Port 2.0: Prep tests for CoreCLR/CoreRT [Serializable] cleanup

[karelz]

We need to port PR dotnet/corefx#20035

cc @morganbr @stephentoub

[tarekgh]

@karelz this issue would be fixed after merging dotnet/corefx#20035 or is there more work need to be done here? it is not clear to me what need to be done here?

[karelz]

After merging dotnet/corefx#20035 we will have the fix in master = 2.1. We need to port it to 2.0. That's what this issue tracks.
Does it answer your question?

[tarekgh]

@morganbr I assigned this one to you. please let me know if you are not the one going to port it to 2.0.

[tarekgh]

@morganbr would you port the changes before the end of the week?

[danmoseley]

@morganbr there seems no work here.