Notable traits tooltip is laid out underneath subsequent methods

This happens because `contain: layout` (#102253) establishes a new stacking context

https://doc.rust-lang.org/nightly/nightly-rustc/rustc_middle/hir/map/struct.Map.html#method.parent_owner_iter
![parent_iter's notable trait tooltip underflowing is_lhs](https://user-images.githubusercontent.com/1830331/193452774-ddadf1a3-fdf9-436d-b927-47eda94d0328.png)
