Bug 1695565 - Fix appearance-cssom-001.html. r=boris

* Remove some legacy appearance aliases that other engines don't
   implement.

 * Allow to pass with unimplemented <compat-auto> values, since per the
   spec the idea of these is to get them removed, see
   w3c/csswg-drafts#8506 for the ones we don't
   implement.

 * Also allow the `-moz-` prefix to be implemented, because we can't
   quite get rid of it (people use it to remove the <input type=number>
   buttons with -moz-appearance: textfield and so on), and the
   alternative is to implement a bunch of non-standard ::-webkit-
   pseudo-elements.

Differential Revision: https://phabricator.services.mozilla.com/D171243

servo/components/style/values/specified/box.rs

@@ -1726,7 +1726,6 @@ pub enum Appearance {
     /// A searchfield.
     Searchfield,
     /// A multi-line text field, e.g. HTML <textarea>.
-    #[parse(aliases = "textfield-multiline")]
     Textarea,
     /// A checkbox element.
     Checkbox,
@@ -1737,10 +1736,8 @@ pub enum Appearance {
     /// List boxes.
     Listbox,
     /// A horizontal meter bar.
-    #[parse(aliases = "meterbar")]
     Meter,
     /// A horizontal progress bar.
-    #[parse(aliases = "progressbar")]
     ProgressBar,
     /// A typical dialog button.
     Button,