Test for inference ticket (#8544)

Test for inference ticket

test/files/pos/t1479.scala

@@ -0,0 +1,32 @@
+class A {
+  class C
+  class Inf[X<:C](x: X) 
+  def f[X<:C](x: X) = ()
+}
+
+object Test extends A {
+  val c: C = new C
+  f(c)
+  new Inf(c)
+}
+
+/*
+snips $ ~/scala-2.13.0-M2/bin/scalac -d /tmp t1479.scala 
+t1479.scala:10: error: inferred type arguments [Test.C] do not conform to class Inf's type parameter bounds [X <: A.this.C]
+  new Inf(c)
+  ^
+t1479.scala:10: error: type mismatch;
+ found   : Test.C
+ required: X
+  new Inf(c)
+          ^
+two errors found
+snips $ ~/scala-2.13.0-M3/bin/scalac -d /tmp t1479.scala 
+t1479.scala:10: error: type mismatch;
+ found   : Test.C
+ required: A.this.C
+  new Inf(c)
+          ^
+one error found
+snips $ ~/scala-2.13.0-M5/bin/scalac -d /tmp t1479.scala 
+*/