Remove prefixed properties. No bug.

(Imported from https://hg.csswg.org/test/ by dbaron.)

layout/reftests/w3c-css/submitted/flexbox/flexbox-baseline-align-self-baseline-vert-001.html

@@ -28,8 +28,6 @@
     .flexContainer {
       display: inline-flex;
       flex-direction: column;
-      display: -webkit-inline-flex;
-      -webkit-flex-direction: column;
       background: lightblue;
       align-items: baseline;
     }