The first two issues (JIT code compilation and integer overflow/underflow) add up to a significant fraction of the crashing bugs in Gecko that have security exp

The first two issues (JIT code compilation and integer overflow/underflow) add up to a significant fraction of the crashing bugs in Gecko that have security exposure. I can't provide specific numbers, but both are well over 10% of that subset of security bugs. On the correctness of unsafe code, we have very few instances where Servo will actually crash (as opposed to panic and unwind "gracefully"), but they've overwhelmingly been in unsafe code blocks when we weren't properly respecting lifetimes and caused a use after free. For interactive applications, the ability to incrementally reflow the page (say, after an element's value for the display property is changed) is crucial. Modern browser engines have a ton of code that tries to minimize the amount of reflow performed (and sometimes loses correctness!), because it's really easy to accidentally reflow too much and fail to maintain 60fps. We of course hope that throwing parallelism at layout will solve some of this in Servo, but having a more principled approach to the problem of recomputation is interesting, too.