Unprefix usage of -webkit-transform in tests

LayoutTests/compositing/backface-visibility-transformed.html

Index: LayoutTests/compositing/backface-visibility-transformed.html
diff --git a/LayoutTests/compositing/backface-visibility-transformed.html b/LayoutTests/compositing/backface-visibility-transformed.html
index a6037c434af7fb3c4c127087b60b173d88655f78..8911170ce46b61d385d4cc33d7f572d1a95f6321 100644
--- a/LayoutTests/compositing/backface-visibility-transformed.html
+++ b/LayoutTests/compositing/backface-visibility-transformed.html
@@ -7,7 +7,7 @@
     }
     .frame {
         -webkit-transform-style: preserve-3d;
-        -webkit-transform: translateX(200px) rotateY(85deg);
+        transform: translateX(200px) rotateY(85deg);
     }
     .front {
         position:absolute;
@@ -17,7 +17,7 @@
     .back {
         position:absolute;
         background-color: green;
-        -webkit-transform: rotateY(180deg);
+        transform: rotateY(180deg);
     }
     div {
       height: 200px;