Apparently we crash a benchmark from Lucidchart, I couldn't see a link to download the benchmark so I don't know any more details. From the hacker news discussion (http://news.ycombinator.com/item?id=4788601): "Interestingly, the part that crashed Firefox was one of the simpler tests--typing a bunch of text content in, then resizing and rotating the shapes that contain that text. Firefox didn't give any details as to why it crashed. The only thing I could even measure that would lead to a crash is memory usage. I just re-ran the test and watched the process's memory usage. It hovered in the 300-400MB range during the first third of the test. Then, during the test I describe, memory usage rocketed to around 1GB, at which point the browser crashed hard." So maybe another canvas/memory usage bug? Possibly we've fixed this already, 16 is getting kinda old. I will email them to get more details.
Couldn't find an email address, so left a comment on the article to get in touch.
I haven't had any contact from the guys behind the benchmark (beyond a single comment on their page, which I replied to but got not reply top in turn). I can't analyse this without code, or at least some more details, and it doesn't look like we're going to get that, so I'm going to close this, if anyone objects, or has suggestions for how to approach this (or even better, you're associated with the benchmark and want to give us something to work with), please reopen (or email me to do so). Thanks.