[NI] Don't forget to analyze whole block for last postponed expression

compiler/testData/diagnostics/tests/functionLiterals/functionExpressionAsLastExpressionInBlock.kt

@@ -0,0 +1,15 @@
+// !DIAGNOSTICS: -UNUSED_VARIABLE -UNUSED_EXPRESSION
+
+import java.util.HashSet
+
+fun test123() {
+    val g: (Int) -> Unit = if (true) {
+        val set = HashSet<Int>()
+        fun (i: Int) {
+            set.add(i)
+        }
+    }
+    else {
+        { it -> it }
+    }
+}