[System.Text.Json] Fix bug complex properties

[MarcoRossignoli]

fixes https://github.com/dotnet/corefx/issues/37536
fixes https://github.com/dotnet/corefx/issues/37567

Suggest me more test case if needed.

cc: @steveharter @ahsonkhan

[MarcoRossignoli]

unrelated ci fail https://mc.dot.net/#/user/dotnet-bot/pr~2Fdotnet~2Fcorefx~2Frefs~2Fpull~2F37586~2Fmerge/test~2Ffunctional~2Fcli~2F/20190510.15

[MarcoRossignoli]

If I understood well we should return true only if we're sure to be at the end of json object root

[ahsonkhan]

fixes #37567

Suggest me more test case if needed.

I would add a test with properties that have private setters like the one that was stated in the original issue (both for top-level properties, and for complex properties/nested).

[MarcoRossignoli]

Close because I confirm that update #37578 fix bug my tests passed. cc: @steveharter @ahsonkhan

[ahsonkhan]

Close because I confirm that update #37578 fix bug my tests passed.

Both of them? #37567 as well?

@steveharter consider adding the test cases from @MarcoRossignoli from this PR into yours.

[MarcoRossignoli]

Both of them? #37567 as well?

I think so I did some test with @steveharter clone and sample on #37567 works