Removed dart:uri imports

[Here is the announcement](https://groups.google.com/a/dartlang.org/forum/#!topic/misc/pHyoawHOhU0)


I tried to run your tests, but got only the CLI tests going (they all passed fine).

I installed the `browser` package, and tried running the tests in the browser but got some errors I didn't know how to debug.

It would be nice if you could add some information in your readme on how tests are run.

Thanks