--- a/servo/components/style/driver.rs
+++ b/servo/components/style/driver.rs
@@ -160,20 +160,19 @@ pub fn traverse_dom<E, D>(
             nodes_remaining_at_current_depth = discovered.len();
         }
     }
 
     // Collect statistics from thread-locals if requested.
     if dump_stats || report_stats {
         let mut aggregate = mem::replace(&mut context.thread_local.statistics, Default::default());
         let parallel = maybe_tls.is_some();
-        if let Some(ref mut tls) = maybe_tls {
-            let slots = unsafe { tls.unsafe_get() };
-            for slot in slots {
-                if let Some(ref cx) = *slot.borrow() {
+        if let Some(tls) = maybe_tls {
+            for mut slot in tls.into_slots().into_vec() {
+                if let Some(cx) = slot.get_mut() {
                     aggregate += cx.statistics.clone();
                 }
             }
         }
 
         if report_stats {
             report_statistics(&aggregate);
         }

--- a/servo/components/style/scoped_tls.rs
+++ b/servo/components/style/scoped_tls.rs
@@ -66,14 +66,13 @@ impl<'scope, T: Send> ScopedTLS<'scope, 
         let mut opt = self.borrow_mut();
         if opt.is_none() {
             f(opt.deref_mut());
         }
 
         RefMut::map(opt, |x| x.as_mut().unwrap())
     }
 
-    /// Unsafe access to the slots. This can be used to access the TLS when
-    /// the caller knows that the pool does not have access to the TLS.
-    pub unsafe fn unsafe_get(&self) -> &[RefCell<Option<T>>] {
-        &self.slots
+    /// Returns the slots, consuming the scope.
+    pub fn into_slots(self) -> Box<[RefCell<Option<T>>]> {
+        self.slots
     }
 }