- changes the "X" links in buttons, improves their color contrast ratio and focus style
- adds screen reader text "Remove item: + tagname"
- uses `wp.a11y.speak()` to give screen reader users feedback when adding/removing tags
- makes the `tagcloud-link` toggle a button, with an `aria-expanded` attribute to indicate the tag cloud collapsed/expanded state
- changes colors for the autocomplete highlighted option in order to have a better color contrast ratio
- reduces the font size for the autocomplete on Press This
- removes CSS related to the old `suggest.js` from Press This
Props joedolson, cgrymala, azaozz, afercia.
Fixes#27555.
Built from https://develop.svn.wordpress.org/trunk@38880
git-svn-id: http://core.svn.wordpress.org/trunk@38823 1a063a9b-81f0-0310-95a4-ce76da25c4cd