Use ICU case conversion/transliterator for case conversion behind a flag

test/test262/test262.status

 # Copyright 2011 the V8 project authors. All rights reserved.
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 # modification, are permitted provided that the following conditions are
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 #     * Redistributions of source code must retain the above copyright
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@@ skipping 109 matching lines @@
   'built-ins/RegExp/prototype/Symbol.split/*': [SKIP],
 
   # https://code.google.com/p/v8/issues/detail?id=4360
   'intl402/Collator/10.1.1_1': [FAIL],
   'intl402/DateTimeFormat/12.1.1_1': [FAIL],
   'intl402/NumberFormat/11.1.1_1': [FAIL],
 
   # https://code.google.com/p/v8/issues/detail?id=4361
   'intl402/Collator/10.1.1_a': [FAIL],
 
-  # https://code.google.com/p/v8/issues/detail?id=4476
-  'built-ins/String/prototype/toLocaleLowerCase/special_casing_conditional': [FAIL],
-  'built-ins/String/prototype/toLocaleLowerCase/supplementary_plane': [FAIL],
-  'built-ins/String/prototype/toLowerCase/special_casing_conditional': [FAIL],
-  'built-ins/String/prototype/toLowerCase/supplementary_plane': [FAIL],
-  'built-ins/String/prototype/toLocaleUpperCase/supplementary_plane': [FAIL],
-  'built-ins/String/prototype/toUpperCase/supplementary_plane': [FAIL],
-
   # https://code.google.com/p/v8/issues/detail?id=4477
   'intl402/String/prototype/toLocaleLowerCase/special_casing_Azeri': [FAIL],
   'intl402/String/prototype/toLocaleLowerCase/special_casing_Lithuanian': [FAIL],
   'intl402/String/prototype/toLocaleLowerCase/special_casing_Turkish': [FAIL],
   'intl402/String/prototype/toLocaleUpperCase/special_casing_Azeri': [FAIL],
   'intl402/String/prototype/toLocaleUpperCase/special_casing_Lithuanian': [FAIL],
   'intl402/String/prototype/toLocaleUpperCase/special_casing_Turkish': [FAIL],
 
   # https://bugs.chromium.org/p/v8/issues/detail?id=4628
   'language/eval-code/non-definable-function-with-variable': [FAIL],
@@ skipping 216 matching lines @@
   'built-ins/Promise/prototype/then/deferred-is-resolved-value': [SKIP],
 }],  # asan == True
 
 ['asan == True or msan == True or tsan == True', {
   # https://bugs.chromium.org/p/v8/issues/detail?id=4639
   # The failed allocation causes an asan/msan/tsan error
   'built-ins/ArrayBuffer/allocation-limit': [SKIP],
 }],  # asan == True or msan == True or tsan == True
 
 ]