- Add role=dialog and an aria-labelledby attribute to the modal container.
- Change the modal title to h1.
- Remove one ` ` that gets read out as `blank` by screen readers.
- Replace the Cancel link with a button.
- Clean up unused CSS.
Props afercia.
Fixes#30468.
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git-svn-id: http://core.svn.wordpress.org/trunk@36958 1a063a9b-81f0-0310-95a4-ce76da25c4cd
