How do I make Angular 8 compatible with IE11?

Question

I upgraded to Angular 8 using ng update. It ran its migration scripts which (among other things) removed the es6/es7 imports in polyfills.ts. From

Answer 1

If you want ng serve to build the app for "es5" by default.

angular.json

"architect": {
  "build": {
    ...
    "configurations": {
      "development": {
        "tsConfig": "tsconfig-es5.app.json"
      },
      ...
    }
  },
  "serve": {
    ...
    "options": {
      "browserTarget": "bludesk-web:build:development"
    },
    ...
  }

browserlist

...
IE 11
not IE 9-10

tsconfig-es5.app.json

{
  "extends": "./tsconfig.app.json",
  "compilerOptions": {
      "target": "es5"
  }
}