JS: move RTTI tests to proper location

js/js.translator/testData/box/rtti/onNativeObject.kt

@@ -0,0 +1,18 @@
+package foo
+
+class C
+interface I
+
+fun box(): String {
+    val obj: Any = js("({})")
+
+    if (obj is C) return "obj is C"
+    if (obj is I) return "obj is I"
+
+    val obj2: Any = js("Object.create(null)")
+
+    if (obj2 is C) return "obj2 is C"
+    if (obj2 is I) return "obj2 is I"
+
+    return "OK"
+}