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

test/intl/intl.status

Index: test/intl/intl.status
diff --git a/test/intl/intl.status b/test/intl/intl.status
index 02ee26bc56c097893e8e8abdbbb3b60f00eea6eb..0ca910492898daad2e64d3310491c425a55a0d39 100644
--- a/test/intl/intl.status
+++ b/test/intl/intl.status
@@ -35,6 +35,10 @@
   'date-format/parse-mdyhms': [FAIL],
   'number-format/parse-decimal': [FAIL],
   'number-format/parse-percent': [FAIL],
+
+  # BUG(v8:4476, v8:4477). toLowerCase and toUpperCase fixes
+  # are behind a flag, --icu_case_mapping.
+  'general/case-mapping': [FAIL],
 }],  # ALWAYS
 
 ['arch == arm64 and mode == debug and simulator_run == True', {