Store slow selector flags in a hashmap.

This reduces the flag setting overhead on a pessimal testcase from over a
second to ~20ms.

1 files changed, 9 insertions, 0 deletions

diff --git a/components/script/layout_wrapper.rs b/components/script/layout_wrapper.rs
index 4b118bdf7f1..e4df1b77ec3 100644
--- a/components/script/layout_wrapper.rs
+++ b/components/script/layout_wrapper.rs
@@ -55,6 +55,7 @@ use servo_atoms::Atom;
 use servo_url::ServoUrl;
 use std::fmt;
 use std::fmt::Debug;
+use std::hash::{Hash, Hasher};
 use std::marker::PhantomData;
 use std::mem::transmute;
 use std::sync::Arc;
@@ -475,6 +476,14 @@ impl<'le> PartialEq for ServoLayoutElement<'le> {
     }
 }
 
+impl<'le> Hash for ServoLayoutElement<'le> {
+    fn hash<H: Hasher>(&self, state: &mut H) {
+        self.element.hash(state);
+    }
+}
+
+impl<'le> Eq for ServoLayoutElement<'le> {}
+
 impl<'le> ServoLayoutElement<'le> {
     fn from_layout_js(el: LayoutJS<Element>) -> ServoLayoutElement<'le> {
         ServoLayoutElement {