Remove checks for matchMedia

All es6 modules supporting browsers support window.matchMedia
https://caniuse.com/matchmedia

src/javascripts/components/navigation.mjs

@@ -115,18 +115,16 @@ class Navigation {
  }
 
  init () {
- if ('matchMedia' in window) {
- // Set the matchMedia to the govuk-frontend tablet breakpoint
- this.mql = window.matchMedia('(min-width: 40.0625em)')
-
- if ('addEventListener' in this.mql) {
- this.mql.addEventListener('change', () => this.setHiddenStates())
- } else {
- // addListener is a deprecated function, however addEventListener
- // isn't supported by Safari < 14. We therefore add this in as
- // a fallback for those browsers
- this.mql.addListener(() => this.setHiddenStates())
- }
+ // Set the matchMedia to the govuk-frontend tablet breakpoint
+ this.mql = window.matchMedia('(min-width: 40.0625em)')
+
+ // MediaQueryList.addEventListener isn't supported by Safari < 14 so we need
+ // to be able to fall back to the deprecated MediaQueryList.addListener
+ if ('addEventListener' in this.mql) {
+ this.mql.addEventListener('change', () => this.setHiddenStates())
+ } else {
+ // @ts-expect-error Property 'addListener' does not exist
+ this.mql.addListener(() => this.setHiddenStates())
  }
 
  this.setHiddenStates()