all: revert "all: prefer strings.LastIndexByte over strings.LastIndex"

This reverts https://golang.org/cl/66372.

Updates #22148

Change-Id: I3e94af3dfc11a2883bf28e1d5e1f32f98760b3ee
Reviewed-on: https://go-review.googlesource.com/68431
Reviewed-by: Ian Lance Taylor <iant@golang.org>

handshake_client.go

@@ -848,7 +848,7 @@ func hostnameInSNI(name string) string {
 	if len(host) > 0 && host[0] == '[' && host[len(host)-1] == ']' {
 		host = host[1 : len(host)-1]
 	}
-	if i := strings.LastIndexByte(host, '%'); i > 0 {
+	if i := strings.LastIndex(host, "%"); i > 0 {
 		host = host[:i]
 	}
 	if net.ParseIP(host) != nil {

tls.go

@@ -122,7 +122,7 @@ func DialWithDialer(dialer *net.Dialer, network, addr string, config *Config) (*
 		return nil, err
 	}
 
-	colonPos := strings.LastIndexByte(addr, ':')
+	colonPos := strings.LastIndex(addr, ":")
 	if colonPos == -1 {
 		colonPos = len(addr)
 	}