net/http: remove dreg of obsoleted network poller

R=golang-dev, r
CC=golang-dev
https://golang.org/cl/13261049

src/pkg/net/http/z_last_test.go

@@ -23,7 +23,6 @@ func interestingGoroutines() (gs []string) {
 		}
 		stack := strings.TrimSpace(sl[1])
 		if stack == "" ||
-			strings.Contains(stack, "created by net.newPollServer") ||
 			strings.Contains(stack, "created by net.startServer") ||
 			strings.Contains(stack, "created by testing.RunTests") ||
 			strings.Contains(stack, "closeWriteAndWait") ||