Use same blob format for internal and external snapshots.

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.
 
 # Because standalone V8 builds are not supported, assume this is part of a
 # Chromium build.
 import("//build/module_args/v8.gni")
 
 # TODO(jochen): These will need to be user-settable to support standalone V8
 # builds.
@@ skipping 339 matching lines @@
   deps = [
     ":js2c",
     ":js2c_experimental",
     ":v8_base",
   ]
 
   sources = [
     "$target_gen_dir/libraries.cc",
     "$target_gen_dir/experimental-libraries.cc",
     "src/snapshot-empty.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_snapshot") {
   visibility = [ ":*" ]  # Only targets in this file can depend on this.
 
   deps = [
     ":js2c",
     ":js2c_experimental",
     ":run_mksnapshot",
     ":v8_base",
   ]
 
   sources = [
     "$target_gen_dir/libraries.cc",
     "$target_gen_dir/experimental-libraries.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" ]
 }
 
 if (v8_use_external_startup_data) {
   source_set("v8_external_snapshot") {
     visibility = [ ":*" ]  # Only targets in this file can depend on this.
@@ skipping 494 matching lines @@
     "src/scanner.cc",
     "src/scanner.h",
     "src/scopeinfo.cc",
     "src/scopeinfo.h",
     "src/scopes.cc",
     "src/scopes.h",
     "src/serialize.cc",
     "src/serialize.h",
     "src/small-pointer-list.h",
     "src/smart-pointers.h",
+    "src/snapshot-common.cc",
     "src/snapshot-source-sink.cc",
     "src/snapshot-source-sink.h",
     "src/snapshot.h",
     "src/string-builder.cc",
     "src/string-builder.h",
     "src/string-search.cc",
     "src/string-search.h",
     "src/string-stream.cc",
     "src/string-stream.h",
     "src/strtod.cc",
@@ skipping 544 matching lines @@
     deps = [
       ":v8_base",
       ":v8_nosnapshot",
     ]
   }
 
   direct_dependent_configs = [ ":external_config" ]
 }
 
 }