Update vendor prefixes for transition property

Since we let Autoprefixer handler prefixes in core we have to add the non-prefixed version too. With our browser settings -moz prefixed version isn't needed, so we can remove it.
Merge pull request #19 from ocean90/patch-1

Update vendor prefixes for transition property
Updating to latest dashicons files. Adds new widget icons.

Props @marestad for the new icons and @empireoflight for recompiling
the font.
Added new dashicons

481: clipboard; 482: microphone; 483: universal access; 484: name tag;
485: plugin w/checkmark; 486 WordCamp tix; 487 WordCamp sponsors; 488:
WordCamp speakers; 489: WordCamp sessions. Adjusted 177: eye to be less
“creepy”
Added new glyphs

unif490:media video, unif491 media text, unif492 audio playlist,
unif493 video playlist, unif494 better code icon, unif495 media
spreadsheet, unif496 media interactive, unif497 media document, unif498
media default, unif499 media code, unif500 media audio, unif501 media
archive
Added unif502 circle plus, unif503 randomize

props @melchoyce, @empireoflight
Adding new icon classes

482: .dashicons-microphone
483: .dashicons-universal-access
486: .dashicons-tickets
484: .dashicons-nametag
481: .dashicons-organizer
487: .dashicons-sponsor
488: .dashicons-speaker
489: .dashicons-sessions
501: .dashicons-media-archive
500: .dashicons-media-audio
499: .dashicons-media-code
498: .dashicons-media-default
497: .dashicons-media-document
496: .dashicons-media-interactive
495: .dashicons-media-spreadsheet
491: .dashicons-media-text
490: .dashicons-media-video
492: .dashicons-playlist-audio
493: .dashicons-playlist-video
502: .dashicons-plus-alt
503: .dashicons-randomize
Updating .dashicons class to match core
Updated arrows, added new code icon (unif505), added move (unif504), opposite-of-distraction-free (unif506), props @melchoyce, @empireoflight
Replaced old code icon (unif475)
Accessibility icon updated

unif483 no longer has the circle around it. In case we need it again, I
copied it to unif507
Adding new dashicons classes

.dashicons-editor-contract, .dashicons-external,
.dashicons-accessibility-alt
Update dashicons.css for class name changes, see https://core.trac.wordpress.org/ticket/26936#comment:60
Fix CSS class names, see 308574f
Remove HTML comments for 3.9 icons