Update eslint.js

not sure why 'latest' is not working, but this fixes the annoying errors related to es5 being default

Author: lly-c232733

libraries/codemirror/eslint.js

@@ -46,7 +46,7 @@
         const errors = new eslint().verify(text, {
             root: true,
             parserOptions: {
-                ecmaVersion: "latest"
+                ecmaVersion: "2019"
             },
             extends: ['eslint:recommended', 'airbnb-base'],
             env: {