Reformat file. Organize imports by scope when package imports are used.

[ph55]

Description

Package imports are used inside internal package called flutter_core.
Reformat file given following settings and imports inside package file:

Current Behavior

When "Optimize Imports" checkbox is checked external package like http treated the same way as the current package flutter_core and sorted alphabetically only.

Expected Behavior

When "Optimize Imports" checkbox is checked it should first organize by scope:

1. Dart core libraries.
2. Non-project external packages.
3. Project files including package imports.

And only then organize each of the blocks alphabetically:

[stevemessick]

I think this is working as intended. However, this behavior is controlled by the Dart analysis server. If you think it should be changed, please open an issue with the Dart SDK. (Sorry, I used to be able to move issues but no longer can.)