Add vanilla to test suite

Author: Ives van Hoorne

packages/app/integration-tests/tests/__image_snapshots__/vanilla-snap.png

@@ -25,10 +25,10 @@ const SANDBOXES = [
   'github/cssinjs/egghead/tree/master/from-sass-to-cssinjs/templates-and-variables', // postcss egghead
   'xp5qy8r93q', // babel example
   'angular', // angular template
-
   // Sass importing
   '2ppkvzx570', // nested imports
   'rl2m3xklyo', // node_modules import
+  'vanilla',
 ];
 
 function pageLoaded(page) {