Add GN split_list function

tools/gn/gn.gyp

 {
   'variables': {
     'chromium_code': 1,
   },
   'targets': [
     {
       'target_name': 'gn_lib',
       'type': 'static_library',
       'dependencies': [
         '../../base/base.gyp:base',
@@ skipping 120 matching lines @@
         'ninja_toolchain_writer.cc',
         'ninja_toolchain_writer.h',
         'ninja_utils.cc',
         'ninja_utils.h',
         'ninja_writer.cc',
         'ninja_writer.h',
         'operators.cc',
         'operators.h',
         'output_file.cc',
         'output_file.h',
+        'parse_node_value_adapter.cc',
+        'parse_node_value_adapter.h',
         'parse_tree.cc',
         'parse_tree.h',
         'parser.cc',
         'parser.h',
         'path_output.cc',
         'path_output.h',
         'pattern.cc',
         'pattern.h',
         'pool.cc',
         'pool.h',
@@ skipping 158 matching lines @@
           'dependencies': [
             'gn_unittests',
           ],
           'includes': [ '../../build/isolate.gypi' ],
           'sources': [ 'gn_unittests.isolate' ],
         },
       ],
     }],
   ],
 }