Unprefix usage of -webkit-transform in tests

LayoutTests/compositing/child-layer-3d-sorting.html

Index: LayoutTests/compositing/child-layer-3d-sorting.html
diff --git a/LayoutTests/compositing/child-layer-3d-sorting.html b/LayoutTests/compositing/child-layer-3d-sorting.html
index 04e4a3756abecff1e69c440f7bbe13af1a80fe9b..39a0b1701d83f71c1fb14cc8197a107e0ac4c162 100644
--- a/LayoutTests/compositing/child-layer-3d-sorting.html
+++ b/LayoutTests/compositing/child-layer-3d-sorting.html
@@ -6,18 +6,18 @@
 <style type="text/css" media="screen">
     #parent {
         -webkit-transform-style: preserve-3d;
-        -webkit-transform: translateZ(0);
+        transform: translateZ(0);
     }
     #child {
         width: 200px;
         height: 200px;
-        -webkit-transform: translateZ(0px);
+        transform: translateZ(0px);
         background: blue;
     }
     #child > div {
         width: 100px;
         height: 100px;
-        -webkit-transform: translateZ(0px);
+        transform: translateZ(0px);
         background: green;
     }
 </style>