It's not just runtime code generation. If it were just that, you could have a browser without a JIT.
But they also forbid execution of code that doesn't ship with the app itself. So you can't have a JIT-less browser that runs any JS at all.
But for Servo none of that would matter anyway, because it's written in Rust. And Apple's policies only allow binaries whose source code is C, C++, Objective-C or Swift, last I checked. So Servo, and any other program written in Rust, is not allowed in the app store period, no matter whether it's a web browser or not and what it does with JS.
But they also forbid execution of code that doesn't ship with the app itself. So you can't have a JIT-less browser that runs any JS at all.
But for Servo none of that would matter anyway, because it's written in Rust. And Apple's policies only allow binaries whose source code is C, C++, Objective-C or Swift, last I checked. So Servo, and any other program written in Rust, is not allowed in the app store period, no matter whether it's a web browser or not and what it does with JS.