In our source page highlighting, we were generating `<span class="op">`
tags for all "operators", including e.g. `<` `>` around generic
parameters, `*`, `&`. This contributed significantly to DOM size, but
we don't actually style `.op` except in the ayu theme.
Remove the styles for `.op` in ayu, and stop generating the `<span>`s.
This reduces DOM size of an example page[1] from 265,938 HTML elements
to 242,165 elements, a 9% reduction.
[1]:
https://doc.rust-lang.org/nightly/src/core/up/up/stdarch/crates/core_arch/src/x86/avx512f.rs.html
This test does not test the output as well as I would like, but I think
I am limited by htmldocck. I would really just like to strip all the
HTML tags from the output for the sake of the different `@has` checks,
but that doesn't seem to be currently possible.