Dashicons: Update to the latest dashicons files.

New icons:
* .dashicons-calendar-alt (f508)
* .dashicons-carrot (f511)
* .dashicons-grid-view (f509)
* .dashicons-index-card (f510)

props liljimmi, melchoyce, empireoflight.
see #27844.
Built from https://develop.svn.wordpress.org/trunk@29520


git-svn-id: http://core.svn.wordpress.org/trunk@29296 1a063a9b-81f0-0310-95a4-ce76da25c4cd