Add classList polyfill for IE classList.toggle('foo', force)

What does this MR do?

EE MR, https://gitlab.com/gitlab-org/gitlab-ee/merge_requests/3527

• Add classList polyfill for IE, classList.toggle('foo', force)

Are there points in the code the reviewer needs to double check?

Requirements

• Supports second parameter force in the toggle method, classList.toggle('foo', true), see https://developer.mozilla.org/en-US/docs/Web/API/Element/classList#Methods
• Works with SVGs (classList doesn't work at all with SVGs in IE natively)
• Lightweight
• Available on npm (nice to have)

Options

• classlist-polyfill
  • Available on npm, https://www.npmjs.com/package/classlist-polyfill
  • Has tests
  • No extra sub-dependency bloat (5.56kb)
  • Works with SVGs
  • Fork from eligrey/classList.js but planned to be deprecated now that the upstream has new maintainers
• eligrey/classList.js
  • Not available on npm (manual dependency management) ❌
  • Has tests
  • No extra sub-dependency bloat
  • Does not work with SVGs ❌
• remy/polyfills/classList.js
  • Not available on npm (manual dependency management) ❌
  • No tests ❌
  • No extra sub-dependency bloat
  • Does not work with SVGs ❌
• devongovett minimal gist
  • Not available on npm (manual dependency management) ❌
  • No tests ❌
  • No extra sub-dependency bloat
  • Does not work with SVGs ❌

Also see https://github.com/Modernizr/Modernizr/wiki/HTML5-Cross-Browser-Polyfills#classlist

Why was this MR needed?

IE 11 does not support force parameter in classList.toggle('foo', force).

We have existing code that just doesn't work correctly and future code,

• https://gitlab.com/gitlab-org/gitlab-ce/blob/50a5d638e56443ffc7d4d08b3706b9c63e372dfa/app/assets/javascripts/label_manager.js#L46
• https://gitlab.com/gitlab-org/gitlab-ce/blob/50a5d638e56443ffc7d4d08b3706b9c63e372dfa/app/assets/javascripts/landing.js#L14

Does this MR meet the acceptance criteria?

• Changelog entry added, if necessary
• Tests added for this feature/bug
• Review
  • Has been reviewed by Frontend
• Conform by the merge request performance guides
• Conform by the style guides
• Squashed related commits together
• Internationalization required/considered

What are the relevant issue numbers?

Closes #38916 (closed)