[FIR-TEST] Add new testdata generated after changes in previous commit

compiler/testData/diagnostics/tests/nullabilityAndSmartCasts/kt2234.fir.kt

@@ -0,0 +1,23 @@
+// !CHECK_TYPE
+
+package a
+
+//KT-2234 'period!!' has type Int?
+
+class Pair<A, B>(val a: A, val b: B)
+
+fun main() {
+    val d : Long = 1
+    val period : Int? = null
+    if (period != null) Pair(d, checkSubtype<Int>(period!!)) else Pair(d, 1)
+    if (period != null) Pair(d, checkSubtype<Int>(period)) else Pair(d, 1)
+}
+
+fun foo() {
+    val x : Int? = 3
+    if (x != null)  {
+        val u = checkSubtype<Int>(x!!)
+        val y = checkSubtype<Int>(x)
+        val z : Int = y
+    }
+}