Don't refer to private API in test-repl

test/simple/test-repl.js

@@ -60,7 +60,7 @@ function tcp_test() {
     });
 
     client_tcp.addListener('data', function (data) {
-      read_buffer += data.asciiSlice(0, data.length);
+      read_buffer += data.toString('ascii', 0, data.length);
       common.error("TCP data: " + JSON.stringify(read_buffer) + ", expecting " + JSON.stringify(client_tcp.expect));
       if (read_buffer.indexOf(prompt_tcp) !== -1) {
         assert.strictEqual(client_tcp.expect, read_buffer);
@@ -121,7 +121,7 @@ function unix_test() {
     });
 
     client_unix.addListener('data', function (data) {
-      read_buffer += data.asciiSlice(0, data.length);
+      read_buffer += data.toString('ascii', 0, data.length);
       common.error("Unix data: " + JSON.stringify(read_buffer) + ", expecting " + JSON.stringify(client_unix.expect));
       if (read_buffer.indexOf(prompt_unix) !== -1) {
         assert.strictEqual(client_unix.expect, read_buffer);