Add PolyType to Infer#normalize.

It arises when inferring the type of an overloaded call:

  def g(s: String): String = s
  def f: String = ???
  def f[C](c: C): String = g(f)

Also refined warning when isHKSubType is called with
arguments which very likely were never meant to be compared.

1 files changed, 13 insertions, 0 deletions

diff --git a/test/files/pos/kinds.scala b/test/files/pos/kinds.scala
new file mode 100644
index 0000000000..6d6da0c8b6
--- /dev/null
+++ b/test/files/pos/kinds.scala
@@ -0,0 +1,13 @@
+trait IllKind1 {
+  def g(s: String): String = s
+  def f: String = ???
+  def f[C](c: C): String = g(f)
+}
+
+trait IllKind2 {
+  def b1: Char = ???
+  def b2: Byte = ???
+
+  def f1 = "abc" contains b1
+  def f2 = "abc" contains b2
+}