* Make it possible to override the FLUTTER_TEST env variable without unsetting it.
* Switch to using platform instead of Platform.
* Document the bindings, and introduce tests that initialize multiple WidgetsBindings with different environments.
* Add tests for the flutter platform test.
* Add license headers
* Fix lints
* Remove trailing whitespace
* Respond to Jonahs comments
* Respond to Ians comments
* Mock out the HttpServer in flutter_platform_test
* Mock out the HttpServer in flutter_platform_test
* Explain why we mock out the HttpServer in flutter_platform_test
