Then replace them with a crash or popup ("Line <x> was reached but shouldn't be reachable. Please report this." or whatever) Phoning home without permission go

Then replace them with a crash or popup ("Line <x> was reached but shouldn't be reachable. Please report this." or whatever) Phoning home without permission goes against the entire concept of a secure browser. Have you ever seen the underhanded C contests? There are far too many ways for something like this to turn nasty. Especially given there's inherent plausible deniability.