Merge pull request #2983 from dotty-staging/fix-2250

Fix #2250: add green test

Author: nicolasstucki

tests/pos/i2250.scala

@@ -0,0 +1,5 @@
+class T {
+  def foo(any: AnyRef): Unit = {
+    any.asInstanceOf[Array[_]].iterator
+  }
+}