Migrate some case conversion functions from JS to CPP builtins

src/v8.gyp

 # Copyright 2012 the V8 project authors. All rights reserved.
 # Redistribution and use in source and binary forms, with or without
 # modification, are permitted provided that the following conditions are
 # met:
 #
 #     * Redistributions of source code must retain the above copyright
 #       notice, this list of conditions and the following disclaimer.
 #     * Redistributions in binary form must reproduce the above
 #       copyright notice, this list of conditions and the following
 #       disclaimer in the documentation and/or other materials provided
@@ skipping 507 matching lines @@
         'builtins/builtins-promise.h',
         'builtins/builtins-proxy.cc',
         'builtins/builtins-reflect.cc',
         'builtins/builtins-regexp.cc',
         'builtins/builtins-regexp-gen.cc',
         'builtins/builtins-regexp-gen.h',
         'builtins/builtins-sharedarraybuffer.cc',
         'builtins/builtins-sharedarraybuffer-gen.cc',
         'builtins/builtins-string.cc',
         'builtins/builtins-string-gen.cc',
+        'builtins/builtins-intl.cc',
         'builtins/builtins-symbol.cc',
         'builtins/builtins-symbol-gen.cc',
         'builtins/builtins-typedarray.cc',
         'builtins/builtins-typedarray-gen.cc',
         'builtins/builtins-utils.h',
         'builtins/builtins-utils-gen.h',
         'builtins/builtins-wasm-gen.cc',
         'builtins/builtins.cc',
         'builtins/builtins.h',
         'cached-powers.cc',
@@ skipping 1961 matching lines @@
       'conditions': [
         ['want_separate_host_toolset_mkpeephole==1', {
           'toolsets': ['host'],
         }, {
           'toolsets': ['target'],
         }],
       ],
     },
   ],
 }