doesn't result in much gain on my machine or my CI server so it's not
the default. On local machine (5800x), went from ~5ms to ~4ms, on my CI
(hetzner ampere altra with 8 vCPUs) went from ~15ms to ~10ms.
uses regex mostly, resulting in a significantly faster execution (old:
~2s, new: ~31ms). Only matches classList.add/remove and class="..."
(won't touch string literal variables or colours), but these weren't
really used anyway. Supports multi-line classList.add/remove, which was
the reason I wrote this anyway (formatting the codebase introduced some
of these).