style: Support matching :-moz-browser-frame and :-moz-table-border-nonzero against snapshots.

components/style/gecko/selector_parser.rs

@@ -206,6 +206,14 @@ impl NonTSPseudoClass {
         }
         apply_non_ts_list!(pseudo_class_geckotype)
     }
+
+    /// Returns true if the evaluation of the pseudo-class depends on the
+    /// element's attributes.
+    pub fn is_attr_based(&self) -> bool {
+        matches!(*self,
+                 NonTSPseudoClass::MozTableBorderNonzero |
+                 NonTSPseudoClass::MozBrowserFrame)
+    }
 }
 
 /// The dummy struct we use to implement our selector parsing.

components/style/gecko/snapshot.rs

@@ -55,6 +55,13 @@ impl GeckoElementSnapshot {
         self
     }
 
+    /// Returns true if the snapshot has stored state for pseudo-classes
+    /// that depend on things other than `ElementState`.
+    #[inline]
+    pub fn has_other_pseudo_class_state(&self) -> bool {
+        self.has_any(Flags::OtherPseudoClassState)
+    }
+
     /// selectors::Element::attr_matches
     pub fn attr_matches(&self,
                         ns: &NamespaceConstraint<&Namespace>,