time: run full TestTicker test even during short tests

R=golang-dev, r, bradfitz, r
CC=golang-dev
https://golang.org/cl/5689076

src/pkg/time/tick_test.go

@@ -12,9 +12,6 @@ import (
 func TestTicker(t *testing.T) {
 	const Count = 10
 	Delta := 100 * Millisecond
-	if testing.Short() {
-		Delta = 20 * Millisecond
-	}
 	ticker := NewTicker(Delta)
 	t0 := Now()
 	for i := 0; i < Count; i++ {