Fix task-comm-15 type errors and un-xfail.

Author: msullivan

src/test/run-pass/task-comm-15.rs

@@ -1,23 +1,19 @@
-// xfail-stage1
-// xfail-stage2
-// xfail-stage3
-
 use std;
 import std::comm;
 import std::task;
 
-fn start(c : comm::_chan<int>, n: int) {
+fn start(c : comm::chan<int>, n: int) {
     let i: int = n;
 
     while i > 0 { comm::send(c, 0); i = i - 1; }
 }
 
 fn main() {
-    let p = comm::mk_port::<comm::_chan<int>>();
+    let p = comm::mk_port();
     // Spawn a task that sends us back messages. The parent task
     // is likely to terminate before the child completes, so from
     // the child's point of view the receiver may die. We should
     // drop messages on the floor in this case, and not crash!
-    let child = task::_spawn(bind start(p.mk_chan(), 10));
+    let child = task::spawn(bind start(p.mk_chan(), 10));
     let c = p.recv();
 }