Instantiations with type literals are not properly cached/shared

[vladima]

Currently every occurrence of type literal in the source code creates new anonymous type which breaks caching of instantiations. #11934 covers one case (for {} type literal) however in general the problem still exists (#10451)

[ahejlsberg]

I believe this has been fixed with the type alias instantiation caching logic that was added in #12114. Certainly the problem in #10451 no longer exists. I think we can close this one.