FIR2IR: create local classes on the fly properly

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

@@ -0,0 +1,33 @@
+class Serializer {
+  constructor() /* primary */ {
+    super/*Any*/()
+    /* <init>() */
+
+  }
+
+  fun serialize() {
+    val messageCollector: <no name provided> = <this>.createMessageCollector()
+    try { // BLOCK
+    }
+    catch (e: Throwable){ // BLOCK
+      messageCollector.flush()
+    }
+
+  }
+
+  private fun createMessageCollector(): <no name provided> {
+    return { // BLOCK
+      local class <no name provided> : Collector {
+        constructor() /* primary */ {
+          super/*Collector*/()
+          /* <init>() */
+
+        }
+
+      }
+
+      <no name provided>()
+    }
+  }
+
+}