add flattener test skeleton

apps/remix-ide-e2e/src/tests/contract_flattener.test.ts

@@ -0,0 +1,9 @@
+'use strict'
+import { NightwatchBrowser } from 'nightwatch'
+import init from '../helpers/init'
+
+module.exports = {
+  before: function (browser: NightwatchBrowser, done: VoidFunction) {
+    init(browser, done)
+  }
+}