JS backend: fixed accessing to native enum entries.

js/js.translator/testData/enum/cases/nativeEnum.js

@@ -0,0 +1,5 @@
+var JsEnum = {
+    Foo : 1,
+    Bar : "BAR",
+    Baz : { ok : "OK" }
+};

js/js.translator/testData/enum/cases/nativeEnum.kt

@@ -0,0 +1,19 @@
+package foo
+
+native
+enum class JsEnum {
+    Foo
+    Bar
+    Baz
+}
+
+// TODO uncomment when KT-5605 will be fixed
+// fun JsEnum.extImplicit() = Foo
+
+fun box(): String {
+    assertEquals(1, JsEnum.Foo)
+    assertEquals("BAR", JsEnum.Bar)
+    assertEquals("OK", (JsEnum.Baz: dynamic).ok)
+
+    return "OK"
+}