For starters, no one said the only problem with Chromium is C++. But it certainly contributes with some of the problems (specially those related to security). And, no, these bugs don't come from "noob programmers." They come from experienced engineers.
Then you just mention that removed some "unnecessary and unwanted" code. According to what standard? You? Would be nice if you went into specifics and provided some benchmarks. Instead we are forced to take the word that a user "rustfreeforme" (wonder which biases they have) made an polished fork, instead of, possibly, mangling the code in such a way that just benefits them and screws other people.
Finally, Rust doesn't: make the code more complex than C++, specially if using the STL; doesn't make compilations slower, as C++ and Rust compilation times are on par (and keep in mind Rust is very unoptimized here, where as C++ is slow by design).