Put RegExp js code in strict mode

test/test262/test262.status

 # Copyright 2011 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
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@@ skipping 115 matching lines @@
   'language/expressions/prefix-increment/S11.4.4_A5_*': [FAIL],
 
   # https://code.google.com/p/v8/issues/detail?id=4253
   'language/asi/S7.9_A5.7_T1': [PASS, FAIL_OK],
 
    # https://code.google.com/p/v8/issues/detail?id=4602
   'built-ins/RegExp/prototype/exec/get-sticky-coerce': [FAIL],
   'built-ins/RegExp/prototype/exec/get-sticky-err': [FAIL],
   'built-ins/RegExp/prototype/test/get-sticky-err': [FAIL],
 
-  # https://code.google.com/p/v8/issues/detail?id=4504
-  'built-ins/RegExp/prototype/exec/y-fail-lastindex-no-write': [PASS, FAIL],
-  'built-ins/RegExp/prototype/test/y-fail-lastindex-no-write': [PASS, FAIL],
-
   # https://code.google.com/p/v8/issues/detail?id=4305
   # SKIP rather than FAIL some tests, as they may check for an exception which
   # happens to be thrown for some other reason (e.g,
   # built-ins/RegExp/prototype/Symbol.match/builtin-failure-set-lastindex-err)
   'built-ins/RegExp/prototype/Symbol.match/*': [SKIP],
   'built-ins/String/prototype/match/invoke-builtin-match': [FAIL],
 
   # https://code.google.com/p/v8/issues/detail?id=4343
   'built-ins/RegExp/prototype/Symbol.replace/*': [SKIP],
 
@@ skipping 473 matching lines @@
   'language/statements/generators/yield-as-statement': [FAIL],
   'language/statements/generators/yield-as-yield-operand': [FAIL],
   'language/statements/generators/yield-newline': [FAIL],
   'language/statements/generators/yield-star-before-newline': [FAIL],
 
   # TODO(4680,rmcilroy): Test262Error: Expected a RangeError to be thrown but no exception was thrown at all
   'built-ins/Date/prototype/toISOString/15.9.5.43-0-13': [FAIL],
 }],  # ignition == True
 
 ]