Out of curiosity - do the codebases for modern browser engines routinely get subjected to static analysis tools and runtime tools like asan (Address sanitizer)

Out of curiosity - do the codebases for modern browser engines routinely get subjected to static analysis tools and runtime tools like asan (Address sanitizer) / valgrind? Are there categories of UAF that would not be caught with valgrind / asan? Or is it the case that the test suites do not have sufficient coverage to exhibit the issues?