Removes the `classlist.js` and `web-animations-js` polyfills from any polyfills files in a workspace. Specifically, it looks for `import 'classlist.js';` and `import 'web-animations-js';`, then removes those them along with any preceeding comments (aside from the file overview and browser polyfills header comment).
Previous versions of `ng new` generated a polyfills file with commented out imports for both modules, to avoid including them by default while giving users an easy way to enable them. This migration also looks for these commented out imports and removes them along with associated descriptive comments. This has no effect on the application, but cleans up unnecessary noise from the polyfills file.
BREAKING CHANGE:
`classlist.js` and `web-animations-js` are removed from application polyfills and uninstalled from the package. These were only needed for compatibility with Internet Explorer, which is no longer needed now that Angular only supports evergreen browsers. See: https://angular.io/guide/browser-support.
Add the following to the polyfills file for an app to re-add these packages:
```typescript
import 'classlist.js';
import 'web-animations-js';
```
And then run:
```sh
npm install classlist.js web-animations-js --save
```
