reinstates babel polyfill inclusion for js sources. adds allowJs flag

wherehows-web/ember-cli-build.js

@@ -6,6 +6,10 @@ const MergeTrees = require('broccoli-merge-trees');
 
 module.exports = function(defaults) {
   const app = new EmberApp(defaults, {
+    'ember-cli-babel': {
+      includePolyfill: true
+    },
+
     storeConfigInMeta: false,
 
     SRI: {

wherehows-web/tsconfig.json

@@ -2,6 +2,7 @@
   "compilerOptions": {
     "target": "es2015",
     "moduleResolution": "node",
+    "allowJs": true,
     "noEmitOnError": true,
     "baseUrl": ".",
     "sourceMap": true,