Also, I've noticed that the `identifier` attribute on the touch events seems to not behave the same as it does on WebKit-based browsers. In Gecko, it seems to go `0, 1, 2, ...` and the `identifier` gets re-used on subsequent `touchstart` events. I didn't notice this until just the other day, as I'm used to `identifier` being a sequential, unique value (like a timestamp). So, knowing that now, I'm pretty sure there are a couple little optimizations that can be made based on that assumption that it will be `0, 1, 2, ...`.