When FF 57 came out I was surprised at the new debugger, much better than the old one. But turns out it's still useless. I can't put a breakpoint in the middle

When FF 57 came out I was surprised at the new debugger, much better than the old one. But turns out it's still useless. I can't put a breakpoint in the middle of a WebGL game and expect it to work like in Chrome. The last dev version is even more useless, the "break on exception" button is missing.