Given the publicity of some recent webkit bugs I start getting mildly nervous about the outdated webkit on my box. After the latest update didn't improve things, I started poking a bit more, and it turns out that the bug title was *very much* over-generalising.
The crashes very specifically occur on one screen of a two-screen "ZaphodHeads" setup on nouveau. It is actually the case that DISPLAY=display-host:0.0 luakit runs just fine, whereas DISPLAY=display-host:0.1 luakit shows the crashes. I have to admit this badly stumps me. I'm still reluctant to delve into either of webkit or nouveau, so... does someone perhaps have a theory what might possibly cause such a thing that I could try before I start digging?