Migrate some case conversion functions from JS to CPP builtins

src/bootstrapper.cc

Index: src/bootstrapper.cc
diff --git a/src/bootstrapper.cc b/src/bootstrapper.cc
index 7e0800b0d17f008b47db594a1a0a4ecf76e5ff1b..c87a4beecc75419d0aea9dfc56ec790789a57d15 100644
--- a/src/bootstrapper.cc
+++ b/src/bootstrapper.cc
@@ -1724,10 +1724,7 @@ void Genesis::InitializeGlobal(Handle<JSGlobalObject> global_object,
     SimpleInstallFunction(prototype, "toLocaleUpperCase",
                           Builtins::kStringPrototypeToLocaleUpperCase, 0,
                           false);
-    SimpleInstallFunction(prototype, "toLowerCase",
-                          Builtins::kStringPrototypeToLowerCase, 0, false);
-    SimpleInstallFunction(prototype, "toUpperCase",
-                          Builtins::kStringPrototypeToUpperCase, 0, false);
+
     SimpleInstallFunction(prototype, "valueOf",
                           Builtins::kStringPrototypeValueOf, 0, true);
 
@@ -3829,45 +3826,42 @@ void SetFunction(Handle<JSObject> target, Handle<JSFunction> function,
 }  // namespace
 
 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"));
+  if (FLAG_icu_case_mapping) {
+    // ICU
+    Handle<JSReceiver> exports_container(
+        JSReceiver::cast(native_context()->exports_container()));
 
-  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"));
+    SimpleInstallFunction(string_prototype, "toLowerCase",
+                          Builtins::kStringPrototypeToLowerCaseI18N, 0, false);
+    SimpleInstallFunction(string_prototype, "toUpperCase",
+                          Builtins::kStringPrototypeToUpperCaseI18N, 0, false);
 
-  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_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(
-      JSReceiver::GetProperty(
-          exports_container,
-          factory()->InternalizeUtf8String("ToLocaleUpperCaseI18N"))
-          .ToHandleChecked());
-  SetFunction(string_prototype, to_locale_upper_case,
-              factory()->InternalizeUtf8String("toLocaleUpperCase"));
+    Handle<JSFunction> to_locale_upper_case = Handle<JSFunction>::cast(
+        JSReceiver::GetProperty(
+            exports_container,
+            factory()->InternalizeUtf8String("ToLocaleUpperCaseI18N"))
+            .ToHandleChecked());
+    SetFunction(string_prototype, to_locale_upper_case,
+                factory()->InternalizeUtf8String("toLocaleUpperCase"));
+
+  } else {
+    // Unibrow
+    SimpleInstallFunction(string_prototype, "toLowerCase",
+                          Builtins::kStringPrototypeToLowerCase, 0, false);
+    SimpleInstallFunction(string_prototype, "toUpperCase",
+                          Builtins::kStringPrototypeToUpperCase, 0, false);
+  }
 }
 #endif