message: refactor(forkJoin): remove unnecessary property assignment
diff: @@ -172,7 +172,6 @@ class ForkJoinSubscriber<T, R> extends OuterSubscriber<T, T> {
  const innerSubscription = subscribeToResult(this, source, null, i);
  if (innerSubscription) {
  - (innerSubscription as any).outerIndex = i;
  this.add(innerSubscription);
  }
  }
  