Add new lines at the end of fixture files

Author: Ernest Nowacki

test/fixtures/es6-export.js

@@ -4,4 +4,4 @@ export function exportTest() {
 
 export default function exportTestDefault() {
   return gettext('Hi from an ES6 export default!');
-}
+}

test/fixtures/es6-import.js

@@ -2,4 +2,4 @@ import exportTestDefault, { exportTest } from './es6-export';
 
 const fromDefaultExport = exportTestDefault(); // should be ignored
 const fromExport = exportTest(); // should be ignored
-gettext('Hi from ES6 file with import!');
+gettext('Hi from ES6 file with import!');