Introduce FieldIndex to unify and abstract property/field offset

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 327 matching lines @@
         '../../src/extensions/gc-extension.h',
         '../../src/extensions/statistics-extension.cc',
         '../../src/extensions/statistics-extension.h',
         '../../src/extensions/trigger-failure-extension.cc',
         '../../src/extensions/trigger-failure-extension.h',
         '../../src/factory.cc',
         '../../src/factory.h',
         '../../src/fast-dtoa.cc',
         '../../src/fast-dtoa.h',
         '../../src/feedback-slots.h',
+        '../../src/field-index.cc',
+        '../../src/field-index.h',
+        '../../src/field-index-inl.h',
         '../../src/fixed-dtoa.cc',
         '../../src/fixed-dtoa.h',
         '../../src/flag-definitions.h',
         '../../src/flags.cc',
         '../../src/flags.h',
         '../../src/frames-inl.h',
         '../../src/frames.cc',
         '../../src/frames.h',
         '../../src/full-codegen.cc',
         '../../src/full-codegen.h',
@@ skipping 877 matching lines @@
         }],
         ['v8_compress_startup_data=="bz2"', {
           'libraries': [
             '-lbz2',
           ]
         }],
       ],
     },
   ],
 }