Include span for Events, not just BrokenLinks

[jyn514]

Rustdoc currently has code that looks like this (yes, it's awful): https://github.com/rust-lang/rust/blob/6f2e1c65933702186cc681a3772862afa77dd632/src/librustdoc/html/markdown.rs#L1076-L1088

Originally I was hoping I could get rid of it now that BrokenLinks have spans. But the spans are only for the broken links, and rustdoc doesn't get them for [parenthesized](links). Is it possible to add that info to Event? I think that would allow removing it from BrokenLink too, but I'm not 100% sure about that.

As a side note, it looks like pulldown includes the [] in the span - is that intentional? Rustdoc only wants the URL itself, which isn't currently possible: consider [inline][link]. The - in the diff is rustdoc's hacky generated span, the + is pulldown's span.

 LL | /// docs [label][with#anchor#error]
-   |                  ^^^^^^^^^^^^^^^^^ contains invalid anchor
+   |          ^^^^^^^^^^^^^^^^^^^^^^^^^^ contains invalid anchor

[ehuss]

I believe into_offset_iter gives the Range for each Event. Rustdoc uses that in a few places already.

[jyn514]

Oh look at that! Thanks, I just didn't read the docs carefully enough :)