Fixed #2202: Add regression test.

Fixed in #2342.

Author: nicolasstucki

tests/neg/i2202.scala

@@ -0,0 +1,12 @@
+
+class A {
+  def compareTo(o: Any): Int = 0
+}
+class B extends A with Comparable[B] { // error
+  def compareTo(b: B): Int = 0
+}
+object C {
+  def main(args: Array[String]): Unit = {
+    println(new B().compareTo(new Object()))
+  }
+}