Auto import on .dart folder

Hi,
I am using `flutter_gen` to produce localization. It's like `Gallary` localization described [here](https://github.com/flutter/gallery/blob/master/lib/l10n/README.md).
When I want to import my localization that placed at `package:flutter_gen/gen_l10n/localizations.dart` by `Alt + Inter`, there is no recommendation to import from there.
Is there a way to fix this, or have to import that manually?

Reproduce the missing import suggestion for `package:flutter_gen/gen_l10n/localizations.dart` in a Flutter project using `flutter_gen`, starting from the Alt+Enter action. Done means the IDE recommends that localization import when referenced from a `.dart` file; the issue does not name implementation files or tests.

Written by the indexing model from the issue text.