Add object-visiting.cc into GYP/XCode/MSVC project files.

tools/gyp/v8.gyp

 # Copyright 2009 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 378 matching lines @@
         '../../src/log.h',
         '../../src/macro-assembler.h',
         '../../src/mark-compact.cc',
         '../../src/mark-compact.h',
         '../../src/memory.h',
         '../../src/messages.cc',
         '../../src/messages.h',
         '../../src/natives.h',
         '../../src/objects-debug.cc',
         '../../src/objects-inl.h',
+        '../../src/objects-visiting.cc',
+        '../../src/objects-visiting.h',
         '../../src/objects.cc',
         '../../src/objects.h',
         '../../src/oprofile-agent.h',
         '../../src/oprofile-agent.cc',
         '../../src/parser.cc',
         '../../src/parser.h',
         '../../src/platform.h',
         '../../src/powers-ten.h',
         '../../src/prettyprinter.cc',
         '../../src/prettyprinter.h',
@@ skipping 329 matching lines @@
       ],
       'conditions': [
         ['OS=="win"', {
           # This could be gotten by not setting chromium_code, if that's OK.
           'defines': ['_CRT_SECURE_NO_WARNINGS'],
         }],
       ],
     },
   ],
 }