FIR2IR: create local classes on the fly properly

compiler/testData/ir/irText/firProblems/FlushFromAnonymous.kt

@@ -0,0 +1,21 @@
+// SKIP_KLIB_TEST
+// FILE: Collector.java
+
+public class Collector {
+    public void flush() {}
+}
+
+// FILE: FlushFromAnonymous.kt
+
+class Serializer() {
+    fun serialize() {
+        val messageCollector = createMessageCollector()
+        try {
+
+        } catch (e: Throwable) {
+            messageCollector.flush()
+        }
+    }
+
+    private fun createMessageCollector() = object : Collector() {}
+}