diff --git a/components/selectors/context.rs b/components/selectors/context.rs
index e27cd6811bb..6cf516b74fc 100644
--- a/components/selectors/context.rs
+++ b/components/selectors/context.rs
@@ -5,19 +5,6 @@
 use attr::CaseSensitivity;
 use bloom::BloomFilter;
 
-bitflags! {
-    /// Set of flags that determine the different kind of elements affected by
-    /// the selector matching process.
-    ///
-    /// This is used to implement efficient sharing.
-    #[derive(Default)]
-    pub flags StyleRelations: usize {
-        /// Whether this element is affected by presentational hints. This is
-        /// computed externally (that is, in Servo).
-        const AFFECTED_BY_PRESENTATIONAL_HINTS = 1 << 0,
-    }
-}
-
 /// What kind of selector matching mode we should use.
 ///
 /// There are two modes of selector matching. The difference is only noticeable
@@ -87,9 +74,6 @@ impl QuirksMode {
 /// transient data that applies to only a single selector.
 #[derive(Clone)]
 pub struct MatchingContext<'a> {
-    /// Output that records certains relations between elements noticed during
-    /// matching (and also extended after matching).
-    pub relations: StyleRelations,
     /// 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.
@@ -114,7 +98,6 @@ impl<'a> MatchingContext<'a> {
                -> Self
     {
         Self {
-            relations: StyleRelations::empty(),
             matching_mode: matching_mode,
             bloom_filter: bloom_filter,
             visited_handling: VisitedHandlingMode::AllLinksUnvisited,
@@ -132,7 +115,6 @@ impl<'a> MatchingContext<'a> {
                            -> Self
     {
         Self {
-            relations: StyleRelations::empty(),
             matching_mode: matching_mode,
             bloom_filter: bloom_filter,
             visited_handling: visited_handling,
diff --git a/components/selectors/matching.rs b/components/selectors/matching.rs
index 3d6e86671e3..9fc5b0815a1 100644
--- a/components/selectors/matching.rs
+++ b/components/selectors/matching.rs
@@ -714,8 +714,6 @@ fn matches_simple_selector<E, F>(
             matches_last_child(element, flags_setter)
         }
         Component::Root => {
-            // We never share styles with an element with no parent, so no point
-            // in creating a new StyleRelation.
             element.is_root()
         }
         Component::Empty => {
diff --git a/components/style/stylist.rs b/components/style/stylist.rs
index dadcec02a1e..6c429a427bf 100644
--- a/components/style/stylist.rs
+++ b/components/style/stylist.rs
@@ -26,7 +26,7 @@ use selector_parser::{SelectorImpl, PseudoElement};
 use selectors::attr::NamespaceConstraint;
 use selectors::bloom::BloomFilter;
 use selectors::matching::{ElementSelectorFlags, matches_selector, MatchingContext, MatchingMode};
-use selectors::matching::{VisitedHandlingMode, AFFECTED_BY_PRESENTATIONAL_HINTS};
+use selectors::matching::VisitedHandlingMode;
 use selectors::parser::{AncestorHashes, Combinator, Component, Selector, SelectorAndHashes};
 use selectors::parser::{SelectorIter, SelectorMethods};
 use selectors::sink::Push;
@@ -1145,7 +1145,6 @@ impl Stylist {
                                               self.quirks_mode,
                                               flags_setter,
                                               CascadeLevel::UANormal);
-        debug!("UA normal: {:?}", context.relations);
 
         if pseudo_element.is_none() && !only_default_rules {
             // Step 2: Presentational hints.
@@ -1160,12 +1159,7 @@ impl Stylist {
                         assert_eq!(declaration.level(), CascadeLevel::PresHints);
                     }
                 }
-                // Note the existence of presentational attributes so that the
-                // style sharing cache can avoid re-querying them if they don't
-                // exist.
-                context.relations |= AFFECTED_BY_PRESENTATIONAL_HINTS;
             }
-            debug!("preshints: {:?}", context.relations);
         }
 
         // NB: the following condition, although it may look somewhat
@@ -1185,7 +1179,6 @@ impl Stylist {
                                             self.quirks_mode,
                                             flags_setter,
                                             CascadeLevel::UserNormal);
-            debug!("user normal: {:?}", context.relations);
         } else {
             debug!("skipping user rules");
         }
@@ -1194,7 +1187,6 @@ impl Stylist {
         let cut_off_inheritance =
             element.get_declarations_from_xbl_bindings(pseudo_element,
                                                        applicable_declarations);
-        debug!("XBL: {:?}", context.relations);
 
         if rule_hash_target.matches_user_and_author_rules() && !only_default_rules {
             // Gecko skips author normal rules if cutting off inheritance.
@@ -1208,7 +1200,6 @@ impl Stylist {
                                               self.quirks_mode,
                                                   flags_setter,
                                                   CascadeLevel::AuthorNormal);
-                debug!("author normal: {:?}", context.relations);
             } else {
                 debug!("skipping author normal rules due to cut off inheritance");
             }
@@ -1224,7 +1215,6 @@ impl Stylist {
                     ApplicableDeclarationBlock::from_declarations(sa.clone(),
                                                                   CascadeLevel::StyleAttributeNormal));
             }
-            debug!("style attr: {:?}", context.relations);
 
             // Step 5: SMIL override.
             // Declarations from SVG SMIL animation elements.
@@ -1234,7 +1224,6 @@ impl Stylist {
                     ApplicableDeclarationBlock::from_declarations(so.clone(),
                                                                   CascadeLevel::SMILOverride));
             }
-            debug!("SMIL: {:?}", context.relations);
 
             // Step 6: Animations.
             // The animations sheet (CSS animations, script-generated animations,
@@ -1245,7 +1234,6 @@ impl Stylist {
                     ApplicableDeclarationBlock::from_declarations(anim.clone(),
                                                                   CascadeLevel::Animations));
             }
-            debug!("animation: {:?}", context.relations);
         } else {
             debug!("skipping style attr and SMIL & animation rules");
         }
@@ -1264,12 +1252,9 @@ impl Stylist {
                     ApplicableDeclarationBlock::from_declarations(anim.clone(),
                                                                   CascadeLevel::Transitions));
             }
-            debug!("transition: {:?}", context.relations);
         } else {
             debug!("skipping transition rules");
         }
-
-        debug!("push_applicable_declarations: shareable: {:?}", context.relations);
     }
 
     /// Given an id, returns whether there might be any rules for that id in any