Bring what always I bring to protests whenever there is a chance of violence from the non-violent, anti-war, anti-western, pro-terrorist lefties: as little as possible.
I have plenty of good equipment, from subminiature to 4x5, and I always bring the same kit: a 1952 Rolleicord and strap, lens hood, yellow filter, LOTS of fast B&W Pan film, a roll of making tape and two black felt-tipped markers (to mark roll numbers, etc, on the film; also, the good guy counter-protesters may need to touch up their signs), a notepad, several pens (I always loose at least one) and a packet of calling cards.
You don't need a lightmeter; I leave my venerable Lunasix-3 safely at home. Wing the exposure if you have to: when in doubt, overexpose; it's B&W, right? Otherwise, you'll spend your time doing what I used to do...taking lots of meter readings, instead of taking pictures.
Sorry I'm late with the advice; I was busy yesterday shovelling snow off my roof. Keep it in mind for the next leftfest in town