Fix cctest + unittest to work with an external snapshot.

src/d8.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 31 matching lines @@
       'dependencies': [
         '../tools/gyp/v8.gyp:v8',
         '../tools/gyp/v8.gyp:v8_libplatform',
       ],
       # Generated source files need this explicitly:
       'include_dirs+': [
         '..',
       ],
       'sources': [
         'd8.cc',
+        'startup-data-util.h',
+        'startup-data-util.cc'
       ],
       'conditions': [
         [ 'want_separate_host_toolset==1', {
           'toolsets': [ '<(v8_toolset_for_d8)', ],
         }],
         [ 'console=="readline"', {
           'libraries': [ '-lreadline', ],
           'sources': [ 'd8-readline.cc' ],
         }],
         ['(OS=="linux" or OS=="mac" or OS=="freebsd" or OS=="netbsd" \
@@ skipping 67 matching lines @@
             '../tools/js2c.py',
             '<@(_outputs)',
             'D8',
             '<@(js_files)'
           ],
         },
       ],
     }
   ],
 }