Auto merge of #2158 - Turbo87:eslint, r=locks

ESLint: Use `babel-eslint` parser to allow decorators and field initialization

This is needed to convert the `app/router.js` file to an ES6 class (see #2149 (comment)), and now the default in Ember.js apps (see https://github.com/ember-cli/ember-new-output/blob/v3.15.2/.eslintrc.js).

r? @locks

Author: bors

.eslintrc.js

@@ -1,8 +1,12 @@
 module.exports = {
   root: true,
+  parser: 'babel-eslint',
   parserOptions: {
     ecmaVersion: 2018,
     sourceType: 'module',
+    ecmaFeatures: {
+      legacyDecorators: true,
+    },
   },
   plugins: ['ember', 'prettier'],
   extends: ['eslint:recommended', 'plugin:ember/recommended', 'plugin:prettier/recommended'],

package-lock.json

@@ -31,6 +31,7 @@
   "devDependencies": {
     "@ember/jquery": "^1.1.0",
     "@ember/optional-features": "^1.3.0",
+    "babel-eslint": "^10.0.3",
     "babel-plugin-transform-object-rest-spread": "^6.26.0",
     "broccoli-asset-rev": "^3.0.0",
     "ember-a11y-testing": "^2.0.0",