Pass a String to spawn_named.

IntoString has been removed from Rust, and named() will take a String, so
there is no good reason to do otherwise here.

components/util/task.rs

@@ -9,7 +9,7 @@ use std::task::TaskBuilder;
 // use rtinstrument;
 use task_state;
 
-pub fn spawn_named<S: IntoCow<'static, String, str>>(name: S, f: proc():Send) {
+pub fn spawn_named(name: String, f: proc():Send) {
     let builder = task::TaskBuilder::new().named(name);
     builder.spawn(proc() {
         // rtinstrument::instrument(f);