Doesn't work on IE 11 about aem-spa-project-archetype

[pfauchere]

Hi @adobe/cq-react-editable-components may be a bottleneck - as it may also have to be built to support ie11

[Themikeross]

We extended the support within package.json:

"browserslist": {
    "production": [
      ">0.2%",
      **"ie 9",
      "ie 11",**
      "not op_mini all"
    ],
    "development": [
      "last 1 chrome version",
      "last 1 firefox version",
      "last 1 safari version",
      "ie 9",
      "ie 11"
    ]
  }

Also added the following polyfills in index.js

import 'custom-event-polyfill';
import "core-js/es6";
import "regenerator-runtime/runtime";
import 'react-app-polyfill/ie9';
import 'react-app-polyfill/ie11';
import 'react-app-polyfill/stable';