go.net/ipv6: better readability in test

R=golang-codereviews, dave
CC=golang-codereviews
https://golang.org/cl/46740043
diff --git a/ipv6/multicast_test.go b/ipv6/multicast_test.go
index 6801681..cdf597f 100644
--- a/ipv6/multicast_test.go
+++ b/ipv6/multicast_test.go
@@ -75,7 +75,7 @@
 		if err := p.SetControlMessage(cf, toggle); err != nil {
 			t.Fatalf("ipv6.PacketConn.SetControlMessage failed: %v", err)
 		}
-		if err := p.SetDeadline(time.Now().Add(time.Millisecond * 200)); err != nil {
+		if err := p.SetDeadline(time.Now().Add(200 * time.Millisecond)); err != nil {
 			t.Fatalf("ipv6.PacketConn.SetDeadline failed: %v", err)
 		}
 		cm.HopLimit = i + 1
@@ -181,7 +181,7 @@
 		if err := p.SetControlMessage(cf, toggle); err != nil {
 			t.Fatalf("ipv6.PacketConn.SetControlMessage failed: %v", err)
 		}
-		if err := p.SetDeadline(time.Now().Add(time.Millisecond * 200)); err != nil {
+		if err := p.SetDeadline(time.Now().Add(200 * time.Millisecond)); err != nil {
 			t.Fatalf("ipv6.PacketConn.SetDeadline failed: %v", err)
 		}
 		cm.HopLimit = i + 1
diff --git a/ipv6/unicast_test.go b/ipv6/unicast_test.go
index ad42b5e..9542550 100644
--- a/ipv6/unicast_test.go
+++ b/ipv6/unicast_test.go
@@ -53,7 +53,7 @@
 			t.Fatalf("ipv6.PacketConn.SetControlMessage failed: %v", err)
 		}
 		cm.HopLimit = i + 1
-		if err := p.SetWriteDeadline(time.Now().Add(time.Millisecond * 100)); err != nil {
+		if err := p.SetWriteDeadline(time.Now().Add(100 * time.Millisecond)); err != nil {
 			t.Fatalf("ipv6.PacketConn.SetWriteDeadline failed: %v", err)
 		}
 		if n, err := p.WriteTo(wb, &cm, dst); err != nil {
@@ -62,7 +62,7 @@
 			t.Fatalf("ipv6.PacketConn.WriteTo failed: short write: %v", n)
 		}
 		rb := make([]byte, 128)
-		if err := p.SetReadDeadline(time.Now().Add(time.Millisecond * 100)); err != nil {
+		if err := p.SetReadDeadline(time.Now().Add(100 * time.Millisecond)); err != nil {
 			t.Fatalf("ipv6.PacketConn.SetReadDeadline failed: %v", err)
 		}
 		if n, cm, _, err := p.ReadFrom(rb); err != nil {
@@ -146,7 +146,7 @@
 			t.Fatalf("ipv6.PacketConn.SetControlMessage failed: %v", err)
 		}
 		cm.HopLimit = i + 1
-		if err := p.SetWriteDeadline(time.Now().Add(time.Millisecond * 100)); err != nil {
+		if err := p.SetWriteDeadline(time.Now().Add(100 * time.Millisecond)); err != nil {
 			t.Fatalf("ipv6.PacketConn.SetWriteDeadline failed: %v", err)
 		}
 		if n, err := p.WriteTo(wb, &cm, dst); err != nil {
@@ -155,7 +155,7 @@
 			t.Fatalf("ipv6.PacketConn.WriteTo failed: short write: %v", n)
 		}
 		rb := make([]byte, 128)
-		if err := p.SetReadDeadline(time.Now().Add(time.Millisecond * 100)); err != nil {
+		if err := p.SetReadDeadline(time.Now().Add(100 * time.Millisecond)); err != nil {
 			t.Fatalf("ipv6.PacketConn.SetReadDeadline failed: %v", err)
 		}
 		if n, cm, _, err := p.ReadFrom(rb); err != nil {