Unprefix usage of -webkit-transform in tests

LayoutTests/css3/filters/effect-reference-hw.html

 <svg xmlns="http://www.w3.org/2000/svg" width="0" height="0" version="1.1">
   <defs>
     <filter id="colormatrix" color-interpolation-filters="sRGB">
       <feColorMatrix type="hueRotate" values="180"/>
     </filter>
     <filter id="morphology" color-interpolation-filters="sRGB">
       <feMorphology radius="10" operator="dilate"/>
     </filter>
     <filter id="componenttransfer" color-interpolation-filters="sRGB">
       <feComponentTransfer>
@@ skipping 49 matching lines @@
       <feTile x="0" y="0" width="160" height="80"/>
     </filter>
     <filter id="drop-shadow" color-interpolation-filters="sRGB">
       <feDropShadow dx="10" dy="5" stdDeviation="4"/>
     </filter>
   </defs>
 </svg>
 <style>
 img {
     margin: 10px;
-    -webkit-transform: translateZ(0);
+    transform: translateZ(0);
 }
 </style>
 <img src="resources/reference.png">
 <img style="-webkit-filter: url(#colormatrix); filter: url(#colormatrix);" src="resources/reference.png">
 <img style="-webkit-filter: url(#morphology); filter: url(#morphology);" src="resources/reference.png">
 <img style="-webkit-filter: url(#componenttransfer); filter: url(#componenttransfer);" src="resources/reference.png">
 <img style="-webkit-filter: url(#blurY); filter: url(#blurY);" src="resources/reference.png">
 <img style="-webkit-filter: url(#blend); filter: url(#blend);" src="resources/reference.png">
 <img style="-webkit-filter: url(#lighting); filter: url(#lighting);" src="resources/reference.png">
 <img style="-webkit-filter: url(#offset); filter: url(#offset);" src="resources/reference.png">
 <img style="-webkit-filter: url(#convolvematrix); filter: url(#convolvematrix);" src="resources/reference.png">
 <img style="-webkit-filter: url(#displacement); filter: url(#displacement);" src="resources/reference.png">
 <img style="-webkit-filter: url(#merge); filter: url(#merge);" src="resources/reference.png">
 <img style="-webkit-filter: url(#flood); filter: url(#flood);" src="resources/reference.png">
 <img style="-webkit-filter: url(#turbulence); filter: url(#turbulence);" src="resources/reference.png">
 <img style="-webkit-filter: url(#tile); filter: url(#tile);" src="resources/reference.png">
 <img style="-webkit-filter: url(#drop-shadow); filter: url(#drop-shadow);" src="resources/reference.png">