Capture the Success companion object as well as its class (#24747)

The absence of this is something that caught me out, and others.

akka-stream-tests/src/test/scala/akka/stream/scaladsl/ActorRefSourceSpec.scala

@@ -99,6 +99,19 @@ class ActorRefSourceSpec extends StreamSpec {
       s.expectComplete()
     }
 
+    "signal buffered elements and complete the stream after receiving a Status.Success companion" in assertAllStagesStopped {
+      val s = TestSubscriber.manualProbe[Int]()
+      val ref = Source.actorRef(3, OverflowStrategy.fail).to(Sink.fromSubscriber(s)).run()
+      val sub = s.expectSubscription
+      ref ! 1
+      ref ! 2
+      ref ! 3
+      ref ! Status.Success
+      sub.request(10)
+      s.expectNext(1, 2, 3)
+      s.expectComplete()
+    }
+
     "not buffer elements after receiving Status.Success" in assertAllStagesStopped {
       val s = TestSubscriber.manualProbe[Int]()
       val ref = Source.actorRef(3, OverflowStrategy.dropBuffer).to(Sink.fromSubscriber(s)).run()

akka-stream/src/main/scala/akka/stream/scaladsl/Source.scala

@@ -529,7 +529,10 @@ object Source {
    */
   def actorRef[T](bufferSize: Int, overflowStrategy: OverflowStrategy): Source[T, ActorRef] =
     actorRef(
-      { case akka.actor.Status.Success(_) ⇒ },
+      {
+        case akka.actor.Status.Success    ⇒
+        case akka.actor.Status.Success(_) ⇒
+      },
       { case akka.actor.Status.Failure(cause) ⇒ cause },
       bufferSize, overflowStrategy)