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

src/builtins.h

 // Copyright 2011 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.
 
 #ifndef V8_BUILTINS_H_
 #define V8_BUILTINS_H_
 
 #include "src/base/flags.h"
 #include "src/handles.h"
 
@@ skipping 154 matching lines @@
   V(ReflectGetOwnPropertyDescriptor, kNone)                    \
   V(ReflectGetPrototypeOf, kNone)                              \
   V(ReflectHas, kNone)                                         \
   V(ReflectIsExtensible, kNone)                                \
   V(ReflectOwnKeys, kNone)                                     \
   V(ReflectPreventExtensions, kNone)                           \
   V(ReflectSet, kNone)                                         \
   V(ReflectSetPrototypeOf, kNone)                              \
                                                                \
   V(StringFromCharCode, kNone)                                 \
+  V(StringPrototypeToLowerCase, kNone)                         \
+  V(StringPrototypeToUpperCase, kNone)                         \
   V(StringPrototypeTrim, kNone)                                \
   V(StringPrototypeTrimLeft, kNone)                            \
   V(StringPrototypeTrimRight, kNone)                           \
                                                                \
   V(SymbolConstructor, kNone)                                  \
   V(SymbolConstructor_ConstructStub, kTarget)                  \
                                                                \
   V(HandleApiCall, kTargetAndNewTarget)                        \
   V(HandleApiCallAsFunction, kNone)                            \
   V(HandleApiCallAsConstructor, kNone)                         \
@@ skipping 516 matching lines @@
   friend class BuiltinFunctionTable;
   friend class Isolate;
 
   DISALLOW_COPY_AND_ASSIGN(Builtins);
 };
 
 }  // namespace internal
 }  // namespace v8
 
 #endif  // V8_BUILTINS_H_