[Bindings] Create and use V8 context snapshots

third_party/WebKit/Source/platform/bindings/V8PerContextData.cpp

 /*
  * Copyright (C) 2012 Google Inc. 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
@@ skipping 71 matching lines @@
 }
 
 V8PerContextData* V8PerContextData::From(v8::Local<v8::Context> context) {
   return ScriptState::From(context)->PerContextData();
 }
 
 v8::Local<v8::Object> V8PerContextData::CreateWrapperFromCacheSlowCase(
     const WrapperTypeInfo* type) {
   DCHECK(!error_prototype_.IsEmpty());
 
-  v8::Context::Scope scope(GetContext());
+  v8::Local<v8::Context> context = GetContext();

[Yuki, 2017/06/20 14:20:11]

|context| seems never used again?

[peria, 2017/06/21 07:19:16]

Done.

+  v8::Context::Scope scope(context);
   v8::Local<v8::Function> interface_object = ConstructorForType(type);
+
   CHECK(!interface_object.IsEmpty());
   v8::Local<v8::Object> instance_template =
       V8ObjectConstructor::NewInstance(isolate_, interface_object)
           .ToLocalChecked();
   wrapper_boilerplates_.Set(type, instance_template);
   return instance_template->Clone();
 }
 
 v8::Local<v8::Function> V8PerContextData::ConstructorForTypeSlowCase(
     const WrapperTypeInfo* type) {
@@ skipping 48 matching lines @@
       if (!V8CallBoolean(prototype_object->SetPrototype(
               current_context, error_prototype_.NewLocal(isolate_)))) {
         return v8::Local<v8::Function>();
       }
     }
   }
 
   // Origin Trials
   InstallConditionalFeatures(type, ScriptState::From(current_context),
                              prototype_object, interface_object);
-
   constructor_map_.Set(type, interface_object);
 
   return interface_object;
 }
 
 v8::Local<v8::Object> V8PerContextData::PrototypeForType(
     const WrapperTypeInfo* type) {
   v8::Local<v8::Object> constructor = ConstructorForType(type);
   if (constructor.IsEmpty())
     return v8::Local<v8::Object>();
@@ skipping 30 matching lines @@
 
 void V8PerContextData::ClearData(const char* key) {
   data_map_.erase(key);
 }
 
 V8PerContextData::Data* V8PerContextData::GetData(const char* key) {
   return data_map_.at(key);
 }
 
 }  // namespace blink