strings: Replace s[:] to s where s is a slice.

Change-Id: Ie7ba3f9ece9b0fc0e8a5c92fbae9c3b558815e4c
Reviewed-on: https://go-review.googlesource.com/c/141997
Run-TryBot: Iskander Sharipov <iskander.sharipov@intel.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Iskander Sharipov <iskander.sharipov@intel.com>

src/strings/replace.go

@@ -459,7 +459,7 @@ func (r *byteReplacer) WriteString(w io.Writer, s string) (n int, err error) {
 	buf := make([]byte, bufsize)
 
 	for len(s) > 0 {
-		ncopy := copy(buf, s[:])
+		ncopy := copy(buf, s)
 		s = s[ncopy:]
 		for i, b := range buf[:ncopy] {
 			buf[i] = r[b]