) {  // length == 1
-  CHECK_OBJECT_COERCIBLE(this, "String.prototype.indexOf");
-
-  var subject = TO_STRING(this);
-  pattern = TO_STRING(pattern);
-  var index = TO_INTEGER(position);
-  if (index < 0) index = 0;
-  if (index > subject.length) index = subject.length;
-  return %StringIndexOf(subject, pattern, index);
-}
-
-%FunctionSetLength(StringIndexOf, 1);
-
-
 // ES6 21.1.3.11.
 function StringMatchJS(pattern) {
   CHECK_OBJECT_COERCIBLE(this, "String.prototype.match");
 
   if (!IS_NULL_OR_UNDEFINED(pattern)) {
     var matcher = pattern[matchSymbol];
     if (!IS_UNDEFINED(matcher)) {
       return %_Call(matcher, pattern, this);
     }
   }
@@ skipping 454 matching lines @@
 utils.InstallFunctions(GlobalString, DONT_ENUM, [
   "raw", StringRaw
 ]);
 
 // Set up the non-enumerable functions on the String prototype object.
 utils.InstallFunctions(GlobalString.prototype, DONT_ENUM, [
   "codePointAt", StringCodePointAt,
   "concat", StringConcat,
   "endsWith", StringEndsWith,
   "includes", StringIncludes,
-  "indexOf", StringIndexOf,
   "match", StringMatchJS,
   "repeat", StringRepeat,
   "replace", StringReplace,
   "search", StringSearch,
   "slice", StringSlice,
   "split", StringSplitJS,
   "startsWith", StringStartsWith,
   "toLowerCase", StringToLowerCaseJS,
   "toLocaleLowerCase", StringToLocaleLowerCase,
   "toUpperCase", StringToUpperCaseJS,
@@ skipping 11 matching lines @@
   "small", StringSmall,
   "strike", StringStrike,
   "sub", StringSub,
   "sup", StringSup
 ]);
 
 // -------------------------------------------------------------------
 // Exports
 
 utils.Export(function(to) {
-  to.StringIndexOf = StringIndexOf;
   to.StringMatch = StringMatchJS;
   to.StringReplace = StringReplace;
   to.StringSlice = StringSlice;
   to.StringSplit = StringSplitJS;
 });
 
 })