* Moved the default BinaryMessenger instance to ServicesBinding
This reverts commit 821602aef3.
* Added assertion in defaultBinaryMessenger. Also fixed the devicelab tests.
The files in this directory are used as part of tests in the
flutter_tools package. Some are here because here these tests need a
pubspec.yaml that references the flutter framework (which is
intentionally not true of the flutter_tools package). Others are
here mostly out of peer pressure.