Method SetEmptyString

preclass/capivara/v8/include/v8-function-callback.h:349–353

template <typename T>
void ReturnValue<T>::SetEmptyString() {
  static_assert(std::is_base_of<T, String>::value, "type check");
  using I = internal::Internals;
  *value_ = *I::GetRoot(GetIsolate(), I::kEmptyStringRootIndex);
}

template <typename T>
Isolate* ReturnValue<T>::GetIsolate() const {