Fix up script and layout.

components/layout/lib.rs

@@ -93,3 +93,15 @@ pub mod wrapper;
 // For unit tests:
 pub use fragment::Fragment;
 pub use fragment::SpecificFragmentInfo;
+
+/// Returns whether the two arguments point to the same value.
+///
+/// FIXME: Remove this and use Arc::ptr_eq once we require Rust 1.17
+#[inline]
+pub fn arc_ptr_eq<T: 'static>(a: &::std::sync::Arc<T>, b: &::std::sync::Arc<T>) -> bool {
+    ::style::ptr_eq::<T>(&**a, &**b)
+}
+
+// We can't use stylearc for everything in layout, because the Flow stuff uses
+// weak references.
+use style::stylearc::Arc as StyleArc;