leak-tracker: Support pure Dart package

[Solido]

Hi,

leak-tracker is an important tool in the dart world as the language is moving from being mainly front to also model rich world logic.

I'm working on a large package that would greatly benefits from memory insights while dealing with deep data structures and operations.

Thanks!

[polina-c]

Thanks for filing it! How about design discussion? I sent you message in Twitter to schedule.