The same if-check occurs inside calc_parallel_worker_threads as well, so one can drop the if on this caller level.
```
if (FLAG_IS_DEFAULT(ParallelGCThreads)) {
_parallel_worker_threads = WorkerPolicy::calc_parallel_worker_threads();
} else {
_parallel_worker_threads = ParallelGCThreads;
}
```
```
if (FLAG_IS_DEFAULT(ParallelGCThreads)) {
_parallel_worker_threads = WorkerPolicy::calc_parallel_worker_threads();
} else {
_parallel_worker_threads = ParallelGCThreads;
}
```