Remove support for IE11 and dead browsers

Handlebars v5 will target modern browsers,
while older browsers will still receive support
via version 4.x.

tests/integration/multi-nodejs-test/.eslintrc.js

@@ -1,5 +1,5 @@
 module.exports = {
-  extends: ['eslint:recommended', 'plugin:es5/no-es2015', 'prettier'],
+  extends: ['eslint:recommended', 'prettier'],
   globals: {
     self: false
   },