JS: move RTTI tests to proper location

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

@@ -0,0 +1,21 @@
+package foo
+
+
+open class A
+
+interface B
+
+class C : A(), B
+
+fun box(): String {
+
+    val a = A()
+    val b = object : B {
+    }
+    val c = C()
+
+    if (a is B) return "a is B"
+    if (b !is B) return "b !is B"
+    if (c !is B) return "c !is B"
+    return "OK"
+}