Unprefix flexbox properties in various CSS files

Source/core/css/themeChromiumAndroid.css

 /*
  * Copyright (C) 2012 Google Inc. All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions are
  * met:
  *
  *     * Redistributions of source code must retain the above copyright
  * notice, this list of conditions and the following disclaimer.
  *     * Redistributions in binary form must reproduce the above
@@ skipping 16 matching lines @@
  * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
  * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  */
 
 /* These styles override other user-agent styles for Chromium on Android. */
 
 select[size],
 select[multiple],
 select[size][multiple] {
     -webkit-appearance: menulist;
-    -webkit-align-items: center;
+    align-items: center;
     border: 1px solid;
     border-radius: initial;
     white-space: pre;
 }