JVM_IR indy-lambdas: minor updates and fixes

KT-44278 KT-26060 KT-42621

compiler/testData/codegen/box/invokedynamic/lambdas/lambdaToSting.kt

@@ -0,0 +1,14 @@
+// TARGET_BACKEND: JVM
+// IGNORE_BACKEND: JVM
+// JVM_TARGET: 1.8
+// LAMBDAS: INDY
+// WITH_RUNTIME
+
+fun lambdaToString(fn: () -> Unit) = fn.toString()
+
+fun box(): String {
+    val str = lambdaToString {}
+    if (!str.startsWith("LambdaToStingKt"))
+        return "Failed: indy lambda toString is inherited from java.lang.Object"
+    return "OK"
+}