Run some slow tail call tests only for fast configurations.

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 246 matching lines @@
   'call-counts': [SKIP],
 
   # Slow tests.
   'copy-on-write-assert': [PASS, SLOW],
   'debug-scopes': [PASS, SLOW],
   'es7/object-observe': [PASS, ['mode == debug', SLOW]],
   'numops-fuzz-part*': [PASS, ['mode == debug', SLOW]],
   'readonly': [PASS, SLOW],
   'regress/regress-1200351': [PASS, ['mode == debug', SLOW]],
   'regress/regress-crbug-474297': [PASS, ['mode == debug', SLOW]],
+  'es6/tail-call-megatest*': [PASS, FAST_VARIANTS],
 
   # TODO(titzer): correct WASM adapter frame alignment on arm64
   'wasm/*': [PASS, ['arch == arm64', SKIP]],
   'wasm/asm-wasm': [PASS, ['arch in [arm, arm64, mips, mipsel, mips64, mips64el]', SKIP]],
 
   # TODO(branelson): Figure out why ignition + asm->wasm fails embenchen.
   'wasm/embenchen/*': [PASS, ['ignition == True', SKIP]],
 
   # TODO(bradnelson) Fix and re-enable.
   'wasm/embenchen/copy': [FAIL],  # wrong answer
@@ skipping 607 matching lines @@
 ##############################################################################
 ['gcov_coverage', {
   # Tests taking too long.
   'array-functions-prototype-misc': [SKIP],
 
   # Stack overflow.
   'big-array-literal': [SKIP],
 }],  # 'gcov_coverage'
 
 ]