[heap] Move slots buffer into a separate file.

test/cctest/cctest.gyp

 # Copyright 2012 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
 #       disclaimer in the documentation and/or other materials provided
@@ skipping 136 matching lines @@
         'test-parsing.cc',
         'test-platform.cc',
         'test-profile-generator.cc',
         'test-random-number-generator.cc',
         'test-regexp.cc',
         'test-reloc-info.cc',
         'test-representation.cc',
         'test-sampler-api.cc',
         'test-serialize.cc',
         'test-simd.cc',
+        'test-slots-buffer.cc',
         'test-spaces.cc',
         'test-strings.cc',
         'test-symbols.cc',
         'test-strtod.cc',
         'test-thread-termination.cc',
         'test-threads.cc',
         'test-transitions.cc',
         'test-typedarrays.cc',
         'test-types.cc',
         'test-typing-reset.cc',
@@ skipping 154 matching lines @@
             '../../tools/js2c.py',
             '<@(_outputs)',
             'TEST',  # type
             '<@(file_list)',
           ],
         }
       ],
     },
   ],
 }