Fix gn build

BUILD.gn

 # Copyright 2014 The Chromium Authors. All rights reserved.
 # Use of this source code is governed by a BSD-style license that can be
 # found in the LICENSE file.
 
 # TODO(jochen): These will need to be user-settable to support standalone V8
 # builds.
 v8_compress_startup_data = "off"
 v8_deprecation_warnings = false
 v8_enable_disassembler = false
 v8_enable_gdbjit = false
 v8_enable_handle_zapping = true
 v8_enable_i18n_support = true
 v8_enable_verify_heap = false
 v8_interpreted_regexp = false
 v8_object_print = false
 v8_postmortem_support = false
-v8_use_default_platform = true
+v8_use_default_platform = false
 v8_use_snapshot = true
 v8_use_external_startup_data = false
 v8_enable_extra_checks = is_debug
 v8_target_arch = cpu_arch
 v8_random_seed = "314159265"
 
 
 ###############################################################################
 # Configurations
 #
@@ skipping 310 matching lines @@
     ":generate_trig_table",
     ":run_mksnapshot",
     ":v8_base",
   ]
 
   sources = [
     "$target_gen_dir/libraries.cc",
     "$target_gen_dir/experimental-libraries.cc",
     "$target_gen_dir/trig-table.cc",
     "$target_gen_dir/snapshot.cc",
+    "src/snapshot-common.cc",
   ]
 
   configs -= [ "//build/config/compiler:chromium_code" ]
   configs += [ "//build/config/compiler:no_chromium_code" ]
   configs += [ ":internal_config", ":features", ":toolchain" ]
 }
 
 source_set("v8_base") {
   visibility = ":*"  # Only targets in this file can depend on this.
 
@@ skipping 700 matching lines @@
     deps = [
       ":v8_base",
       ":v8_nosnapshot",
     ]
   }
 
   direct_dependent_configs = [ ":external_config" ]
 }
 
 }