Fix scala/bug#10272: Add regression test

Author: joroKr21

test/files/pos/t10272.scala

@@ -0,0 +1,14 @@
+object Test {
+  sealed trait AbstractProven {
+    type Proven[+A, TypeClass[_]] <: A
+  }
+
+  val abstractProven: AbstractProven = new AbstractProven {
+    override type Proven[+A, TypeClass[_]] = A
+  }
+
+  import abstractProven._
+  def x(a: Any Proven Ordering): Unit = a match {
+    case i: Int =>
+  }
+}