Fix layout cache on nightly

src/util.rs

@@ -1,12 +0,0 @@
-use std::collections::hash_map::RandomState;
-use std::hash::{Hash, Hasher, BuildHasher};
-
-use layout::Rect;
-
-pub fn hash<T: Hash>(t: &T, area: &Rect) -> u64 {
-    let state = RandomState::new();
-    let mut hasher = state.build_hasher();
-    t.hash(&mut hasher);
-    area.hash(&mut hasher);
-    hasher.finish()
-}