Remove webkit prefixes for transform and perspective in ui/ styles

ui/webui/resources/images/throbber_medium.svg

 <!-- This version of the throbber is good for size 28x28dp or more. -->
 <svg version="1" xmlns="http://www.w3.org/2000/svg"
                  xmlns:xlink="http://www.w3.org/1999/xlink"
      viewBox="0 0 28 28">
   <!-- 28= RADIUS*2 + STROKEWIDTH -->
 
   <title>Material design circular activity spinner with CSS3 animation</title>
   <style type="text/css">
       /**************************/
       /* STYLES FOR THE SPINNER */
@@ skipping 19 matching lines @@
         height:28px; /* 2*RADIUS + STROKEWIDTH */
       }
       .qp-circular-loader-path {
         stroke-dasharray: 58.9;  /* 2*RADIUS*PI * ARCSIZE/360 */
         stroke-dashoffset: 58.9; /* 2*RADIUS*PI * ARCSIZE/360 */
                                  /* hides things initially */
       }
 
       /* SVG elements seem to have a different default origin */
       .qp-circular-loader, .qp-circular-loader * {
-        -webkit-transform-origin: 50% 50%;
+        transform-origin: 50% 50%;
       }
 
       /* Rotating the whole thing */
       @-webkit-keyframes rotate {
         from {transform: rotate(0deg);}
         to {transform: rotate(360deg);}
       }
       .qp-circular-loader {
         -webkit-animation-name: rotate;
         -webkit-animation-duration: 1568.63ms; /* 360 * ARCTIME / (ARCSTARTROT + (360-ARCSIZE)) */
@@ skipping 47 matching lines @@
   <!-- 12.5= RADIUS -->
   <!-- 1.5=  STROKEWIDTH/2 -->
   <!-- ARCSIZE would affect the 1.5,14 part of this... 1.5,14 is specific to
        270 degress -->
   <g class="qp-circular-loader">
     <path class="qp-circular-loader-path" fill="none" 
           d="M 14,1.5 A 12.5,12.5 0 1 1 1.5,14" stroke-width="3"
           stroke-linecap="round"></path>
   </g>
 </svg>