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

compiler/testData/diagnostics/tests/smartCasts/varnotnull/varChangedInLoop.fir.kt

@@ -0,0 +1,9 @@
+public fun foo() {
+    var i: Int? = 1
+    if (i != null) {
+        while (i != 10) {
+            i++      // Here smart cast should not be performed due to a successor
+            i = null
+        }
+    }
+}