address review: update test case

Author: liufengyun

tests/patmat/3144b.check

@@ -1,2 +1,2 @@
-5: Unchecked Type Pattern
-4: Match case Unreachable
+4: Unchecked Type Pattern
+10: Unchecked Type Pattern

tests/patmat/3144b.scala

@@ -1,6 +1,11 @@
 class Test {
   def f(x: Any): Int = x match {
     case xs: List[Int] @unchecked => xs.head
+    case xs: Array[List[Int]] => 3
+    case _ => 0
+  }
+
+  def g(x: Any): Int = x match {
     case xs: List[Int @unchecked] => xs.head
     case xs: Array[List[Int]] => 3
     case _ => 0