swift

19d05abf - [Concurrency] Fix `stripConcurrency` to avoid dropping parameter isolation

[Concurrency] Fix `stripConcurrency` to avoid dropping parameter isolation Special case for `isolated` parameters, because even though the isolation was dropped, the parameter itself was left with `isolated` bit set. `dropIsolation` is intended only for mangling of `@preconcurrency` declarations and isolated parameters don't contribute to the type so it's save to keep the original isolation here. Resolves: rdar://171075466