Migrate some case conversion functions from JS to CPP builtins

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/base/ieee754.h"
 #include "src/code-stubs.h"
@@ skipping 3863 matching lines @@
 
 void Genesis::InitializeGlobal_icu_case_mapping() {
   if (!FLAG_icu_case_mapping) return;
 
   Handle<JSReceiver> exports_container(
       JSReceiver::cast(native_context()->exports_container()));
 
   Handle<JSObject> string_prototype(
       JSObject::cast(native_context()->string_function()->prototype()));
 
-  Handle<JSFunction> to_lower_case = Handle<JSFunction>::cast(
-      JSReceiver::GetProperty(
-          exports_container,
-          factory()->InternalizeUtf8String("ToLowerCaseI18N"))
-          .ToHandleChecked());
-  SetFunction(string_prototype, to_lower_case,
-              factory()->InternalizeUtf8String("toLowerCase"));
-
-  Handle<JSFunction> to_upper_case = Handle<JSFunction>::cast(
-      JSReceiver::GetProperty(
-          exports_container,
-          factory()->InternalizeUtf8String("ToUpperCaseI18N"))
-          .ToHandleChecked());
-  SetFunction(string_prototype, to_upper_case,
-              factory()->InternalizeUtf8String("toUpperCase"));
+  {
+    Handle<String> name = factory()->InternalizeUtf8String("toLowerCase");
+    SetFunction(string_prototype,
+                SimpleCreateFunction(isolate(), name,
+                                     Builtins::kStringPrototypeToLowerCaseI18N,
+                                     0, false),
+                name);
+  }
+  {
+    Handle<String> name = factory()->InternalizeUtf8String("toUpperCase");
+    SetFunction(string_prototype,
+                SimpleCreateFunction(isolate(), name,
+                                     Builtins::kStringPrototypeToUpperCaseI18N,
+                                     0, false),
+                name);
+  }
 
   Handle<JSFunction> to_locale_lower_case = Handle<JSFunction>::cast(
       JSReceiver::GetProperty(
           exports_container,
           factory()->InternalizeUtf8String("ToLocaleLowerCaseI18N"))
           .ToHandleChecked());
   SetFunction(string_prototype, to_locale_lower_case,
               factory()->InternalizeUtf8String("toLocaleLowerCase"));
 
   Handle<JSFunction> to_locale_upper_case = Handle<JSFunction>::cast(
@@ skipping 1150 matching lines @@
 }
 
 
 // Called when the top-level V8 mutex is destroyed.
 void Bootstrapper::FreeThreadResources() {
   DCHECK(!IsActive());
 }
 
 }  // namespace internal
 }  // namespace v8