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

compiler/testData/diagnostics/tests/nullabilityAndSmartCasts/kt2212.fir.kt

@@ -0,0 +1,8 @@
+//KT-2212 Incomplete nullability information
+package kt2212
+
+fun main() {
+    val x: Int? = 1
+    if (x == null) return
+    System.out.println(x.plus(x!!))
+}