Added parallel marking threads.

tools/gyp/v8.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 364 matching lines @@
             '../../src/liveedit.cc',
             '../../src/liveedit.h',
             '../../src/log-inl.h',
             '../../src/log-utils.cc',
             '../../src/log-utils.h',
             '../../src/log.cc',
             '../../src/log.h',
             '../../src/macro-assembler.h',
             '../../src/mark-compact.cc',
             '../../src/mark-compact.h',
+            '../../src/marking-thread.h',
+            '../../src/marking-thread.cc',
             '../../src/messages.cc',
             '../../src/messages.h',
             '../../src/natives.h',
             '../../src/objects-debug.cc',
             '../../src/objects-inl.h',
             '../../src/objects-printer.cc',
             '../../src/objects-visiting.cc',
             '../../src/objects-visiting.h',
             '../../src/objects.cc',
             '../../src/objects.h',
@@ skipping 652 matching lines @@
             }],
           ],
           'dependencies': [
             'v8'
           ],
         },
       ],
     }],
   ],
 }