I have two packages: webserver and utils which provides assets to webserver.
The webserver needs access to static files inside uti
Use the Resource class, a new class in Dart SDK 1.12.
Usage example:
var resource = new Resource('package:myapp/myfile.txt');
var contents = await resource.loadAsString();
print(contents);
This works on the VM, as of 1.12.
However, this doesn't directly address your need to get to the actual File entity, from a package: URI. Given the Resource class today, you'd have to route the bytes from loadAsString() into the HTTP server's Response object.