ES6 symbols: Introduce Symbol class, along with abstract Name class

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 73 matching lines @@
         'test-parsing.cc',
         'test-platform-tls.cc',
         'test-profile-generator.cc',
         'test-random.cc',
         'test-regexp.cc',
         'test-reloc-info.cc',
         'test-serialize.cc',
         'test-sockets.cc',
         'test-spaces.cc',
         'test-strings.cc',
+        'test-symbols.cc',
         'test-strtod.cc',
         'test-thread-termination.cc',
         'test-threads.cc',
         'test-unbound-queue.cc',
         'test-utils.cc',
         'test-version.cc',
         'test-weakmaps.cc'
       ],
       'conditions': [
         ['v8_target_arch=="ia32"', {
@@ skipping 90 matching lines @@
             '<@(_outputs)',
             'TEST',  # type
             'off',  # compression
             '<@(file_list)',
           ],
         }
       ],
     },
   ],
 }