Move builtin JavaScript sources into own directory.

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 91 matching lines @@
           'include_dirs': ['../third_party/wasm'],
         }],
       ],
     },
     {
       'target_name': 'd8_js2c',
       'type': 'none',
       'variables': {
         'js_files': [
           'd8.js',
-          'macros.py',
+          'js/macros.py',
         ],
       },
       'conditions': [
         [ 'want_separate_host_toolset==1', {
           'toolsets': ['host'],
         }, {
           'toolsets': ['target'],
         }]
       ],
       'actions': [
@@ skipping 30 matching lines @@
             '../build/isolate.gypi',
           ],
           'sources': [
             'd8.isolate',
           ],
         },
       ],
     }],
   ],
 }