JS: create new common directory for all generated tests, migrate several tests there

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

@@ -0,0 +1,22 @@
+package foo
+
+class A {
+    val a = 3
+    companion object {
+        val a = 2
+        val b = 5
+    }
+}
+
+
+fun box(): String {
+    if (A.a != 2) return "A.a != 2, it: ${A.a}"
+    if (A.b != 5) return "A.b != 5, it: ${A.b}"
+
+    val b = A
+    if (b.a != 2) return "b = A; b != 2, it: ${b.a}"
+
+    if (A().a != 3) return "A().a != 3, it: ${A().a}"
+
+    return "OK"
+}