[builtins] Move StringLastIndexOf to a builtin.

src/js/i18n.js

 // Copyright 2013 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.
 
 // ECMAScript 402 API implementation.
 
 /**
  * Intl object is a single object that has some named properties,
  * all of which are constructors.
  */
@@ skipping 17 matching lines @@
 var InstallGetter = utils.InstallGetter;
 var InternalArray = utils.InternalArray;
 var InternalRegExpMatch;
 var InternalRegExpReplace
 var ObjectHasOwnProperty = utils.ImportNow("ObjectHasOwnProperty");
 var OverrideFunction = utils.OverrideFunction;
 var patternSymbol = utils.ImportNow("intl_pattern_symbol");
 var resolvedSymbol = utils.ImportNow("intl_resolved_symbol");
 var SetFunctionName = utils.SetFunctionName;
 var StringIndexOf;
-var StringLastIndexOf;
 var StringSubstr;
 var StringSubstring;
 
 utils.Import(function(from) {
   ArrayJoin = from.ArrayJoin;
   ArrayPush = from.ArrayPush;
   InternalRegExpMatch = from.InternalRegExpMatch;
   InternalRegExpReplace = from.InternalRegExpReplace;
   StringIndexOf = from.StringIndexOf;
-  StringLastIndexOf = from.StringLastIndexOf;
   StringSubstr = from.StringSubstr;
   StringSubstring = from.StringSubstring;
 });
 
 utils.ImportFromExperimental(function(from) {
   FLAG_intl_extra = from.FLAG_intl_extra;
 });
 
 // Utilities for definitions
 
@@ skipping 250 matching lines @@
     // Remove -u- extension.
     var locale = InternalRegExpReplace(
         GetUnicodeExtensionRE(), requestedLocales[i], '');
     do {
       if (!IS_UNDEFINED(availableLocales[locale])) {
         // Push requested locale not the resolved one.
         %_Call(ArrayPush, matchedLocales, requestedLocales[i]);
         break;
       }
       // Truncate locale if possible, if not break.
-      var pos = %_Call(StringLastIndexOf, locale, '-');
+      var pos = locale.lastIndexOf('-');

[Benedikt Meurer, 2016/09/14 17:02:32]

This is not correct, because this does a lookup of lastIndexOf on locale each
time you executed it. But String.prototype.lastIndexOf is monkey patchable,
which means you might get a different function here. So you really need to
remember the correct function during bootstrapping. Or even better, put it onto
the native context and call it via %StringLastIndexOf(locale, '-') here, as we
do with other initial functions like %ObjectFreeze, etc.

[petermarshall, 2016/09/15 12:19:59]

Added the runtime function back in as we discussed

       if (pos === -1) {
         break;
       }
       locale = %_Call(StringSubstring, locale, 0, pos);
     } while (true);
   }
 
   return matchedLocales;
 }
 
@@ skipping 102 matching lines @@
         GetAnyExtensionRE(), requestedLocales[i], '');
     do {
       if (!IS_UNDEFINED(AVAILABLE_LOCALES[service][locale])) {
         // Return the resolved locale and extension.
         var extensionMatch = InternalRegExpMatch(
             GetUnicodeExtensionRE(), requestedLocales[i]);
         var extension = IS_NULL(extensionMatch) ? '' : extensionMatch[0];
         return {'locale': locale, 'extension': extension, 'position': i};
       }
       // Truncate locale if possible.
-      var pos = %_Call(StringLastIndexOf, locale, '-');
+      var pos = locale.lastIndexOf('-');

[Benedikt Meurer, 2016/09/14 17:02:32]

Same here.

       if (pos === -1) {
         break;
       }
       locale = %_Call(StringSubstring, locale, 0, pos);
     } while (true);
   }
 
   // Didn't find a match, return default.
   return {'locale': GetDefaultICULocaleJS(), 'extension': '', 'position': -1};
 }
@@ skipping 1863 matching lines @@
 %FunctionRemovePrototype(FormatDateToParts);
 
 utils.Export(function(to) {
   to.AddBoundMethod = AddBoundMethod;
   to.FormatDateToParts = FormatDateToParts;
   to.IntlParseDate = IntlParseDate;
   to.IntlParseNumber = IntlParseNumber;
 });
 
 })