This directory used to contain the binary dependencies, but they were removed during a cleanup associated with importing the project into google/protobuf repository. Before we figure a better way to manage the dependencies, you will have to manually download the dependencies to be able to build the test projects:
lib/Microsoft.Silverlight.Testing/lib/NUnit/lib/proto.exeAfter that, you should be able to fully build the C# protobufs Visual Studio solutions.
TODO(jtattermusch): the way we pull in dependencies needs to change