In the example apps used in the `ngUpgrade` guide, the AngularJS files
are loaded in `index.html` from `https://code.angularjs.org/`. Latest
browsers prevent loading the scripts from a page running on localhost
due to CORS:
```
Access to script at 'https://code.angularjs.org/1.5.5/angular.js' from origin
'http://localhost:9876' has been blocked by CORS policy: No 'Access-Control-Allow-Origin'
header is present on the requested resource.
```
NOTE:
Loading the files from `code.angularjs.org` is not mentioned in the
guide, therefore it is not needed to mention this config change there.
PR Close#36015