beta regression: svgdom struct is private

[alexcrichton]

Discovered by crater:

$ git clone https://github.com/RazrFalcon/resvg
$ cd resvg
$ git reset --hard v0.3.0
$ cargo +beta build

cc @petrochenkov

[petrochenkov]

This is an expected bug-fix regression, it was previously found by the crater run in #55884 as well.
It has a dedicated test - https://github.com/rust-lang/rust/blob/master/src/test/ui/imports/issue-55884-2.rs.

[alexcrichton]

👍

cc @RazrFalcon, just to make sure you're aware!

[RazrFalcon]

Thanks. Not sure how this should be fixed. It actually works in master, but not in v0.13. And I wan't to make v0.13.1.