JS: move more test to box tests

js/js.translator/testData/box/native/classObject.kt

@@ -0,0 +1,18 @@
+package foo
+
+@native
+class A(val c: Int) {
+    @native
+    companion object {
+        val g: Int = noImpl
+        val c: String = noImpl
+    }
+}
+
+fun box(): String {
+    if (A.g != 3) return "fail1"
+    if (A.c != "hoooray") return "fail2"
+    if (A(2).c != 2) return "fail3"
+
+    return "OK"
+}