My first thought is I'm mildly skeptical that this will end up being granular enough or detailed enough to actually be useful in practice, but if it does, it co

My first thought is I'm mildly skeptical that this will end up being granular enough or detailed enough to actually be useful in practice, but if it does, it could be very useful. I'm pretty happy to see Firefox pushing its dev tools in this direction. They've done a really great job with layout and styling tools, but their JS dev tools have lagged behind Chrome's. So even if this particular effort doesn't pan out for some reason, it's still very encouraging. They're not just carbon-copying Chrome, and they're not just sitting back and ignoring the dev tools; they're trying to push them forward in some interesting ways.