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/style/stylesheets/mod.rs

@@ -70,6 +70,11 @@ impl UrlExtraData {
         // TODO
         "(stylo: not supported)"
     }
+
+    /// True if this URL scheme is chrome.
+    pub fn is_chrome(&self) -> bool {
+        self.mIsChrome
+    }
 }
 
 // XXX We probably need to figure out whether we should mark Eq here.