Rustdoc inlining displays reexported typedefs as discrete types

[ebarnard]

Compare:
http://doc.rust-lang.org/collections/str/type.SendStr.html
to
http://doc.rust-lang.org/std/str/type.SendStr.html

Part of #14462?