env;
{
// 这个是进入引擎，使用VMState类，在析构的时候，离开引擎
ENTER_V8(isolate);
v8::Handle proxy_template = global_template;
i::Handle proxy_constructor;
i::Handle global_constructor;
if (!global_template.IsEmpty()) {
// Make sure that the global_template has a constructor.
global_constructor =
EnsureConstructor(Utils::OpenHandle(*global_template));
// Create a fresh template for the global proxy object.
proxy_template = ObjectTemplate::New();
proxy_constructor =
EnsureConstructor(Utils::OpenHandle(*proxy_template));
// Set the global template to be the prototype template of
// global proxy template.
proxy_constructor->set_prototype_template(
*Utils::OpenHandle(*global_template));
// Migrate security handlers from global_template to
// proxy_template. Temporarily removing access check
// information from the global template.
if (!global_constructor->access_check_info()->IsUndefined()) {
proxy_constructor->set_access_check_info(
global_constructor->access_check_info());
proxy_constructor->set_needs_access_check(
global_constructor->needs_access_check());
global_constructor->set_needs_access_check(false);
global_constructor->set_access_check_info(
isolate->heap()->undefined_value());
}
}
// Create the environment.
env = isolate->bootstrapper()->CreateEnvironment(
isolate,
Utils::OpenHandle(*global_object, true),
proxy_template,
extensions);
// Restore the access check info on the global template.
if (!global_template.IsEmpty()) {
ASSERT(!global_constructor.is_null());
ASSERT(!proxy_constructor.is_null());
global_constructor->set_access_check_info(
proxy_constructor->access_check_info());
global_constructor->set_needs_access_check(
proxy_constructor->needs_access_check());
}
isolate->runtime_profiler()->Reset();
}
// Leave V8.
if (env.is_null()) {
return Persistent();
}
return Persistent(Utils::ToLocal(env));
} 
