diff --git a/components/layout_thread/dom_wrapper.rs b/components/layout_thread/dom_wrapper.rs
index f19e5e13b78..899c47b4747 100644
--- a/components/layout_thread/dom_wrapper.rs
+++ b/components/layout_thread/dom_wrapper.rs
@@ -686,21 +686,23 @@ impl<'le> ::selectors::Element for ServoLayoutElement<'le> {
         self.element.namespace()
     }
 
-    fn match_pseudo_element(&self,
-                            _pseudo: &PseudoElement,
-                            _context: &mut MatchingContext)
-                            -> bool
-    {
+    fn match_pseudo_element(
+        &self,
+        _pseudo: &PseudoElement,
+        _context: &mut MatchingContext<Self::Impl>,
+    ) -> bool {
         false
     }
 
-    fn match_non_ts_pseudo_class<F>(&self,
-                                    pseudo_class: &NonTSPseudoClass,
-                                    _: &mut MatchingContext,
-                                    _: &RelevantLinkStatus,
-                                    _: &mut F)
-                                    -> bool
-        where F: FnMut(&Self, ElementSelectorFlags),
+    fn match_non_ts_pseudo_class<F>(
+        &self,
+        pseudo_class: &NonTSPseudoClass,
+        _: &mut MatchingContext<Self::Impl>,
+        _: &RelevantLinkStatus,
+        _: &mut F,
+    ) -> bool
+    where
+        F: FnMut(&Self, ElementSelectorFlags),
     {
         match *pseudo_class {
             // https://github.com/servo/servo/issues/8718
@@ -1176,11 +1178,11 @@ impl<'le> ::selectors::Element for ServoThreadSafeLayoutElement<'le> {
         self.element.get_namespace()
     }
 
-    fn match_pseudo_element(&self,
-                            _pseudo: &PseudoElement,
-                            _context: &mut MatchingContext)
-                            -> bool
-    {
+    fn match_pseudo_element(
+        &self,
+        _pseudo: &PseudoElement,
+        _context: &mut MatchingContext<Self::Impl>
+    ) -> bool {
         false
     }
 
@@ -1203,13 +1205,15 @@ impl<'le> ::selectors::Element for ServoThreadSafeLayoutElement<'le> {
         }
     }
 
-    fn match_non_ts_pseudo_class<F>(&self,
-                                    _: &NonTSPseudoClass,
-                                    _: &mut MatchingContext,
-                                    _: &RelevantLinkStatus,
-                                    _: &mut F)
-                                    -> bool
-        where F: FnMut(&Self, ElementSelectorFlags),
+    fn match_non_ts_pseudo_class<F>(
+        &self,
+        _: &NonTSPseudoClass,
+        _: &mut MatchingContext<Self::Impl>,
+        _: &RelevantLinkStatus,
+        _: &mut F,
+    ) -> bool
+    where
+        F: FnMut(&Self, ElementSelectorFlags),
     {
         // NB: This could maybe be implemented
         warn!("ServoThreadSafeLayoutElement::match_non_ts_pseudo_class called");
diff --git a/components/script/dom/element.rs b/components/script/dom/element.rs
index 9045918d2f8..1d8c12f9a64 100644
--- a/components/script/dom/element.rs
+++ b/components/script/dom/element.rs
@@ -2528,11 +2528,11 @@ impl<'a> SelectorsElement for DomRoot<Element> {
         self.upcast::<Node>().GetParentElement()
     }
 
-    fn match_pseudo_element(&self,
-                            _pseudo: &PseudoElement,
-                            _context: &mut MatchingContext)
-                            -> bool
-    {
+    fn match_pseudo_element(
+        &self,
+        _pseudo: &PseudoElement,
+        _context: &mut MatchingContext<Self::Impl>,
+    ) -> bool {
         false
     }
 
@@ -2594,13 +2594,15 @@ impl<'a> SelectorsElement for DomRoot<Element> {
         self.namespace()
     }
 
-    fn match_non_ts_pseudo_class<F>(&self,
-                                    pseudo_class: &NonTSPseudoClass,
-                                    _: &mut MatchingContext,
-                                    _: &RelevantLinkStatus,
-                                    _: &mut F)
-                                    -> bool
-        where F: FnMut(&Self, ElementSelectorFlags),
+    fn match_non_ts_pseudo_class<F>(
+        &self,
+        pseudo_class: &NonTSPseudoClass,
+        _: &mut MatchingContext<Self::Impl>,
+        _: &RelevantLinkStatus,
+        _: &mut F,
+    ) -> bool
+    where
+        F: FnMut(&Self, ElementSelectorFlags),
     {
         match *pseudo_class {
             // https://github.com/servo/servo/issues/8718
diff --git a/components/selectors/context.rs b/components/selectors/context.rs
index 22c886315fb..fa6d4428f56 100644
--- a/components/selectors/context.rs
+++ b/components/selectors/context.rs
@@ -5,6 +5,7 @@
 use attr::CaseSensitivity;
 use bloom::BloomFilter;
 use nth_index_cache::NthIndexCache;
+use parser::SelectorImpl;
 use tree::OpaqueElement;
 
 /// What kind of selector matching mode we should use.
@@ -74,7 +75,10 @@ impl QuirksMode {
 /// Data associated with the matching process for a element.  This context is
 /// used across many selectors for an element, so it's not appropriate for
 /// transient data that applies to only a single selector.
-pub struct MatchingContext<'a> {
+pub struct MatchingContext<'a, Impl>
+where
+    Impl: SelectorImpl,
+{
     /// Input with the matching mode we should use when matching selectors.
     pub matching_mode: MatchingMode,
     /// Input with the bloom filter used to fast-reject selectors.
@@ -107,9 +111,13 @@ pub struct MatchingContext<'a> {
 
     quirks_mode: QuirksMode,
     classes_and_ids_case_sensitivity: CaseSensitivity,
+    _impl: ::std::marker::PhantomData<Impl>,
 }
 
-impl<'a> MatchingContext<'a> {
+impl<'a, Impl> MatchingContext<'a, Impl>
+where
+    Impl: SelectorImpl,
+{
     /// Constructs a new `MatchingContext`.
     pub fn new(
         matching_mode: MatchingMode,
@@ -144,6 +152,7 @@ impl<'a> MatchingContext<'a> {
             classes_and_ids_case_sensitivity: quirks_mode.classes_and_ids_case_sensitivity(),
             scope_element: None,
             nesting_level: 0,
+            _impl: ::std::marker::PhantomData,
         }
     }
 
diff --git a/components/selectors/matching.rs b/components/selectors/matching.rs
index 596fa8afe9f..e7ae0184c47 100644
--- a/components/selectors/matching.rs
+++ b/components/selectors/matching.rs
@@ -55,15 +55,15 @@ impl ElementSelectorFlags {
 }
 
 /// Holds per-compound-selector data.
-struct LocalMatchingContext<'a, 'b: 'a> {
-    shared: &'a mut MatchingContext<'b>,
+struct LocalMatchingContext<'a, 'b: 'a, Impl: SelectorImpl> {
+    shared: &'a mut MatchingContext<'b, Impl>,
     matches_hover_and_active_quirk: bool,
 }
 
 pub fn matches_selector_list<E>(
     selector_list: &SelectorList<E::Impl>,
     element: &E,
-    context: &mut MatchingContext,
+    context: &mut MatchingContext<E::Impl>,
 ) -> bool
 where
     E: Element
@@ -141,9 +141,13 @@ impl RelevantLinkStatus {
     /// If we found the relevant link for this element, record that in the
     /// overall matching context for the element as a whole and stop looking for
     /// addtional links.
-    fn examine_potential_link<E>(&self, element: &E, context: &mut MatchingContext)
-                                 -> RelevantLinkStatus
-        where E: Element,
+    fn examine_potential_link<E>(
+        &self,
+        element: &E,
+        context: &mut MatchingContext<E::Impl>,
+    ) -> RelevantLinkStatus
+    where
+        E: Element,
     {
         // If a relevant link was previously found, we no longer want to look
         // for links.  Only the nearest ancestor link is considered relevant.
@@ -168,8 +172,13 @@ impl RelevantLinkStatus {
     /// matching.  This is true only if the element is a link, an relevant link
     /// exists for the element, and the visited handling mode is set to accept
     /// relevant links as visited.
-    pub fn is_visited<E>(&self, element: &E, context: &MatchingContext) -> bool
-        where E: Element,
+    pub fn is_visited<E>(
+        &self,
+        element: &E,
+        context: &MatchingContext<E::Impl>,
+    ) -> bool
+    where
+        E: Element,
     {
         if !element.is_link() {
             return false
@@ -193,8 +202,13 @@ impl RelevantLinkStatus {
     /// as visited.  If this is a relevant link, then is it unvisited if the
     /// visited handling mode is set to treat all links as unvisted (including
     /// relevant links).
-    pub fn is_unvisited<E>(&self, element: &E, context: &MatchingContext) -> bool
-        where E: Element,
+    pub fn is_unvisited<E>(
+        &self,
+        element: &E,
+        context: &MatchingContext<E::Impl>
+    ) -> bool
+    where
+        E: Element,
     {
         if !element.is_link() {
             return false
@@ -277,7 +291,7 @@ pub fn matches_selector<E, F>(
     offset: usize,
     hashes: Option<&AncestorHashes>,
     element: &E,
-    context: &mut MatchingContext,
+    context: &mut MatchingContext<E::Impl>,
     flags_setter: &mut F,
 ) -> bool
 where
@@ -318,7 +332,7 @@ pub enum CompoundSelectorMatchingResult {
 pub fn matches_compound_selector<E>(
     selector: &Selector<E::Impl>,
     mut from_offset: usize,
-    context: &mut MatchingContext,
+    context: &mut MatchingContext<E::Impl>,
     element: &E,
 ) -> CompoundSelectorMatchingResult
 where
@@ -361,7 +375,7 @@ where
 pub fn matches_complex_selector<E, F>(
     mut iter: SelectorIter<E::Impl>,
     element: &E,
-    context: &mut MatchingContext,
+    context: &mut MatchingContext<E::Impl>,
     flags_setter: &mut F,
 ) -> bool
 where
@@ -410,7 +424,7 @@ where
 #[inline]
 fn matches_hover_and_active_quirk<Impl: SelectorImpl>(
     selector_iter: &SelectorIter<Impl>,
-    context: &MatchingContext,
+    context: &MatchingContext<Impl>,
     rightmost: Rightmost,
 ) -> bool {
     if context.quirks_mode() != QuirksMode::Quirks {
@@ -465,7 +479,7 @@ enum Rightmost {
 fn matches_complex_selector_internal<E, F>(
     mut selector_iter: SelectorIter<E::Impl>,
     element: &E,
-    context: &mut MatchingContext,
+    context: &mut MatchingContext<E::Impl>,
     relevant_link: &mut RelevantLinkStatus,
     flags_setter: &mut F,
     rightmost: Rightmost,
@@ -589,7 +603,7 @@ where
 fn matches_simple_selector<E, F>(
     selector: &Component<E::Impl>,
     element: &E,
-    context: &mut LocalMatchingContext,
+    context: &mut LocalMatchingContext<E::Impl>,
     relevant_link: &RelevantLinkStatus,
     flags_setter: &mut F,
 ) -> bool
@@ -761,7 +775,7 @@ fn select_name<'a, T>(is_html: bool, local_name: &'a T, local_name_lower: &'a T)
 #[inline]
 fn matches_generic_nth_child<E, F>(
     element: &E,
-    context: &mut LocalMatchingContext,
+    context: &mut LocalMatchingContext<E::Impl>,
     a: i32,
     b: i32,
     is_of_type: bool,
diff --git a/components/selectors/tree.rs b/components/selectors/tree.rs
index d99804c8675..ef353086032 100644
--- a/components/selectors/tree.rs
+++ b/components/selectors/tree.rs
@@ -67,17 +67,18 @@ pub trait Element: Sized + Clone + Debug {
     fn match_non_ts_pseudo_class<F>(
         &self,
         pc: &<Self::Impl as SelectorImpl>::NonTSPseudoClass,
-        context: &mut MatchingContext,
+        context: &mut MatchingContext<Self::Impl>,
         relevant_link: &RelevantLinkStatus,
         flags_setter: &mut F,
     ) -> bool
     where
         F: FnMut(&Self, ElementSelectorFlags);
 
-    fn match_pseudo_element(&self,
-                            pe: &<Self::Impl as SelectorImpl>::PseudoElement,
-                            context: &mut MatchingContext)
-                            -> bool;
+    fn match_pseudo_element(
+        &self,
+        pe: &<Self::Impl as SelectorImpl>::PseudoElement,
+        context: &mut MatchingContext<Self::Impl>,
+    ) -> bool;
 
     /// Whether this element is a `link`.
     fn is_link(&self) -> bool;
diff --git a/components/style/gecko/wrapper.rs b/components/style/gecko/wrapper.rs
index 908af2b6bd3..852436d3d06 100644
--- a/components/style/gecko/wrapper.rs
+++ b/components/style/gecko/wrapper.rs
@@ -1834,7 +1834,7 @@ impl<'le> ::selectors::Element for GeckoElement<'le> {
     fn match_non_ts_pseudo_class<F>(
         &self,
         pseudo_class: &NonTSPseudoClass,
-        context: &mut MatchingContext,
+        context: &mut MatchingContext<Self::Impl>,
         relevant_link: &RelevantLinkStatus,
         flags_setter: &mut F,
     ) -> bool
@@ -1975,7 +1975,7 @@ impl<'le> ::selectors::Element for GeckoElement<'le> {
     fn match_pseudo_element(
         &self,
         pseudo_element: &PseudoElement,
-        _context: &mut MatchingContext
+        _context: &mut MatchingContext<Self::Impl>,
     ) -> bool {
         // TODO(emilio): I believe we could assert we are a pseudo-element and
         // match the proper pseudo-element, given how we rulehash the stuff
diff --git a/components/style/invalidation/element/element_wrapper.rs b/components/style/invalidation/element/element_wrapper.rs
index 294f878cd20..5cedff38fa3 100644
--- a/components/style/invalidation/element/element_wrapper.rs
+++ b/components/style/invalidation/element/element_wrapper.rs
@@ -152,7 +152,7 @@ impl<'a, E> Element for ElementWrapper<'a, E>
     fn match_non_ts_pseudo_class<F>(
         &self,
         pseudo_class: &NonTSPseudoClass,
-        context: &mut MatchingContext,
+        context: &mut MatchingContext<Self::Impl>,
         relevant_link: &RelevantLinkStatus,
         _setter: &mut F,
     ) -> bool
@@ -258,7 +258,7 @@ impl<'a, E> Element for ElementWrapper<'a, E>
     fn match_pseudo_element(
         &self,
         pseudo_element: &PseudoElement,
-        context: &mut MatchingContext,
+        context: &mut MatchingContext<Self::Impl>,
     ) -> bool {
         self.element.match_pseudo_element(pseudo_element, context)
     }
diff --git a/components/style/selector_map.rs b/components/style/selector_map.rs
index 4d1ec302f15..da9180b9549 100644
--- a/components/style/selector_map.rs
+++ b/components/style/selector_map.rs
@@ -162,17 +162,20 @@ impl SelectorMap<Rule> {
     ///
     /// Extract matching rules as per element's ID, classes, tag name, etc..
     /// Sort the Rules at the end to maintain cascading order.
-    pub fn get_all_matching_rules<E, V, F>(&self,
-                                           element: &E,
-                                           rule_hash_target: &E,
-                                           matching_rules_list: &mut V,
-                                           context: &mut MatchingContext,
-                                           quirks_mode: QuirksMode,
-                                           flags_setter: &mut F,
-                                           cascade_level: CascadeLevel)
-        where E: TElement,
-              V: VecLike<ApplicableDeclarationBlock>,
-              F: FnMut(&E, ElementSelectorFlags),
+    pub fn get_all_matching_rules<E, V, F>(
+        &self,
+        element: &E,
+        rule_hash_target: &E,
+        matching_rules_list: &mut V,
+        context: &mut MatchingContext<E::Impl>,
+        quirks_mode: QuirksMode,
+        flags_setter: &mut F,
+        cascade_level: CascadeLevel,
+    )
+    where
+        E: TElement,
+        V: VecLike<ApplicableDeclarationBlock>,
+        F: FnMut(&E, ElementSelectorFlags),
     {
         if self.is_empty() {
             return
@@ -223,15 +226,18 @@ impl SelectorMap<Rule> {
     }
 
     /// Adds rules in `rules` that match `element` to the `matching_rules` list.
-    fn get_matching_rules<E, V, F>(element: &E,
-                                   rules: &[Rule],
-                                   matching_rules: &mut V,
-                                   context: &mut MatchingContext,
-                                   flags_setter: &mut F,
-                                   cascade_level: CascadeLevel)
-        where E: TElement,
-              V: VecLike<ApplicableDeclarationBlock>,
-              F: FnMut(&E, ElementSelectorFlags),
+    fn get_matching_rules<E, V, F>(
+        element: &E,
+        rules: &[Rule],
+        matching_rules: &mut V,
+        context: &mut MatchingContext<E::Impl>,
+        flags_setter: &mut F,
+        cascade_level: CascadeLevel,
+    )
+    where
+        E: TElement,
+        V: VecLike<ApplicableDeclarationBlock>,
+        F: FnMut(&E, ElementSelectorFlags),
     {
         for rule in rules {
             if matches_selector(&rule.selector,
diff --git a/components/style/stylist.rs b/components/style/stylist.rs
index 72445369d7c..2657e1dffdb 100644
--- a/components/style/stylist.rs
+++ b/components/style/stylist.rs
@@ -1198,7 +1198,7 @@ impl Stylist {
         animation_rules: AnimationRules,
         rule_inclusion: RuleInclusion,
         applicable_declarations: &mut V,
-        context: &mut MatchingContext,
+        context: &mut MatchingContext<E::Impl>,
         flags_setter: &mut F,
     )
     where