Add a test to reveal flaw in call delegation with default implementations in interfaces.

compiler/testData/codegen/box/jvm8/defaults/compatibility/defaultArgsViaAnonymousObject.kt

@@ -0,0 +1,16 @@
+// !JVM_DEFAULT_MODE: compatibility
+// TARGET_BACKEND: JVM
+// JVM_TARGET: 1.8
+// WITH_RUNTIME
+
+interface A {
+    @JvmDefault
+    fun foo(x: String = "OK"): String {
+        return x
+    }
+}
+
+fun box(): String {
+    val x = object : A {}
+    return x.foo()
+}