Fix trait method anchor disappearing before user can click on it A good example of this bug is going to https://doc.rust-lang.org/nightly/nightly-rustc/rustc_hir_analysis/collect/struct.ItemCtxt.html#impl-HirTyLowerer%3C'tcx%3E-for-ItemCtxt%3C'tcx%3E, and then try to click on the `§` anchor of the `tcx` method. The solution to this bug is to simply "glue" the anchor to the method, so when the mouse cursor moves to it, there is no gap between the two, preventing the anchor to disappear (hopefully this explanation doesn't make sense only to me ^^'). First commit fixes the bug by expanding the anchor size. Second commit is a small clean-up of the GUI test. Third commit actually adds the GUI regression test. cc @BoxyUwU r? @camelid