The problem is that you are telling it to use the 3.5 version of the compiler. Implicit line-continuation was not added as a feature until version 4.0 of the .NET Framework, so you'll need to use the version 4.0 (or later) compiler if you want the implicit line-continuation to work. Try changing this:
providerOptions.Add("CompilerVersion", "v3.5"); // .NET v3.5
To this:
providerOptions.Add("CompilerVersion", "v4.0"); // .NET v4.0