Move JVM8 box test to common

compiler/testData/codegen/box/jvm8/kt14243.kt

@@ -0,0 +1,21 @@
+// TARGET_BACKEND: JVM
+// JVM_TARGET: 1.8
+
+interface Z<T> {
+    fun test(p: T): T {
+        return p
+    }
+}
+
+open class ZImpl : Z<String>
+
+class ZImpl2 : ZImpl() {
+
+    override fun test(p: String): String {
+        return super.test(p)
+    }
+}
+
+fun box(): String {
+    return ZImpl2().test("OK")
+}