[K/N] Convert and enable some tests using System.out?.println()

^KT-59057

Merge-request: KT-MR-10546
Merged-by: Vladimir Sukharev <Vladimir.Sukharev@jetbrains.com>

compiler/testData/codegen/box/classes/kt707.kt

@@ -1,15 +1,8 @@
-// IGNORE_BACKEND: WASM
-// WASM_MUTE_REASON: IGNORED_IN_JS
-// IGNORE_BACKEND: JS_IR
-// IGNORE_BACKEND: JS_IR_ES6
-// TODO: Enable for JS when it supports Java class library.
-// IGNORE_BACKEND: JS, NATIVE
 class List<T>(val head: T, val tail: List<T>? = null)
 
 fun <T> List<T>.mapHead(f: (T)-> T): List<T> = List<T>(f(head), null)
 
 fun box() : String {
   val a: Int = List<Int>(1).mapHead{it * 2}.head
-  System.out?.println(a)
-  return "OK"
+  return if (a == 2) "OK" else a.toString()
 }