style: Introduce Chrome UI privilege for parsers

The motivation is that Chrome XBL stylesheets can be parsed under author
level, but we allow some event-state pseudo classes like
:-moz-handled-clicktoplay to be used.

Also synchronize the privilege of pseudo classes in
non_ts_pseudo_class_list.rs and nsCSSPseudoClassList.h (except :fullscreen).

MozReview-Commit-ID: 8fUjjC8hbQO

components/url/lib.rs

@@ -85,6 +85,10 @@ impl ServoUrl {
         scheme == "https" || scheme == "wss"
     }
 
+    pub fn is_chrome(&self) -> bool {
+        self.scheme() == "chrome"
+    }
+
     pub fn as_str(&self) -> &str {
         self.0.as_str()
     }