Optimize case conversion with icu_case_mapping

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 2103 matching lines @@
     if (normalizationForm === -1) {
       throw %make_range_error(kNormalizationForm,
           %_Call(ArrayJoin, NORMALIZATION_FORMS, ', '));
     }
 
     return %StringNormalize(s, normalizationForm);
   }
 );
 
 function ToLowerCaseI18N() {
-  if (!IS_UNDEFINED(new.target)) {
-    throw %make_type_error(kOrdinaryFunctionCalledAsConstructor);
-  }
   CHECK_OBJECT_COERCIBLE(this, "String.prototype.toLowerCase");
-  var s = TO_STRING(this);
-  return %StringToLowerCaseI18N(s);
+  return %StringToLowerCaseI18N(TO_STRING(this));
 }
 
 function ToUpperCaseI18N() {
-  if (!IS_UNDEFINED(new.target)) {
-    throw %make_type_error(kOrdinaryFunctionCalledAsConstructor);
-  }
   CHECK_OBJECT_COERCIBLE(this, "String.prototype.toUpperCase");
-  var s = TO_STRING(this);
-  return %StringToUpperCaseI18N(s);
+  return %StringToUpperCaseI18N(TO_STRING(this));
 }
 
 function ToLocaleLowerCaseI18N(locales) {
-  if (!IS_UNDEFINED(new.target)) {
-    throw %make_type_error(kOrdinaryFunctionCalledAsConstructor);
-  }
   CHECK_OBJECT_COERCIBLE(this, "String.prototype.toLocaleLowerCase");
   return LocaleConvertCase(TO_STRING(this), locales, false);
 }
 
 %FunctionSetLength(ToLocaleLowerCaseI18N, 0);
 
 function ToLocaleUpperCaseI18N(locales) {
-  if (!IS_UNDEFINED(new.target)) {
-    throw %make_type_error(kOrdinaryFunctionCalledAsConstructor);
-  }
   CHECK_OBJECT_COERCIBLE(this, "String.prototype.toLocaleUpperCase");
   return LocaleConvertCase(TO_STRING(this), locales, true);
 }
 
 %FunctionSetLength(ToLocaleUpperCaseI18N, 0);
 
 %FunctionRemovePrototype(ToLowerCaseI18N);
 %FunctionRemovePrototype(ToUpperCaseI18N);
 %FunctionRemovePrototype(ToLocaleLowerCaseI18N);
 %FunctionRemovePrototype(ToLocaleUpperCaseI18N);
@@ skipping 100 matching lines @@
   }
 );
 
 %FunctionRemovePrototype(FormatDateToParts);
 
 utils.Export(function(to) {
   to.FormatDateToParts = FormatDateToParts;
 });
 
 })