[builtins] Also migrate String.prototype.toLowerCase/toUpperCase to C++.

src/bootstrapper.cc

 // Copyright 2014 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.
 
 #include "src/bootstrapper.h"
 
 #include "src/accessors.h"
 #include "src/api-natives.h"
 #include "src/code-stubs.h"
 #include "src/extensions/externalize-string-extension.h"
@@ skipping 1322 matching lines @@
 
     // Install the "constructor" property on the {prototype}.
     JSObject::AddProperty(prototype, factory->constructor_string(), string_fun,
                           DONT_ENUM);
 
     // Install the String.prototype methods.
     SimpleInstallFunction(prototype, "charAt", Builtins::kStringPrototypeCharAt,
                           1, true);
     SimpleInstallFunction(prototype, "charCodeAt",
                           Builtins::kStringPrototypeCharCodeAt, 1, true);
+    // TODO(bmeurer): One day we will want to install the correct i18n functions
+    // here directly instead of first installing the dummy, and overriding those
+    // in i18n.js later.
+    SimpleInstallFunction(prototype, "toLocaleLowerCase",
+                          Builtins::kStringPrototypeToLowerCase, 0, false);
+    SimpleInstallFunction(prototype, "toLocaleUpperCase",
+                          Builtins::kStringPrototypeToUpperCase, 0, false);
+    SimpleInstallFunction(prototype, "toLowerCase",
+                          Builtins::kStringPrototypeToLowerCase, 0, false);
+    SimpleInstallFunction(prototype, "toUpperCase",
+                          Builtins::kStringPrototypeToUpperCase, 0, false);
     SimpleInstallFunction(prototype, "trim", Builtins::kStringPrototypeTrim, 0,
                           false);
     SimpleInstallFunction(prototype, "trimLeft",
                           Builtins::kStringPrototypeTrimLeft, 0, false);
     SimpleInstallFunction(prototype, "trimRight",
                           Builtins::kStringPrototypeTrimRight, 0, false);
   }
 
   {
     // --- S y m b o l ---
@@ skipping 2442 matching lines @@
 }
 
 
 // Called when the top-level V8 mutex is destroyed.
 void Bootstrapper::FreeThreadResources() {
   DCHECK(!IsActive());
 }
 
 }  // namespace internal
 }  // namespace v8