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

compiler/testData/diagnostics/tests/controlFlowAnalysis/kt1191.fir.kt

@@ -0,0 +1,21 @@
+//KT-1191 Wrong detection of unused parameters
+package kt1191
+
+interface FunctionalList<T> {
+    val size: Int
+    val head: T
+    val tail: FunctionalList<T>
+}
+
+fun <T> FunctionalList<T>.plus(element: T) : FunctionalList<T> = object: FunctionalList<T> {
+    override val size: Int
+    get() = 1 + this@plus.size
+    override val tail: FunctionalList<T>
+    get() = this@plus
+    override val head: T
+    get() = element
+}
+
+fun foo(unused: Int) = object {
+    val a : Int get() = unused
+}