libextra: Another round of de-Cell-ing.

34 uses of `Cell` remain.

src/libstd/unstable/mod.rs

@@ -37,15 +37,13 @@ The executing thread has no access to a task pointer and will be using
 a normal large stack.
 */
 pub fn run_in_bare_thread(f: proc()) {
-    use cell::Cell;
     use rt::thread::Thread;
 
-    let f_cell = Cell::new(f);
     let (port, chan) = comm::stream();
     // FIXME #4525: Unfortunate that this creates an extra scheduler but it's
     // necessary since rust_raw_thread_join is blocking
     do task::spawn_sched(task::SingleThreaded) {
-        Thread::start(f_cell.take()).join();
+        Thread::start(f).join();
         chan.send(());
     }
     port.recv();