Revert of X87: disable the regress-undefined-nan test case for x87.

test/mjsunit/mjsunit.status

 # Copyright 2012 the V8 project authors. All rights reserved.
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 # modification, are permitted provided that the following conditions are
 # met:
 #
 #     * Redistributions of source code must retain the above copyright
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@@ skipping 548 matching lines @@
   'math-floor-of-div-minus-zero': [SKIP],
 }],  # 'arch == mipsel or arch == mips'
 
 ##############################################################################
 ['arch == mips', {
   # Flaky with TF.
   'mirror-script': [PASS, NO_VARIANTS],
 }],  # 'arch == mips'
 
 ##############################################################################
-['arch == x87', {
-  # Turbofan will hit the known issue that x87 changes sNaN to qNaN by default.
-  'regress-undefined-nan': [SKIP],
-}],  # 'arch == x87'
-
-##############################################################################
 ['arch == mips64el or arch == mips64', {
 
   # Slow tests which times out in debug mode.
   'try': [PASS, ['mode == debug', SKIP]],
   'debug-scripts-request': [PASS, ['mode == debug', SKIP]],
   'array-constructor': [PASS, ['mode == debug', SKIP]],
 
   # Times out often in release mode on MIPS.
   'compiler/regress-stacktrace-methods': [PASS, PASS, ['mode == release', TIMEOUT]],
   'array-splice': [PASS, TIMEOUT],
@@ skipping 135 matching lines @@
   'd8-worker-sharedarraybuffer': [SKIP],
 }],  # 'predictable == True'
 
 ##############################################################################
 ['arch == ppc and simulator_run == True or arch == ppc64 and simulator_run == True', {
 
   # take too long with the simulator.
   'regress/regress-1132': [SKIP],
 }],  # 'arch == ppc and simulator_run == True'
 ]