1 files changed, 10 insertions, 0 deletions
diff --git a/components/style/values/computed/mod.rs b/components/style/values/computed/mod.rs
index 49b3f2e7285..9864cd67983 100644
--- a/components/style/values/computed/mod.rs
+++ b/components/style/values/computed/mod.rs
@@ -4,6 +4,7 @@
 
 use app_units::Au;
 use euclid::size::Size2D;
+use ordered_float::NotNaN;
 use properties::ComputedValues;
 use std::fmt;
 use super::LocalToCss;
@@ -241,6 +242,15 @@ impl LengthOrPercentage {
             Length(_) | Percentage(_) | Calc(_) => false
         }
     }
+
+    pub fn to_hash_key(&self) -> (Au, NotNaN<f32>) {
+        use self::LengthOrPercentage::*;
+        match *self {
+            Length(l) => (l, NotNaN::new(0.0).unwrap()),
+            Percentage(p) => (Au(0), NotNaN::new(p).unwrap()),
+            Calc(c) => (c.length(), NotNaN::new(c.percentage()).unwrap()),
+        }
+    }
 }
 
 impl fmt::Debug for LengthOrPercentage {