net: revert Zone in IPNet temporally

Update #4501.

R=golang-dev, r
CC=golang-dev
https://golang.org/cl/7853047

src/pkg/net/interface_bsd.go

@@ -171,7 +171,6 @@ func newAddr(ifi *Interface, m *syscall.InterfaceAddrMessage) (Addr, error) {
 				// the interface index in the interface-local or link-
 				// local address as the kernel-internal form.
 				if ifa.IP.IsLinkLocalUnicast() {
-					ifa.Zone = ifi.Name
 					ifa.IP[2], ifa.IP[3] = 0, 0
 				}
 			}

src/pkg/net/interface_darwin.go

@@ -54,7 +54,6 @@ func newMulticastAddr(ifi *Interface, m *syscall.InterfaceMulticastAddrMessage)
 			// the interface index in the interface-local or link-
 			// local address as the kernel-internal form.
 			if ifma.IP.IsInterfaceLocalMulticast() || ifma.IP.IsLinkLocalMulticast() {
-				ifma.Zone = ifi.Name
 				ifma.IP[2], ifma.IP[3] = 0, 0
 			}
 			ifmat = append(ifmat, ifma.toAddr())

src/pkg/net/interface_freebsd.go

@@ -54,7 +54,6 @@ func newMulticastAddr(ifi *Interface, m *syscall.InterfaceMulticastAddrMessage)
 			// the interface index in the interface-local or link-
 			// local address as the kernel-internal form.
 			if ifma.IP.IsInterfaceLocalMulticast() || ifma.IP.IsLinkLocalMulticast() {
-				ifma.Zone = ifi.Name
 				ifma.IP[2], ifma.IP[3] = 0, 0
 			}
 			ifmat = append(ifmat, ifma.toAddr())

src/pkg/net/interface_linux.go

@@ -156,9 +156,6 @@ func newAddr(ifi *Interface, ifam *syscall.IfAddrmsg, attrs []syscall.NetlinkRou
 			case syscall.AF_INET6:
 				ifa := &IPNet{IP: make(IP, IPv6len), Mask: CIDRMask(int(ifam.Prefixlen), 8*IPv6len)}
 				copy(ifa.IP, a.Value[:])
-				if ifam.Scope == syscall.RT_SCOPE_HOST || ifam.Scope == syscall.RT_SCOPE_LINK {
-					ifa.Zone = ifi.Name
-				}
 				return ifa
 			}
 		}
@@ -229,9 +226,6 @@ func parseProcNetIGMP6(path string, ifi *Interface) []Addr {
 				b[i/2], _ = xtoi2(f[2][i:i+2], 0)
 			}
 			ifma := IPAddr{IP: IP{b[0], b[1], b[2], b[3], b[4], b[5], b[6], b[7], b[8], b[9], b[10], b[11], b[12], b[13], b[14], b[15]}}
-			if ifma.IP.IsInterfaceLocalMulticast() || ifma.IP.IsLinkLocalMulticast() {
-				ifma.Zone = ifi.Name
-			}
 			ifmat = append(ifmat, ifma.toAddr())
 		}
 	}

src/pkg/net/ip.go

@@ -36,7 +36,6 @@ type IPMask []byte
 type IPNet struct {
 	IP   IP     // network number
 	Mask IPMask // network mask
-	Zone string // IPv6 scoped addressing zone
 }
 
 // IPv4 returns the IP address (in 16-byte form) of the