Remove empty argument lists from do expressions

src/test/bench/task-perf-alloc-unwind.rs

@@ -17,9 +17,9 @@ fn main() {
 }
 
 fn run(repeat: int, depth: int) {
-    for iter::repeat(repeat as uint) || {
+    for iter::repeat(repeat as uint) {
         #debug("starting %.4f", precise_time_s());
-        do task::try || {
+        do task::try {
             recurse_or_fail(depth, none)
         };
         #debug("stopping %.4f", precise_time_s());