Reduce webkit CSS prefixes in ui/ styles

ui/accessibility/extensions/alt/hide-images.css

 /* Copyright (c) 2014 The Chromium Authors. All rights reserved.
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file. */
 
 body[show-alt] img {
     /* add some fake content to hang the ::before element off */
     content: "" !important;
     background-image: url('data:image/gif;base64,R0lGODlhAQABAIAAAAAAAP///yH5BAEAAAAALAAAAAABAAEAAAIBRAA7')
 
     /* display non-floated and remove any background color */
     float: none !important;
     background-color: inherit !important;
 
     /* set height to contain the text content */
     height: 100% !important;
 }
 
 body[show-alt] img:not([alt]):not([aria-hidden=true]):not([role=presentation]):before {
     content: url('chrome-extension://__MSG_@@extension_id__/images/speech-missing-alt-16.png') " " attr(_repaired) !important;
     box-shadow: inset 0 -4px 0 rgba(230, 124, 115, 1) !important;
 }
 
 body[show-alt] img:not([aria-hidden=true]):not([role=presentation]):not([alt='']):before {
     content: url('chrome-extension://__MSG_@@extension_id__/images/speech-16.png') " " attr(alt) !important;
     box-shadow: inset 0 -4px 0 rgba(139, 195, 74, 1) !important;
     display: table;
     clear: both;
 }
 
-@-webkit-keyframes slideDown {
+@keyframes slideDown {
     from {
       transform: translateY(-150%);
     }
     to {
       transform: translateY(0px);
     }
 }
 
-@-webkit-keyframes slideUp {
+@keyframes slideUp {
     from {
       transform: translateY(0%);
     }
     to {
       transform: translateY(-150%);
     }
 }
 
 body[show-alt] .show-alt-infobar {
-    -webkit-animation-name: slideDown;
-    -webkit-animation-duration: 0.5s;
-    -webkit-animation-delay: 0.5s;
-    -webkit-animation-iteration-count: 1;
-    -webkit-animation-timing-function: ease;
-    -webkit-animation-direction: forwards;
+    animation-delay: 0.5s;
+    animation-direction: forwards;
+    animation-duration: 0.5s;
+    animation-iteration-count: 1;
+    animation-name: slideDown;
+    animation-timing-function: ease;
     transform: translateY(0%);
 }
 
 body:not([show-alt]) .show-alt-infobar {
-    -webkit-animation-name: slideUp;
-    -webkit-animation-duration: 0.5s;
-    -webkit-animation-delay: 0.5s;
-    -webkit-animation-iteration-count: 1;
-    -webkit-animation-timing-function: ease;
-    -webkit-animation-direction: forwards;
+    animation-delay: 0.5s;
+    animation-direction: forwards;
+    animation-duration: 0.5s;
+    animation-iteration-count: 1;
+    animation-name: slideUp;
+    animation-timing-function: ease;
     transform: translateY(-150%);
 }
 
 .show-alt-infobar {
+    animation-fill-mode: backwards;
     top: 0;
     left: 0;
     right: 0;
     z-index: 100000001;  /* :( */
     position: fixed !important;
     background: #fde073 !important;
     text-align: center !important;
     line-height: 2.0;
     overflow: hidden;
     box-shadow: 0 0 5px black;
-    box-shadow:         0 0 5px black;
     font-family: Arial, sans-serif !important;
     font-size: 12pt !important;
-    -webkit-animation-fill-mode: backwards;
 }
 
 .show-alt-infobar .content {
     display: inline-block !important;
 }
 
 .show-alt-infobar span {
     margin: 5px;
 }
 
@@ skipping 44 matching lines @@
     box-shadow: none !important;
     text-transform: none !important;
     padding: none !important;
     width: 13px !important;
     height: 13px !important;
     background-position: -175px -96px !important;
     background-image: url('chrome-extension://__MSG_@@extension_id__/images/statusbarButtonGlyphs.png') !important;
     background-size: 320px 144px !important;
     display: inline-block !important;
 }