[Bindings] Create and use V8 context snapshots

third_party/WebKit/Source/bindings/modules/v8/v8.gni

 # 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.
 
 import("custom/custom.gni")
 
 # Make the files absolute so they can be imported to anywhere.
 bindings_modules_v8_files =
     get_path_info([
                     "serialization/SerializedScriptValueForModulesFactory.cpp",
                     "serialization/SerializedScriptValueForModulesFactory.h",
                     "serialization/V8ScriptValueDeserializerForModules.cpp",
                     "serialization/V8ScriptValueDeserializerForModules.h",
                     "serialization/V8ScriptValueSerializerForModules.cpp",
                     "serialization/V8ScriptValueSerializerForModules.h",
                     "DictionaryHelperForModules.cpp",
                     "ModuleBindingsInitializer.cpp",
                     "ModuleBindingsInitializer.h",
                     "ToV8ForModules.h",
                     "V8BindingForModules.cpp",
                     "V8BindingForModules.h",
+                    "V8ContextSnapshotExternalReferences.h",
                     "wasm/WasmResponseExtensions.cpp",
                     "wasm/WasmResponseExtensions.h",
                     "WebGLAny.cpp",
                     "WebGLAny.h",
                   ],
                   "abspath") + bindings_modules_v8_custom_files
 
 bindings_modules_v8_unittest_files =
     get_path_info([
                     "serialization/V8ScriptValueSerializerForModulesTest.cpp",
                     "V8BindingForModulesTest.cpp",
                   ],
                   "abspath")